WO1991008052A1 - Electrical control system for electrostatic precipitator - Google Patents

Electrical control system for electrostatic precipitator Download PDF

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Publication number
WO1991008052A1
WO1991008052A1 PCT/US1989/005430 US8905430W WO9108052A1 WO 1991008052 A1 WO1991008052 A1 WO 1991008052A1 US 8905430 W US8905430 W US 8905430W WO 9108052 A1 WO9108052 A1 WO 9108052A1
Authority
WO
WIPO (PCT)
Prior art keywords
precipitator
form factor
computer
value
varying
Prior art date
Application number
PCT/US1989/005430
Other languages
French (fr)
Inventor
David F. Johnston
Terry L. Farmer
Original Assignee
Bha Group, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bha Group, Inc. filed Critical Bha Group, Inc.
Priority to PCT/US1989/005430 priority Critical patent/WO1991008052A1/en
Priority to EP90911823A priority patent/EP0504143B1/en
Priority to CA002069881A priority patent/CA2069881C/en
Priority to DE69030583T priority patent/DE69030583T2/en
Priority to DK90911823.4T priority patent/DK0504143T3/en
Priority to PCT/US1990/003714 priority patent/WO1991008053A1/en
Publication of WO1991008052A1 publication Critical patent/WO1991008052A1/en

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B03SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03CMAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C3/00Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
    • B03C3/34Constructional details or accessories or operation thereof
    • B03C3/66Applications of electricity supply techniques
    • B03C3/68Control systems therefor

Definitions

  • An electrostatic precipitator is an air pollution control device designed to electrically charge and col- lect particulates generated from industrial processes such as those occurring in cement plants, pulp and paper mills and utilities. Particulate laden gas flows through the precipitator where the particulate is negatively charged. These negatively charged particles are attracted to, and collected by, positively charged metal plates. The cleaned process gas may then be further processed or safely discharged to the atmos- phere.
  • a precipitator should be operated at the highest practical energy level to increase both the particle charge and collection capabilities of the system.
  • "sparking" i.e., a temporary short which creates a conductive gas path
  • This sparking can damage the precipitator and control system.
  • the key to maximizing the efficiency of an electrostatic precipitator is to operate at the highest energy level possible.
  • the electrostatic precipitator should constantly operate at its point of greatest efficiency.
  • the conditions such as temperature, combustion rate, and the chemical composition of the particulate being collected, under which an electrostatic precipitator operates are constantly changing. This complicates the cal ⁇ culation of parameters critical to a precipitator's operation.
  • the current limiting reactor (CLR) which controls and limits the current entering the precipitator and matches the precipitator load to the line to allow for maximum power transfer to the precipitator.
  • the current limiting reactor (CLR) has two main functions. The first is to shape the voltage and current wave forms that appear in the precipitator for maximum collection efficiency. The second function of the CLR is to control and limit current.
  • SCRs Two SCRs are connected in an inverse parallel arrangement in series be- tween the power source and the precipitator high voltage transformer.
  • the power source is an alternating current (AC) sinusoidal wave form whose value is zero at the beginning and end of every half cycle, and is a positive value during one half cycle and a negative value during the next half cycle. For a power source with a 60 Hz. frequen- cy, this would occur every 8.33 milliseconds.
  • Only one SCR conducts at a time on al ⁇ ternate half cycles.
  • the automatic voltage control provides gating such that the appropriate SCR may be switched on at the same point during the half cycle to provide power control.
  • the SCR remains switched on or in conduction until the power source becomes zero at the end of the half cycle. The cycle is then repeated for the next half cycle and the opposite SCR.
  • the SCRs cannot be switched off by the automatic volt ⁇ age control. If the precipitator spark level is reached with no control of current to the precipitator, equipment damage can occur.
  • the CLR provides a means of controlling and limiting the current flow to the precipitator until the conducting SCR switches off at the end of the half cycle. Because of its critical role in maximizing electrostatic precipitator perfor ⁇ mance, it is vital that the CLR be properly sized. In the prior art, the CLR is sized at 30%-50% of the impedance of the transformer/rectifier (T/R) set.
  • this invention strives to improve the fractional conduction "trial and error" method of properly sizing the CLR used in the prior art.
  • a more accurate method of analysis is to measure the root mean square (RMS) value and the average value of the primary current, then divide RMS by average to obtain the form factor.
  • the theoretical form factor in a purely resistive circuit is 1.11. It is well known in the art that at a low form factor of approximately 1.2, maximum power transfer and col ⁇ lection efficiency is achieved. Accordingly, an object of this invention to calculate the form factor to provide a verifiable basis on which to measure electrical efficiency of the CLR and other electrical components. Since a form factor can be calculated using primary voltage as well as primary current values, it is also an object of this invention to give the user the option of using either value.
  • a further object is to reduce start-up time by allowing programmable operat ⁇ ing instructions that can be calculated and down loaded into the automatic voltage control. This will relieve the operator of initially having to calculate values and set the automatic voltage control, CLR, and other electrical components which will save time and reduce operator error.
  • Another important object is to minimize repair and troubleshooting time and expense by providing an automatic voltage control with the ability to diagnose fault conditions and suggest possible corrective measures.
  • Another object of this invention is to reduce repair time and costs by locating often damaged components in an easily accessible location. All over-voltage protec ⁇ tion is positioned in a plug-in board. In the event that the automatic voltage control is damaged by over voltage, or modifications are needed for another application, this board can be removed and repaired without disassembling the entire automatic volt- age control.
  • a further object of this invention is to provide a portable, stand-alone form fac ⁇ tor meter for use separate from an automatic voltage control.
  • This form factor meter will calculate form factor for any electrostatic precipitator or similar equipment and immediately inform the operator how efficiently the equipment is performing.
  • Fig.2 is a block diagram illustrating in greater detail the input scaling and sig ⁇ nal conditioning circuitry schematically shown in Fig. 1;
  • 0 Fig. 3 is a block diagram illustrating in greater detail the components of the computer control schematically shown in Fig. 1; and
  • Fig.4 is a block diagram of the form factor meter of this invention illustrated as a stand-alone test instrument.
  • This invention specifically contemplates determining the form factor of an 5 electrostatic precipitator to accurately measure whether the electrical components are sized properly.
  • a device to measure the form factor is described both as part of an automatic voltage control system and as a stand-alone form factor meter.
  • a power source 10 typically a 480-volt, single phase, AC power source, has two output terminals 12 and 14.
  • Output terminal 12 connects serially to an inverse parallel SCR 1 and SCR 2, to a current limiting reactor 16, and to one side of the primary of a step-up transformer 18.
  • Output terminal 14 connects to the other side of the primary of transformer 18.
  • the secondary of transformer 18 is connected across a full-wave rectifier 20 which supplies power to precipitator 22.
  • Transformer 18 and 5 full-wave rectifier 20, in combination, is commonly referred to as the T/R set.
  • the positive output of rectifier 20 passes through a current meter 34 and resis ⁇ tor 32.
  • the resistor 32 connects with an input scaling and signal conditioner 28.
  • the negative output of rectifier 20 connects both to precipitator 22 as well as through a resistor 36 and a resistor 38 to ground.
  • the voltage across resistor 38 is sensed by a 30 voltage meter 39 and voltage meter 39 connects with input scaling and signal con ⁇ ditioner 28.
  • a current transformer 26 senses the input current and sends a signal to input scaling and signal conditioner 28.
  • the primary of a potential transformer 30 is con ⁇ nected across the power input before transformer 18 and the secondary of transformer 35 30 is connected to the input scaling and signal conditioner 28.
  • the output of input scaling and signal conditioner 28 is connected to a com ⁇ puter 40 which is connected to an SCR control circuit 24.
  • Computer 40 is also con ⁇ nected to a display 42 and bi-directionally connected to an input/output port 44.
  • Display 42 may typically comprise an LM4457BG4C40LNY chip such as manufac- tured by Densitron.
  • Input scaling and signal conditioner 28 is shown in detail in Fig.2.
  • Primary cur ⁇ rent is received from current transformer 26 and flows to two separate circuits, an averaging circuit 46 and an RMS circuit 48.
  • the averaging circuit 46 has two opera ⁇ tional amplifiers 50 and 51 and two diodes 52 and 53.
  • the operational amplifiers 50 and 51 may typically comprise TL032CP chips as manufactured by Texas Instruments of Dallas, Texas; and diodes 52 and 53 may typically comprise IN4148 chips as also manufactured by Texas Instruments of Dallas, Texas.
  • the output of averaging circuit 46 connects with computer 40.
  • the RMS circuit 48 has an operational amplifier 54, typically the above mentioned TL032CP chip, and an RMS converter 56, typically an AD536AJD chip as manufactured by Analog Devices of Norwood, Massachusetts.
  • the output of RMS circuit 48 connects with computer 40.
  • RMS circuit 58 Primary voltage is received from transformer 30 and flows to an RMS circuit 58.
  • RMS circuit 58 is identical to RMS circuit 48 except that RMS circuit 58 receives primary voltage.
  • the output of RMS circuit 58 connects with computer 40.
  • the values of a resistor 60 and a resistor 62 control whether the averaging circuit 46 receives primary voltage or primary current.
  • Secondary voltage is received from voltage meter 39 and passes through two operational amplifiers 64 and 65 (both typically TL032CP chips as manufactured by Texas Instruments of Dallas, Texas) and enters computer 40. Secondary current is received from current meter 34 and connects to computer 40.
  • Computer 40 is detailed in Fig. 3.
  • a multiplexer 66 of computer 40 receives data from input scaling and signal conditioner 28. Multiplexer 66 may typically com ⁇ prise an ADG508AKN chip such as manufactured by Analog Devices of Norwood, Massachusetts. Multiplexer 66 is connected directly to a logic means 72 and connected in series with a buffer 68, an A/D converter 70 and logic means 72.
  • the buffer 68 may typically be a Texas Instruments TL032CP operational amplifier chip and the A/D converter 70 may typically comprise an AD573JN chip such as manufactured by Analog Devices of Norwood, Massachusetts.
  • Logic means 72 is connected to SCR control circuit 24 and display 42, and is bi-directionally connected to input/output port 44 and bi- directionally connected to a memory means 74.
  • Fig. 4 is a block diagram of a form factor meter as would be used as a stand ⁇ alone device.
  • An external sensor 76 is connected to the input scaling and signal con- ditioner 28 which connects with computer 40, and computer 40 connects to display 42.
  • a power source 78 will power input scaling and signal conditioner 28, computer 40 and display 42.
  • Power source 78 may consist of circuitry allowing the form factor meter to plug into an external power source, or a battery or similar power supply.
  • Sensor 76 may typically be a clamp as found on many models of current meters.
  • the primary embodiment of this invention is to work in coopera ⁇ tion with an electrostatic precipitator automatic voltage control device.
  • a repre ⁇ sentative example of an electrostatic precipitator automatic voltage control is shown in my earlier patent U.S. Patent No. 4,605,424, issued August 12, 1986 and entitled 0 "Method and Apparatus for Controlling Power to an Electronic Precipitator", which is incorporated by reference herein. It should be recognized that, while these two in ⁇ ventions may share hardware, the problems addressed by each are distinct.
  • the '424 patent controls voltage or power to the precipitator while this invention addresses the inefficiency of improperly sized components of an electrostatic precipitator. 5
  • input/output port 44 is utilized to communicate information to logic means 72 within computer 40.
  • Communication may be accomplished through a built-in keyboard, portable lap-top computer, remote computer connected to the input/output port 44 directly or by modem, or by a similar means.
  • Equipment size and power levels are communicated which allows initial calculations by logic means 72 to 0 determine the proper setting of CLR 16 and other settings for other equipment.
  • CLR 16 and other equipment may be set automatically, or the appropriate values may be sent to display 42 and the equipment set manually — according to the previously cal ⁇ culated settings.
  • the desired spark rate, SCR firing angle, fault conditions and all other information required by the automatic volt- 5 age control to supply power to the precipitator is communicated through input/out ⁇ put port 44 to logic means 72. This relieves the operator from having to manually set the equipment and helps to eliminate operator error. Information and calculated values required for future reference are sent from logic means 72 to memory 74.
  • the desired power level is sent from logic means 72, within computer 40, to 0 SCR control circuit 24 where the power level is converted into an SCR firing angle.
  • Power is applied to precipitator 22 in terms of SCR firing angle degrees.
  • the sinusoidal electrical cycle consists of 360 degrees, and consists of a positive half cycle and a negative half cycle with respect to polarity.
  • Each SCR can be fired anywhere from 0 degrees to 180 degrees in the electrical cycle, 0 degrees being full power and 35 180 degrees being 0 power.
  • an SCR is fired at 45 degrees, for example, it will conduct from 45 degrees to 180 degrees. Therefore, a difference in firing angles can be represented as a distance along the abscissa of the sine wave. Due to polarity rever ⁇ sal, the SCR stops conducting at 180 degrees.
  • SCR 1 and SCR 2 The normal operating state of SCR 1 and SCR 2 is 180 degrees which allows 0 power from power source 10 to pass through to precipitator 22. After SCR firing cir- cuit 24 translates the voltage level into the appropriate angle, this angle is sent to SCR 1 and SCR 2 which begins allowing the appropriate power to pass from power source 10 down line to step-up transformer 18 and full-wave rectifier 20, and eventually to precipitator 22.
  • a primary object of CLR 16 is to filter and shape the signal leaving SCR 1 and SCR 2.
  • the shape of the secondary current filtered wave will be a broad, low wave form since the average value produces work and the peak value produces sparking.
  • the peak and average values of the signal entering precipitator 22 will be very close.
  • Precipitator 22 acts as a capacitor and CLR 16 acts as an in ⁇ ductor, therefore, if inductive CLR 16 is matched with capacitive precipitator load 22, the result will be a purely resistive load and maximum efficiency will occur. This is at- tained by measuring the form factor and sizing the equipment within the circuit to at ⁇ tain a form factor approaching 1.11.
  • Full-wave rectifier 20 converts the AC signal which passes through SCR 1 and SCR 2 into a pulsating DC signal.
  • the positive output of full-wave rectifier 20 passes through current meter 34 and resistor 32 to ground.
  • the negative output of full-wave rectifier 20 connects directly to precipitator 22 as well as through voltage dividing resis- tors 36 and 38 to ground.
  • Voltage meter 39 is in series with metering resistor 36. Cur ⁇ rent meter 34 and voltage meter 39 are utilized to sense when sparking occurs in precipitator 22 and to sense fault conditions.
  • the data obtained from voltage meter 39 and current meter 34 are sent to input scaling and signal conditioner 28 and even ⁇ tually to computer 40.
  • Current transformer 26 measures the primary current and transformer 30 provides the primary voltage with respect to transformer 18. These values are sent to input scaling and signal conditioner 28 where they are converted to a state which al ⁇ lows the form factor to be calculated.
  • Fig. 2 The circuitry that is principal to this invention can be found in Fig. 2. Primary current and voltage along with secondary current and voltage each enter input scaling and signal conditioner 28. Primary current from current transformer 26 is introduced and flows to averaging circuit 46 and RMS circuit 48.
  • the first half of averaging circuit 46 is a precision rectifier consisting of an operational amplifier 50 and two diodes 52 and 53. This precision rectifier provides a DC output that is not offset by the voltage drop of the diodes.
  • a second operation ⁇ al amplifier 51 provides an averaging circuit such that the input of the total circuit 46 is AC and the output of the total circuit 46 is DC, proportional to the average value of the AC wave.
  • the output of averaging circuit 46 is routed to computer 40.
  • the primary current also enters an RMS circuit 48.
  • Operational amplifier 54 provides an input buffer and signal conditioning while RMS converter 56 changes the AC input to its RMS value and this value is routed to computer 40.
  • Computer 40 now has primary current in two forms: average and RMS.
  • Transformer 30 provides primary voltage to input scaling and signal con ⁇ ditioner 28.
  • the primary voltage enters RMS circuit 58 which changes the AC input to its RMS value, in the same manner as RMS circuit 48, and this value is routed to computer 40.
  • resistor 60 and 62 are provided.
  • the input scaling and signal conditioner 28 is configured to read the true RMS value and average value of the primary current for measuring form factor.
  • the true RMS value and average value of the primary voltage can be used to calculate form factor.
  • Resistors 60 and 62 allow the option of calculating either the average of the primary current or the average of the primary voltage so that the form factor can be calculated using either current or volt ⁇ age.
  • Secondary current and voltage signals from circuitry associated with current meter 34 and voltage meter 39 both enter input scaling and signal conditioner 28.
  • Secondary voltage passes through operational amplifiers 64 and 65 which provides isolation and scaling before it is routed to computer 40.
  • the secondary current signal from resistor 32 is also routed to computer 40.
  • Multiplexer 66 accepts each of the output signals of input scaling and signal conditioner 28. Upon a signal from logic means 72, multiplexer 66 allows one of the input signals from input scaling and signal conditioner 28 to pass. This signal passes through buffer 68, is converted to a digital signal at the A/D converter 70 and enters logic means 72.
  • logic means 72 receives both an RMS value and an average value for either primary current or primary voltage, the RMS value is divided by the average value to obtain the form factor. The form factor value is then transmitted to display 42.
  • Display 42 can be a liquid crystal display or similar digital display, a CRT displaying the value graphically, a printed numerical or graphical representation or similar display. It is also understood that the form factor value can be transmitted to input/output port 44 and obtained remotely. An operator evaluates whether this form factor value is sufficiently close to the
  • All four inputs to multiplexer 66 are retrieved and analyzed by logic means 72 rapidly and continuously.
  • logic means 72 determines that current meter 34 ex ⁇ perienced a sudden increase in current, a spark condition in precipitator 22 is analyzed.
  • logic means 72 transmits information to SCR control circuit 24 to not energize again until the spark is extinguished. Since SCRs cannot shut off until a voltage level of 0 is received by them, up to an 8.33 mil- lisecond delay, CLR 16 limits the current to precipitator 22 until the SCRs actually stop conducting.
  • the time delay before re-energizing and the procedure for deter ⁇ mining the appropriate firing angle with which to start energizing the SCRs is part of the automatic voltage control logic sequence and is detailed in the '424 patent.
  • the '424 patent also details how fault conditions are recognized and power shut down attained. But, in the '424 patent, determining what type of fault, the cause, specific location of the fault and potential solutions is left to the operator.
  • the present invention incorporates diagnostic capabilities which greatly reduce down time. Therefore, computer 40 is fitted with non-volative memory 74, a device capable of retaining information when the power is removed.
  • non-volative memory 74 a device capable of retaining information when the power is removed.
  • the memory device containing its pre-programmed information informs the computer 40 of a short condition.
  • Computer 40 analyzes the condition, retrieves the proper wording for a short and the corrective measures pre-programmed into memory 74, and routes them to display 42.
  • a major problem with the prior art has been that automatic voltage controls are connected to a precipitator that operates on a number of voltages.
  • the line volt- age is normally from 380-575 volts, 50-60 Hz.
  • the secondary voltage is roughly 50,000 volts.
  • the automatic voltage control runs on five (5) volts.
  • the electrical supply is 120 volts.
  • a shorted primary to secondary transformer 18 can deliver damag ⁇ ing voltages. Therefore, a means must be available of protecting the automatic volt- age control that can be easily and quickly repaired.
  • This invention provides the automatic voltage control with a plug-in input circuit board where all the scaling and over-voltage protection is contained. When the automatic voltage control is wired into the system, it does not have to be removed to be repaired. This results in sig ⁇ nificant time and cost reductions.
  • the above mentioned form factor measurement can be a part of the automatic voltage control that controls the SCRs or can be developed as a separate testing device to measure the efficiency and proper sizing of electrostatic precipitator components.
  • Fig. 4 shows a form factor meter as a stand-alone device.
  • This device consists of sen ⁇ sor 76 which can typically be a clamp found on many present current transformers.
  • Sensor 76 will sense the primary current of an electrostatic precipitator or similar device and provide this as an input to input scaling and signal conditioner 28.
  • Input scaling and signal conditioner 28 will convert this current measurement to the average current and true RMS values.
  • the true RMS value and average current value will be sent to computer 40 where the form factor calculations will be performed. Once the form factor is determined, this value will be transmitted to display 42 for the operator to read and analyze the efficiency of the equipment being measured.
  • Power source 78 will be available to drive each of these components. As a stand-alone, portable device, this form factor meter will be valuable to quickly and safely determine the present operating efficiency of electrostatic precipitators and similar equipment.

Abstract

Form factor measurement and fault detection equipment to determine proper sizing of electrical components and efficiency of an electrostatic precipitator (22) by calculating a system form factor from either primary voltage or current. A power source (10) connects serially to an inverse parallel SCR1 and SCR2, to a current limiting reactor (16), and to a T/R set comprising a transformer (18) and rectifier (20) which supply power to precipitator (22). A current transformer (26) senses input current between the reactor (16) and T/R set (18, 20) to signal an input scaling and signal conditioner (28) connected to a current meter (34), a voltage meter (39) and a computer (40) having a display monitor (42). The computer (40) is also connected to an SCR control circuit (24) of SCR1 and SCR2. The appropriate electrical characteristic is converted to both its RMS value and average value and then sent to the computer (40). The computer (40) divides the RMS value by the average value and sends the resulting form factor value to the display (42). If system form factor value is not sufficiently close to the purely resistive circuit value of 1.11, then equipment resizing is needed to increase system efficiency.

Description

ELECTRICAL CONTROL SYSTEM FOR ELECTROSTATIC PRECIPITATOR
Background and Summary of the Invention This invention relates generally to electrostatic precipitators for air pollution control and, more specifically, concerns the electrical control of electrostatic precipitators. Continuous emphasis on environmental quality has resulted in increasingly strenuous regulatory controls on industrial emissions. One technique which has proven highly effective in controlling air pollution has been the removal of undesirable paniculate matter from a gas stream by electrostatic precipitation. An electrostatic precipitator is an air pollution control device designed to electrically charge and col- lect particulates generated from industrial processes such as those occurring in cement plants, pulp and paper mills and utilities. Particulate laden gas flows through the precipitator where the particulate is negatively charged. These negatively charged particles are attracted to, and collected by, positively charged metal plates. The cleaned process gas may then be further processed or safely discharged to the atmos- phere.
To maximize the particulate collection, a precipitator should be operated at the highest practical energy level to increase both the particle charge and collection capabilities of the system. Concurrently, there is a level above which "sparking" (i.e., a temporary short which creates a conductive gas path) occurs in the system. Left un- controlled, this sparking can damage the precipitator and control system. The key to maximizing the efficiency of an electrostatic precipitator is to operate at the highest energy level possible.
Ideally, the electrostatic precipitator should constantly operate at its point of greatest efficiency. Unfortunately, the conditions , such as temperature, combustion rate, and the chemical composition of the particulate being collected, under which an electrostatic precipitator operates are constantly changing. This complicates the cal¬ culation of parameters critical to a precipitator's operation. This is particularly true of the current limiting reactor (CLR) which controls and limits the current entering the precipitator and matches the precipitator load to the line to allow for maximum power transfer to the precipitator. The current limiting reactor (CLR) has two main functions. The first is to shape the voltage and current wave forms that appear in the precipitator for maximum collection efficiency. The second function of the CLR is to control and limit current.
Power control in a precipitator is achieved by silicon controlled rectifiers
(SCRs). Two SCRs are connected in an inverse parallel arrangement in series be- tween the power source and the precipitator high voltage transformer. The power source is an alternating current (AC) sinusoidal wave form whose value is zero at the beginning and end of every half cycle, and is a positive value during one half cycle and a negative value during the next half cycle. For a power source with a 60 Hz. frequen- cy, this would occur every 8.33 milliseconds. Only one SCR conducts at a time on al¬ ternate half cycles. The automatic voltage control provides gating such that the appropriate SCR may be switched on at the same point during the half cycle to provide power control. The SCR remains switched on or in conduction until the power source becomes zero at the end of the half cycle. The cycle is then repeated for the next half cycle and the opposite SCR. The SCRs cannot be switched off by the automatic volt¬ age control. If the precipitator spark level is reached with no control of current to the precipitator, equipment damage can occur. The CLR provides a means of controlling and limiting the current flow to the precipitator until the conducting SCR switches off at the end of the half cycle. Because of its critical role in maximizing electrostatic precipitator perfor¬ mance, it is vital that the CLR be properly sized. In the prior art, the CLR is sized at 30%-50% of the impedance of the transformer/rectifier (T/R) set. This calculation results in a rough estimate of the appropriate CLR size for a given application. The actual electrical efficiency is subjectively measured by viewing the shape and duration of the wave form of the secondary current with an oscilloscope and estimating the frac¬ tional conduction. The CLR is then adjusted by trial and error in an attempt to ob¬ tain the desired collection efficiency. Fractional conduction and other methods used to size CLRs in the prior art have been crude and inaccurate, allowing for operation¬ al inefficiency and equipment damage including blown fuses, equipment failure and inefficient performance from other components of the system. The production output of many industries may be limited by the amount of pol¬ lution discharged. The government sets limits on the amount of pollution a facility may generate and discharge. In the event this limit is exceeded, a facility is subject to fines and temporary or permanent shut-down. Therefore, in terms of profitability, it is imperative that the electrostatic precipitator operate at its highest efficiency, and in the event of a malfunction, minimizing down time is a high priority.
The prior art requires time consuming calculations to determine initial opera¬ tion settings for precipitator controls. In the event of a malfunction or fault, deter¬ mining the exact problem and repairing or replacing the faulty component is time consuming and often requires disassembling of much of the precipitator or its con- trols. These limitations of the prior art all lead to operation inefficiency, equipment damage, inadequate performance and increased pollution emissions. Summary of the Invention Along felt need in the air pollution control industry remains for improvements in the electrical control of electrostatic precipitators to alleviate the many operation¬ al and performance difficulties which have been encountered in the past. The primary goal of this invention is to fulfill this need.
Given the critical role the CLR plays in maximizing electrostatic precipitator performance, this invention strives to improve the fractional conduction "trial and error" method of properly sizing the CLR used in the prior art. A more accurate method of analysis is to measure the root mean square (RMS) value and the average value of the primary current, then divide RMS by average to obtain the form factor. The theoretical form factor in a purely resistive circuit is 1.11. It is well known in the art that at a low form factor of approximately 1.2, maximum power transfer and col¬ lection efficiency is achieved. Accordingly, an object of this invention to calculate the form factor to provide a verifiable basis on which to measure electrical efficiency of the CLR and other electrical components. Since a form factor can be calculated using primary voltage as well as primary current values, it is also an object of this invention to give the user the option of using either value.
A further object is to reduce start-up time by allowing programmable operat¬ ing instructions that can be calculated and down loaded into the automatic voltage control. This will relieve the operator of initially having to calculate values and set the automatic voltage control, CLR, and other electrical components which will save time and reduce operator error.
Another important object is to minimize repair and troubleshooting time and expense by providing an automatic voltage control with the ability to diagnose fault conditions and suggest possible corrective measures. Another object of this invention is to reduce repair time and costs by locating often damaged components in an easily accessible location. All over-voltage protec¬ tion is positioned in a plug-in board. In the event that the automatic voltage control is damaged by over voltage, or modifications are needed for another application, this board can be removed and repaired without disassembling the entire automatic volt- age control.
A further object of this invention is to provide a portable, stand-alone form fac¬ tor meter for use separate from an automatic voltage control. This form factor meter will calculate form factor for any electrostatic precipitator or similar equipment and immediately inform the operator how efficiently the equipment is performing. Other and further objects of the invention, together with the features of novel¬ ty appurtenant thereto, will appear in the course of the following description. Description of the Drawings In the accompanying drawings which form a part of the specification and are to be read in conjunction therewith, and in which like reference numerals are used to indicate like parts in the various views: Fig. 1 is a block diagram of an electrical sizing circuit constructed in accord¬ ance with a preferred embodiment of the invention for an automatic voltage control circuitry;
Fig.2 is a block diagram illustrating in greater detail the input scaling and sig¬ nal conditioning circuitry schematically shown in Fig. 1; 0 Fig. 3 is a block diagram illustrating in greater detail the components of the computer control schematically shown in Fig. 1; and
Fig.4 is a block diagram of the form factor meter of this invention illustrated as a stand-alone test instrument.
This invention specifically contemplates determining the form factor of an 5 electrostatic precipitator to accurately measure whether the electrical components are sized properly. A device to measure the form factor is described both as part of an automatic voltage control system and as a stand-alone form factor meter.
Utilizing the form factor to properly size electrical components as part of an electrostatic precipitator's automatic voltage control is shown generally in Fig. 1 of 0 the drawings. A power source 10, typically a 480-volt, single phase, AC power source, has two output terminals 12 and 14. Output terminal 12 connects serially to an inverse parallel SCR 1 and SCR 2, to a current limiting reactor 16, and to one side of the primary of a step-up transformer 18. Output terminal 14 connects to the other side of the primary of transformer 18. The secondary of transformer 18 is connected across a full-wave rectifier 20 which supplies power to precipitator 22. Transformer 18 and 5 full-wave rectifier 20, in combination, is commonly referred to as the T/R set.
The positive output of rectifier 20 passes through a current meter 34 and resis¬ tor 32. The resistor 32 connects with an input scaling and signal conditioner 28. The negative output of rectifier 20 connects both to precipitator 22 as well as through a resistor 36 and a resistor 38 to ground. The voltage across resistor 38 is sensed by a 30 voltage meter 39 and voltage meter 39 connects with input scaling and signal con¬ ditioner 28.
A current transformer 26 senses the input current and sends a signal to input scaling and signal conditioner 28. The primary of a potential transformer 30 is con¬ nected across the power input before transformer 18 and the secondary of transformer 35 30 is connected to the input scaling and signal conditioner 28. The output of input scaling and signal conditioner 28 is connected to a com¬ puter 40 which is connected to an SCR control circuit 24. Computer 40 is also con¬ nected to a display 42 and bi-directionally connected to an input/output port 44. Display 42 may typically comprise an LM4457BG4C40LNY chip such as manufac- tured by Densitron.
Input scaling and signal conditioner 28 is shown in detail in Fig.2. Primary cur¬ rent is received from current transformer 26 and flows to two separate circuits, an averaging circuit 46 and an RMS circuit 48. The averaging circuit 46 has two opera¬ tional amplifiers 50 and 51 and two diodes 52 and 53. The operational amplifiers 50 and 51 may typically comprise TL032CP chips as manufactured by Texas Instruments of Dallas, Texas; and diodes 52 and 53 may typically comprise IN4148 chips as also manufactured by Texas Instruments of Dallas, Texas. The output of averaging circuit 46 connects with computer 40. The RMS circuit 48 has an operational amplifier 54, typically the above mentioned TL032CP chip, and an RMS converter 56, typically an AD536AJD chip as manufactured by Analog Devices of Norwood, Massachusetts. The output of RMS circuit 48 connects with computer 40.
Primary voltage is received from transformer 30 and flows to an RMS circuit 58. RMS circuit 58 is identical to RMS circuit 48 except that RMS circuit 58 receives primary voltage. The output of RMS circuit 58 connects with computer 40. The values of a resistor 60 and a resistor 62 control whether the averaging circuit 46 receives primary voltage or primary current.
Secondary voltage is received from voltage meter 39 and passes through two operational amplifiers 64 and 65 (both typically TL032CP chips as manufactured by Texas Instruments of Dallas, Texas) and enters computer 40. Secondary current is received from current meter 34 and connects to computer 40. Computer 40 is detailed in Fig. 3. A multiplexer 66 of computer 40 receives data from input scaling and signal conditioner 28. Multiplexer 66 may typically com¬ prise an ADG508AKN chip such as manufactured by Analog Devices of Norwood, Massachusetts. Multiplexer 66 is connected directly to a logic means 72 and connected in series with a buffer 68, an A/D converter 70 and logic means 72. The buffer 68 may typically be a Texas Instruments TL032CP operational amplifier chip and the A/D converter 70 may typically comprise an AD573JN chip such as manufactured by Analog Devices of Norwood, Massachusetts. Logic means 72 is connected to SCR control circuit 24 and display 42, and is bi-directionally connected to input/output port 44 and bi- directionally connected to a memory means 74. Fig. 4 is a block diagram of a form factor meter as would be used as a stand¬ alone device. An external sensor 76 is connected to the input scaling and signal con- ditioner 28 which connects with computer 40, and computer 40 connects to display 42. A power source 78 will power input scaling and signal conditioner 28, computer 40 and display 42. Power source 78 may consist of circuitry allowing the form factor meter to plug into an external power source, or a battery or similar power supply. Sensor 76 may typically be a clamp as found on many models of current meters.
In operation, the primary embodiment of this invention is to work in coopera¬ tion with an electrostatic precipitator automatic voltage control device. A repre¬ sentative example of an electrostatic precipitator automatic voltage control is shown in my earlier patent U.S. Patent No. 4,605,424, issued August 12, 1986 and entitled 0 "Method and Apparatus for Controlling Power to an Electronic Precipitator", which is incorporated by reference herein. It should be recognized that, while these two in¬ ventions may share hardware, the problems addressed by each are distinct. The '424 patent controls voltage or power to the precipitator while this invention addresses the inefficiency of improperly sized components of an electrostatic precipitator. 5 Upon start up, input/output port 44 is utilized to communicate information to logic means 72 within computer 40. Communication may be accomplished through a built-in keyboard, portable lap-top computer, remote computer connected to the input/output port 44 directly or by modem, or by a similar means. Equipment size and power levels are communicated which allows initial calculations by logic means 72 to 0 determine the proper setting of CLR 16 and other settings for other equipment. CLR 16 and other equipment may be set automatically, or the appropriate values may be sent to display 42 and the equipment set manually — according to the previously cal¬ culated settings.
In addition to equipment size and power levels, the desired spark rate, SCR firing angle, fault conditions and all other information required by the automatic volt- 5 age control to supply power to the precipitator is communicated through input/out¬ put port 44 to logic means 72. This relieves the operator from having to manually set the equipment and helps to eliminate operator error. Information and calculated values required for future reference are sent from logic means 72 to memory 74.
The desired power level is sent from logic means 72, within computer 40, to 0 SCR control circuit 24 where the power level is converted into an SCR firing angle. Power is applied to precipitator 22 in terms of SCR firing angle degrees. The sinusoidal electrical cycle consists of 360 degrees, and consists of a positive half cycle and a negative half cycle with respect to polarity. Each SCR can be fired anywhere from 0 degrees to 180 degrees in the electrical cycle, 0 degrees being full power and 35 180 degrees being 0 power. When an SCR is fired at 45 degrees, for example, it will conduct from 45 degrees to 180 degrees. Therefore, a difference in firing angles can be represented as a distance along the abscissa of the sine wave. Due to polarity rever¬ sal, the SCR stops conducting at 180 degrees.
The normal operating state of SCR 1 and SCR 2 is 180 degrees which allows 0 power from power source 10 to pass through to precipitator 22. After SCR firing cir- cuit 24 translates the voltage level into the appropriate angle, this angle is sent to SCR 1 and SCR 2 which begins allowing the appropriate power to pass from power source 10 down line to step-up transformer 18 and full-wave rectifier 20, and eventually to precipitator 22.
SCR 1 and SCR 2 inherently produce sharp rises in power when their respec- tive firing angles dictate each SCR to energize. But, sharp increases in power create spark problems within precipitator 22. Thus, a primary object of CLR 16 is to filter and shape the signal leaving SCR 1 and SCR 2. Ideally, the shape of the secondary current filtered wave will be a broad, low wave form since the average value produces work and the peak value produces sparking. Ideally, the peak and average values of the signal entering precipitator 22 will be very close.
In addition, maximum power transfer is attained when load impedance matches line impedance. Precipitator 22 acts as a capacitor and CLR 16 acts as an in¬ ductor, therefore, if inductive CLR 16 is matched with capacitive precipitator load 22, the result will be a purely resistive load and maximum efficiency will occur. This is at- tained by measuring the form factor and sizing the equipment within the circuit to at¬ tain a form factor approaching 1.11.
Full-wave rectifier 20 converts the AC signal which passes through SCR 1 and SCR 2 into a pulsating DC signal. The positive output of full-wave rectifier 20 passes through current meter 34 and resistor 32 to ground. The negative output of full-wave rectifier 20 connects directly to precipitator 22 as well as through voltage dividing resis- tors 36 and 38 to ground. Voltage meter 39 is in series with metering resistor 36. Cur¬ rent meter 34 and voltage meter 39 are utilized to sense when sparking occurs in precipitator 22 and to sense fault conditions. The data obtained from voltage meter 39 and current meter 34 are sent to input scaling and signal conditioner 28 and even¬ tually to computer 40. Current transformer 26 measures the primary current and transformer 30 provides the primary voltage with respect to transformer 18. These values are sent to input scaling and signal conditioner 28 where they are converted to a state which al¬ lows the form factor to be calculated.
The circuitry that is principal to this invention can be found in Fig. 2. Primary current and voltage along with secondary current and voltage each enter input scaling and signal conditioner 28. Primary current from current transformer 26 is introduced and flows to averaging circuit 46 and RMS circuit 48.
The first half of averaging circuit 46 is a precision rectifier consisting of an operational amplifier 50 and two diodes 52 and 53. This precision rectifier provides a DC output that is not offset by the voltage drop of the diodes. A second operation¬ al amplifier 51 provides an averaging circuit such that the input of the total circuit 46 is AC and the output of the total circuit 46 is DC, proportional to the average value of the AC wave. The output of averaging circuit 46 is routed to computer 40.
The primary current also enters an RMS circuit 48. Operational amplifier 54 provides an input buffer and signal conditioning while RMS converter 56 changes the AC input to its RMS value and this value is routed to computer 40. Computer 40 now has primary current in two forms: average and RMS.
Transformer 30 provides primary voltage to input scaling and signal con¬ ditioner 28. The primary voltage enters RMS circuit 58 which changes the AC input to its RMS value, in the same manner as RMS circuit 48, and this value is routed to computer 40.
Two resistors 60 and 62 are provided. When resistor 60 is short and resistor 62 is open, the input scaling and signal conditioner 28 is configured to read the true RMS value and average value of the primary current for measuring form factor. By open- ing resistor 60 and shorting resistor 62, the true RMS value and average value of the primary voltage can be used to calculate form factor. At all times the true RMS of both primary voltage and primary current are provided. Resistors 60 and 62 allow the option of calculating either the average of the primary current or the average of the primary voltage so that the form factor can be calculated using either current or volt¬ age. Secondary current and voltage signals from circuitry associated with current meter 34 and voltage meter 39 both enter input scaling and signal conditioner 28. Secondary voltage passes through operational amplifiers 64 and 65 which provides isolation and scaling before it is routed to computer 40. The secondary current signal from resistor 32 is also routed to computer 40. Multiplexer 66 accepts each of the output signals of input scaling and signal conditioner 28. Upon a signal from logic means 72, multiplexer 66 allows one of the input signals from input scaling and signal conditioner 28 to pass. This signal passes through buffer 68, is converted to a digital signal at the A/D converter 70 and enters logic means 72. When logic means 72 receives both an RMS value and an average value for either primary current or primary voltage, the RMS value is divided by the average value to obtain the form factor. The form factor value is then transmitted to display 42. Display 42 can be a liquid crystal display or similar digital display, a CRT displaying the value graphically, a printed numerical or graphical representation or similar display. It is also understood that the form factor value can be transmitted to input/output port 44 and obtained remotely. An operator evaluates whether this form factor value is sufficiently close to the
1.11 ideal value. If not, equipment sizing is manually adjusted. It is also understood that this can be a closed loop system where the CLR 16 is automatically adjusted upon the determination of a poor form factor.
All four inputs to multiplexer 66 are retrieved and analyzed by logic means 72 rapidly and continuously. When logic means 72 determines that current meter 34 ex¬ perienced a sudden increase in current, a spark condition in precipitator 22 is analyzed. Upon determining a spark in precipitator 22, logic means 72 transmits information to SCR control circuit 24 to not energize again until the spark is extinguished. Since SCRs cannot shut off until a voltage level of 0 is received by them, up to an 8.33 mil- lisecond delay, CLR 16 limits the current to precipitator 22 until the SCRs actually stop conducting. The time delay before re-energizing and the procedure for deter¬ mining the appropriate firing angle with which to start energizing the SCRs is part of the automatic voltage control logic sequence and is detailed in the '424 patent.
The '424 patent also details how fault conditions are recognized and power shut down attained. But, in the '424 patent, determining what type of fault, the cause, specific location of the fault and potential solutions is left to the operator. The present invention incorporates diagnostic capabilities which greatly reduce down time. Therefore, computer 40 is fitted with non-volative memory 74, a device capable of retaining information when the power is removed. When the analog inputs to input scaling and signal conditioner 28 provide logic means 72 with a known fault condition, the information necessary to troubleshoot the precipitator 22, or its control circuits, and suggest corrective action can be retrieved from memory 74 and transmitted to dis¬ play 42. For instance, if the primary and secondary current is found to be very high and the primary and secondary voltage found to be very low, this indicates a short con¬ dition. The memory device containing its pre-programmed information informs the computer 40 of a short condition. Computer 40 then analyzes the condition, retrieves the proper wording for a short and the corrective measures pre-programmed into memory 74, and routes them to display 42.
A major problem with the prior art has been that automatic voltage controls are connected to a precipitator that operates on a number of voltages. The line volt- age is normally from 380-575 volts, 50-60 Hz. The secondary voltage is roughly 50,000 volts. The automatic voltage control runs on five (5) volts. The electrical supply is 120 volts. These diverse voltages create difficulties when isolating and protecting the circuitry from varying voltages.
For instance, a shorted primary to secondary transformer 18 can deliver damag¬ ing voltages. Therefore, a means must be available of protecting the automatic volt- age control that can be easily and quickly repaired. This invention provides the automatic voltage control with a plug-in input circuit board where all the scaling and over-voltage protection is contained. When the automatic voltage control is wired into the system, it does not have to be removed to be repaired. This results in sig¬ nificant time and cost reductions. The above mentioned form factor measurement can be a part of the automatic voltage control that controls the SCRs or can be developed as a separate testing device to measure the efficiency and proper sizing of electrostatic precipitator components. Fig. 4 shows a form factor meter as a stand-alone device. This device consists of sen¬ sor 76 which can typically be a clamp found on many present current transformers. Sensor 76 will sense the primary current of an electrostatic precipitator or similar device and provide this as an input to input scaling and signal conditioner 28. Input scaling and signal conditioner 28 will convert this current measurement to the average current and true RMS values. The true RMS value and average current value will be sent to computer 40 where the form factor calculations will be performed. Once the form factor is determined, this value will be transmitted to display 42 for the operator to read and analyze the efficiency of the equipment being measured. Power source 78 will be available to drive each of these components. As a stand-alone, portable device, this form factor meter will be valuable to quickly and safely determine the present operating efficiency of electrostatic precipitators and similar equipment.
From the foregoing it will be seen that this invention is one well adapted to at- tain all end and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the structure.
It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments may be made of the invention without ' departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Claims

Having thus described my invention, I claim:
1. An apparatus for measuring the form factor of a given circuit, said apparatus comprising: sensing means for sensing the current signal in said circuit; a conditioning circuit, connected to said sensing means, for conditioning said sensed signal into values utilized in calculating said form factor; said conditioning cir¬ cuit including means for changing said sensed signal to its average value, and means for changing said sensed signal to its RMS value; a computer connected to said conditioning circuit for calculating said form fac- tor value; said computer including a multiplexer for accepting and distinguishing said average signal and said RMS signal, an analog to digital converter connected to said multiplexer, and logic means with memory connected to said multiplexer and said analog to digital converter; said logic means including means of retrieving said digital average value from said multiplexer, means of retrieving said digital RMS value from said multiplexer, and means of dividing said RMS value by said average value to ob¬ tain the form factor value; a display means, connected to said computer, for visually displaying said form factor value determined by said computer; and a source of electrical power connected to said conditioning circuit, said com- puter, and said display means.
2. An apparatus as in claim 1, wherein said sensing means senses the voltage signal in said circuit.
3. An apparatus as in claim 2, wherein said sensing means senses both the cur¬ rent signal and the voltage signal in said circuit; said conditioning circuit further including means to change the sensed voltage signal and the sensed current signal into their average value and RMS value; and said logic means further including means to divide said RMS value by said average value to obtain said form factor value using both said voltage signal and said current signal.
4. An apparatus as in claim 3, including an input/output port connected to said computer means; and said logic means further including means to transmit said form factor value to said input/output port.
5. An apparatus for measuring the form factor in cooperation with an automatic voltage control on an electrostatic precipitator comprising: a source of electrical power; a transformer/rectifier set connected between said power source and said precipitator; means for varying said electrical power connected between said source of power and said transformer/rectifier set; means for sensing the primary electrical characteristics after said means for varying the electrical power and before said transformer/rectifier set; means for detecting the secondary electrical characteristics after said trans¬ former/rectifier set and before said precipitator; a conditioning circuit, connected to said means for sensing and said means for detecting to condition said sensed and detected electrical characteristics for calcula¬ tion of said form factor and determination of sparking in said precipitator; said con¬ ditioning circuit including means for changing said sensed characteristics to their average values, means for changing said sensed characteristics to their RMS values, and means for scaling and detecting secondary electrical characteristics; computer means, connected to said conditioning circuit and said means for varying said electrical power, for calculating the form factor, determining when a spark occurs and controlling said means for varying said electrical power in response to the occurrence of a spark, so that the power to said precipitator is varied; said computer including a multiplexer for accepting from said conditioning circuit and distinguish- ing said average sensed signal, said RMS sensed signal and said detected secondary characteristics, an analog/digital converter connected to said multiplexer, and logic means with memory connected to said analog/digital converter and said multiplexer; said logic means including means of retrieving said digital average value from said multiplexer, means of retrieving said digital RMS value from said multiplexer, means of dividing said RMS value by said average value to obtain the form factor value, and means of retrieving said detected secondary electrical characteristics and determin¬ ing the occurrence of a spark in said precipitator; memory means for storing pre-determined rates of energization, spark rates, and calculations to determine proper firing angles; means responsive to the occurrence of said spark for controlling said means for varying said electrical power to reduce power to said precipitator to 0; means for automatically adjusting said means for varying said electrical power according to pre-determined criteria stored in said memory which controls when and at what rate to begin allowing power to pass said means for varying said electrical power to said precipitator; and a display means, connected to said computer, for visually displaying said form factor value determined by said computer.
6. An apparatus as in claim 5, wherein said sensing means includes means to sense primary current and primary voltage, said conditioning circuit includes means to change the sensed voltage signal and the sensed current signal into their average value and RMS value, and said logic means includes means for calculating the form factor using both primary current and primary voltage values.
7. An apparatus as in claim 6 to recognize circuit fault conditions and to de- energize said electrostatic precipitator upon detection of a fault condition, said ap¬ paratus further comprising: means for storing pre-determined fault conditions in said memory; means for storing potential causes and solutions to said fault conditions in said memory; and said logic means includes means of determining said fault conditions, and de- energizing said electrostatic precipitator upon determination of a fault condition; said logic means further includes means to analyze said fault conditions, means to retrieve the corrective measures pre-programmed into memory for the appropriate fault, and means to route said corrective measures to said display.
8. An apparatus as in claim 7 including an input/output port connected to said computer, and wherein said logic means includes means to transmit said form factor value and other operating conditions to said input/output port, and means to receive from said input/output port initial operating conditions, fault conditions, initial electri¬ cal equipment sizing and other information necessary for the start-up and operation of said electrostatic precipitator.
9. An apparatus as in claim 7 including a removable plug-in circuit board on which is mounted all said means for scaling and over-voltage protection in order to facilitate removal and repair.
10. An apparatus for detecting fault conditions of an electrostatic precipitator comprising: a source of electrical power; a transformer/rectifier set connected between said power source and said precipitator; means for varying said electrical power connected between said source of power and said transformer/rectifier set; means for sensing the primary electrical characteristics after said means for varying the electrical power and before said transformer/rectifier set; means for detecting the secondary electrical characteristics after said trans- former/rectifier set and before said precipitator; a conditioning circuit, connected to said means for sensing and said means for detecting to condition said sensed and detected electrical characteristics for deter¬ mination of sparking in said precipitator; said conditioning circuit including means for scaling and detecting secondary electrical characteristics; computer means, connected to said conditioning circuit and said means for varying said electrical power, for determining when a spark occurs and controlling said means for varying said electrical power in response to the occurrence of a spark, so that the power to said precipitator is varied; said computer including a multiplexer for accepting electrical characteristics signal from said conditioning circuit, an analog/digital converter connected to said multiplexer, and logic means with memory connected to said analog/digital converter and said multiplexer; said logic means in¬ cluding means of retrieving said detected secondary electrical characteristics and determining the occurrence of a spark in said precipitator; memory means for storing pre-determined rates of energization, and spark rates; means responsive to the occurrence of said spark for controlling said means for varying said electrical power to reduce power to said precipitator to 0; means for automatically adjusting said means for varying said electrical power according to pre-determined criteria stored in said memory which controls when and at what rate to begin allowing power to pass said means for varying said electrical power to said precipitator; and a display means, connected to said computer, for visually displaying said form factor value determined by said computer.
11. An apparatus as in claim 10 to recognize circuit fault conditions and to de- energize said electrostatic precipitator upon detection of a fault condition, said ap- paratus further comprising: means for storing pre-determined fault conditions in said memory; means for storing potential causes and solutions to said fault conditions in said memory; and said logic means includes means of determining said fault conditions, and de- energizing said electrostatic precipitator upon determination of a fault condition; said logic means further includes means to analyze said fault conditions, means to retrieve the corrective measures pre-programmed into memory for the appropriate fault, and means to route said corrective measures to said display.
PCT/US1989/005430 1989-11-30 1989-11-30 Electrical control system for electrostatic precipitator WO1991008052A1 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
PCT/US1989/005430 WO1991008052A1 (en) 1989-11-30 1989-11-30 Electrical control system for electrostatic precipitator
EP90911823A EP0504143B1 (en) 1989-11-30 1990-06-29 Electrical control system for electrostatic precipitator
CA002069881A CA2069881C (en) 1989-11-30 1990-06-29 Electrical control system for electrostatic precipitator
DE69030583T DE69030583T2 (en) 1989-11-30 1990-06-29 ELECTRICAL CONTROL DEVICE FOR ELECTROSTATIC SEPARATORS
DK90911823.4T DK0504143T3 (en) 1989-11-30 1990-06-29 Electrical control system for an electrostatic separator.
PCT/US1990/003714 WO1991008053A1 (en) 1989-11-30 1990-06-29 Electrical control system for electrostatic precipitator

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PCT/US1989/005430 WO1991008052A1 (en) 1989-11-30 1989-11-30 Electrical control system for electrostatic precipitator

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4486704A (en) * 1981-07-28 1984-12-04 Flakt Aktiebolag Control device for an electrostatic dust separator
US4605424A (en) * 1984-06-28 1986-08-12 Johnston David F Method and apparatus for controlling power to an electronic precipitator

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3873282A (en) * 1972-07-27 1975-03-25 Gen Electric Automatic voltage control for an electronic precipitator
CA1089002A (en) * 1976-08-13 1980-11-04 Richard K. Davis Automatic control system for electric precipitators
US4290003A (en) * 1979-04-26 1981-09-15 Belco Pollution Control Corporation High voltage control of an electrostatic precipitator system
US4587475A (en) * 1983-07-25 1986-05-06 Foster Wheeler Energy Corporation Modulated power supply for an electrostatic precipitator
US4860149A (en) * 1984-06-28 1989-08-22 The United States Of America As Represented By The United States National Aeronautics And Space Administration Electronic precipitator control
JPS6125650A (en) * 1984-07-17 1986-02-04 Sumitomo Heavy Ind Ltd Method for controlling electrical charge of electrical dust precipitator
DK552186A (en) * 1986-11-19 1988-05-20 Smidth & Co As F L METHOD AND APPARATUS FOR DETECTING RETURN RADIATION IN AN ELECTROFILTER WITH GENERAL OR INTERMITTING POWER SUPPLY

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4486704A (en) * 1981-07-28 1984-12-04 Flakt Aktiebolag Control device for an electrostatic dust separator
US4605424A (en) * 1984-06-28 1986-08-12 Johnston David F Method and apparatus for controlling power to an electronic precipitator

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DE69030583D1 (en) 1997-05-28
EP0504143B1 (en) 1997-04-23
EP0504143A1 (en) 1992-09-23
EP0504143A4 (en) 1992-10-07
DK0504143T3 (en) 1997-06-30
DE69030583T2 (en) 1997-08-07
WO1991008053A1 (en) 1991-06-13
CA2069881C (en) 1996-11-26

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