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1. (WO1991006371) MULTIPLE RAPPER CONTROL FOR ELECTROSTATIC PRECIPITATOR
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Having thus described our invention, we claim:
1. A multiple rapper control for an electrostatic precipitator, said rapper control comprising:
a plurality of electrostatic precipitator rappers;
a TRIAC switch device having a plurality of TRIACs wherein each said rapper is connected to at least one of said TRIACs;
power control means with an output connected to said TRIAC switch device to vary the input power to each said rapper;
a power source connected to said power control means to supply input power to said power control means;
current detecting means connected to said output of said power control means to sense and measure the peak electrical input current to each said rapper;
a computer with memory means connected to said current detecting means, to said power control means and to said TRIAC switch device for storing a look-up table including the operating characteristics of each said rapper; and
logic means stored in said computer to control power to each said rapper in a preselected logic sequence.
2. The multiple rapper control as in Claim 1, wherein said look-up table of operating characteristics of each said rapper comprises the pre-set electrical input cur-rent, the minimum increment between energization cycles, and the maximum duration of energization.
3. The multiple rapper control as in Claim 2, said logic sequence comprising: retrieving from said memory said increment between said energization cycles and determining the appropriate time to begin energizing each said rapper;
retrieving from memory said duration of energization and said pre-set electri-cal input current characteristic;
sending to said power control means appropriate information to pass rapper current from said power source substantially similar to said pre-set electrical input characteristic;
sending to said power control means appropriate information to determine the completion of said energization cycle and to cease energization of each said rapper at that time;
sending to said TRIAC switch device appropriate information to allow current to flow to each said rapper;
sending to said current detecting means appropriate information to sense, measure, and hold the actual peak electrical input current to each said rapper;

retrieving from said current detecting device said measurement of the actual peak electrical input current to each said rapper, and converting said measurement to a digital word;
comparing said digital word with said pre-set stored electrical input current characteristic;
sending to said power control means appropriate information, accounting for required adjustments based on said comparison, to pass rapper current from said power source substantially similar to said pre-set electrical input current characteristic,
the sequence of retrieving from said current detecting means said measurement of actual rapper input current, converting said measurement to said digital word, comparing said digital word to said pre-set electrical input current characteristic, and sending appropriate information to said power control means is repeated until said energization cycle is complete; and
determining the completion of said energization cycle and sending appropriate information to said TRIAC switch device to de-energize said rapper.
4. The multiple rapper control as in Claim 3, wherein each of said digital words representing said measured rapper input current is stored at a different address within said memory allowing present and past operating conditions of each said rapper to be available to an operator.
5. The multiple rapper control as in Claim 4 wherein open and short circuit fault conditions are determined and each said rapper is automatically de-energized in such cases, said rapper control including:
pre-set open and short trip conditions stored in said look-up table; and
said logic sequence adapted to retr *ve said open and short trip conditions from said look-up table and compare said digital word, representing actual peak rapper input current, with said pre-set open and short trip conditions to determine a fault condition, and to send appropriate information to said power control means to de-energize each said rapper upon fault detection; and
said computer having logic means to avoid re-energizing each said rapper with fault in the future.
6. The multiple rapper control as in Claim 5, wherein a fault condition is recognized and each said rapper is de-energized within one-half cycle to assure maximum circuit protection.
7. The multiple rapper control as in Claim 3, wherein said look-up table of operating characteristics includes the location of each said rapper, and is stored in said look-up table; and said logic sequence includes receiving said location of each said rapper and sending said TRIAC switch device appropriate information to energize said rapper, and sending said digital word, representing peak rapper input current, to an appropriate address within said memory to allow an operator to determine which digital words correspond with each said rapper.
5 8. The multiple rapper control as in Claim 1, wherein said power control means comprises:
an SCR firing circuit connected to said computer;
an inverse parallel SCR combination connected to said SCR firing circuit; and a full-wave bridge rectifier connected to said inverse parallel SCR combina-0 tion and said power source.
9. The multiple rapper control as in Claim 1, wherein said current detecting means comprises:
one sense resistor connected serially between said power means and said

TRIAC switch device;
5 an isolation amplifier connected across said sense resistor;
a precision rectifier serially connected to said isolation amplifier; and
a sample and hold peak detector serially connected to said precision rectifier and bi-directionally connected to said computer.
10. The multiple rapper control as in Claim 3, wherein said computer com-0 prises a master computer with memory and a slave computer with memory, said memory of said master computer comprising said look-up table and said stored digital words containing trending information, and said master computer having logic means to determine when a particular rapper is to be energized and communicating appropriate information to said slave computer with memory, and said memory of said slave computer receives appropriate information from said master computer, corresponding to the specific rapper to be energized, to allow said logic sequence to be performed on each said rapper with said information is stored in memory of said slave computer until the energization cycle of said specific rapper is complete, and said slave computer having logic means to retrieve appropriate information from memory of said slave computer and to perform said logic sequence and to communicate appropriate 0 information to said master computer with memory.
11. The multiple rapper control as in Claim 1 including:
a voltage selection relay having voltage selection relay contacts connected between said power source and said power control means to select the voltage level exiting said power source; and
5 an AC/DC relay having AC/DC relay contacts connected between said power control means and said TRIAC switch device to select the voltage type which enters said TRIAC switch device.
12. The multiple rapper control as in Claim 11, wherein said look-up table of operating characteristics of each said rapper comprises the voltage type, the voltage level, the pre-set electrical input current, the minimum increment between energization cycles, and the maximum duration of energization.
13. The multiple rapper control as in Claim 12, said logic sequence comprising:
retrieving from said memory said increment between said energization cycles and determining the appropriate time to begin energizing each said rapper;
retrieving from said memory said voltage type and said voltage level;
sending to said voltage selection relay information to arrange said voltage selection relay contacts to allow the proper voltage level to exit said power source; sending to said AC/DC relay information to allow the proper voltage type to enter said TRIAC switch device;
retrieving from memory said duration of energization and said pre-set electrical input current characteristic;
sending to said power control means appropriate information to pass rapper current from said power source substantially similar to said pre-set electrical input characteristic;
sending to said power control means appropriate information to determine the completion of said energization cycle and to cease energization of each said rapper at that time;
sending to said TRIAC switch device appropriate information to allow current to flow to each said rapper;
sending to said current detecting means appropriate information to sense, measure, and hold the actual peak electrical input current to each said rapper;
retrieving from said current detecting device said measurement of the actual peak electri 'nput current to each said rapper, and converting said measurement to a digital wor╬▒,
comparing said digital word with said pre-set stored electrical input current characteristic;
sending to said power control means appropriate information, accounting for required adjustments based on said comparison, to pass rapper current from said power source substantially similar to said pre-set electrical input current characteristic, the sequence of retrieving from said current detecting means said measurement of actual rapper input current, converting said measurement to said digital word, comparing said digital word to said pre-set electrical input current characteristic, and sending appropriate information to said power control means is repeated until said energization cycle is complete; and
determining the completion of said energization cycle and sending appropriate information to said TRIAC switch device to de-energize said rapper.
14. The multiple rapper control as in Claim 13, wherein each of said digital words representing said measured rapper input current is stored at a different address within said memory allowing present and past operating conditions of each said rapper to be available to an operator.
15. The multiple rapper control as in Claim 14 wherein open and short circuit fault conditions are determined and each said rapper is automatically de-energized in such cases, said rapper control including:
pre-set open and short trip conditions stored in said look-up table; and
said logic sequence adapted to retrieve said open and short trip conditions from said look-up table and compare said digital word, representing actual peak rapper input current, with said pre-set open and short trip conditions to determine a fault condition, and to send appropriate information to said power control means to de-energize each said rapper upon fault detection; and
said computer having logic means to avoid re-energizing each said rapper with fault in the future.
16. The multiple rapper control as in Claim 15, wherein a fault condition is recognized and each said rapper is de-energized within one-half cycle to assure maximum circuit protection.
17. The multiple rapper control as in Claim 13, wherein said look-up table of operating characteristics includes the location of each said rapper, and is stored in said look-up table; and said logic sequence includes receivmg said location of each said rapper and sending said TRIAC switch device appropriate information to energize said rapper, and sending said digital word, representing peak rapper input cur-rent, to an appropriate address within said memory to allow an operator to determine which digital words correspond with each said rapper.
18. The multiple rapper control as in Claim 11, wherein said power control means comprises:
an SCR firing circuit connected to said computer;
an inverse parallel SCR combination connected to said SCR firing circuit; and a full-wave bridge rectifier connected to said inverse parallel SCR combination and said power source.
19. The multiple rapper control as in Claim 11, wherein said current detecting means comprises:
one sense resistor connected serially between said power means and said

TRIAC switch device;
an isolation amplifier connected across said sense resistor;
a precision rectifier serially connected to said isolation amplifier; and
a sample and hold peak detector serially connected to said precision rectifier and bi-directionally connected to said computer.
20. The multiple rapper control as in Claim 13, wherein said computer comprises a master computer with memory and a slave computer with memory, said memory of said master computer comprising said look-up table and said stored digital words containing trending information, and said master computer having logic means to determine when a particular rapper is to be energized and communicating appropriate information to said slave computer with memory, and said memory of said slave computer receives appropriate information from said master computer, corresponding to the specific rapper to be energized, to allow said logic sequence to be performed on each said rapper with said information is stored in memory of said slave computer until the energization cycle of said specific rapper is complete, and said slave computer having logic means to retrieve appropriate information from memory of said slave computer and to perform said logic sequence and to communicate appropriate information to said master computer with memory.