FIELD OF INVENTION
The invention relates to a control system of electrostatic precipitator used for air
pollution control in large plants like thermal power, cement, fertilizer, steel, chemicals
etc. More particularly, the invention relates to an electronic apparatus for controlling
energisation , both three phase & single phase linear power supply, inbuilt rapping
motor, multi master communication protocols and remote monitoring, wireless
interface, user interface through a keypad & LCD display used in the control system of
an electro static precipitator.
BACKGROUND & PRIOR ART
Electrostatic precipitation is one of the most effective processes to control air pollution
generated by the industrial emissions. The method which has proved to be highly
effective in controlling air pollution, is used for removal of undesirable matter from a
gas stream by electrostatic precipitation. Electrostatic precipitator (hereafter referred to
as ESP) is an air pollution control device designed to electrically charge and collect
particulates generated from industrial processes such as those occurring in power
plants, cement plants, pulp & paper mills and utilities. Electrostatic dust removing basic
working principle is that when the dust laden gas flow through the high voltage static
electric field inside ESP, dust is charged due to collisions with the positive and negative
ions. Under the action of the electric field the charged dust particles moves to

oppositely charged electrode plates, viz., discharge electrode and collection plate and
gets eventually absorbed, thus achieving dust collecting effect. During continuous
operation of an electrostatic precipitator, the dust from the collector plates and
discharge electrodes must be periodically removed for further conveying of the collected
dust. Dust on the electrodes are periodically removed by rapping/hitting the electrodes
with mechanical hammers controlled by rapping motors. The rapping mechanism is
critical to ESP efficiency and so is controlled automatically by a dedicated controller or
by ESP Power supply controller itself.
In the ESP, the electrostatic precipitation is achieved by controlling a high voltage transformer
rectifier (hereafter referred to as HVR) set by a dedicated ESP electronic controller
(hereafter referred as EC). An ESP installation consists of a plurality of fields, each field being
individually energized and controlled by a dedicated ESP controller. The ESP fields are arranged
in pass-wise along the gas flow direction. Typically, the EC and the HVR are placed at different
locations in a plant due to operating requirements. In the ESP, the efficiency of the system
mainly depends on the energisation of ESP fields. The most widely used energisation of
ESP is by a single phase mains frequency silicon controlled rectifier power supply. Then
came the three phase power frequency silicon controlled rectifier power supply. The
latest being is insulated gate bipolar transistor (herein after referred as IGBT) controlled
high frequency high voltage switch mode power supply (hereafter referred as SMPS).
All these three power supply system for ESP are having its own advantages and

disadvantages and the selection of power supply system vary from case to case. Each
of these systems have its own control system for optimum operation and monitoring
and requires dedicated and customized controllers to cater to the specific control and
monitoring inputs and outputs of each of the power system for ESP.
In the prior arts, electronic controllers (EC) exist to control the thyrlstor based line
frequency single phase linear power supply systems of ESP. They are meant only for
that particular system and hence can not be used to control a three phase power supply
system for ESP energisation. Similarly, there exists dedicated ECs for three phase
supply and for wireless ESP energisation control.
The prior art, for example, 1353KOL2013-CS claims a versatile electronic controller for
different power supply systems of an electrostatic precipitator. The referred controller
does not have a user interface for manual input of commands or display of ESP
parameters. Hence a separate module is required for providing the inputs. The
controller architecture is not based on the ARM (Acorn RISC Machine) processor but on
DSP (digital signal processor) based microprocessor. The prior art controller has CAN
(Controller Area Network) protocol based communication but does not have Ethernet
based communication protocol. Other prior arts for ESP controller lack a common
controller/EC which can cater to the control needs of line frequency single phase and

three phase thyristor controlled power supply systems through wireless with in-built
rapping mechanism.
OBJECTS OF THE INVENTION
Therefore the object of the invention is to propose a composite EC which can cater to
the control needs of line frequency single phase and three phase thyristor controlled
power supply systems for ESP. This will eliminate the maintenance and support system,
development set up etc. for separate controllers. Maintenance of a single EC is far more
comfortable than maintaining and supporting separate ECs for each application.
Another object of the invention is to propose a wireless system based on Zigbee
protocol for control of EC HVR which can eliminate all signal and control cables that run
from the EC panel to ESP-HVR. This can reduce enormous amount of cable that run
from the EC panel to ESP-HVR. This can reduce enormous amount of cable used for EC-
HVR control.
A still another object of the invention is to propose an ESP controller/EC with in-built
rapping and heater control which means the software & hardware is built in to each
individual controller having no separate controller for rapping control.

Yet another object of the invention is to propose an ESP controller architecture based
on ARM cortex processor core for faster and much reliable operation, ARM is a generic
processor which can be adopted by any manufacturer and hence finding a suitable
substitute or replacement will be easier. The processor's IP is shared by with all leading
semiconductor manufacturers of the world and hence changing of software from one
platform to another is easy.
A further object of the invention is to propose a versatile ESP controller/EC with CAN
based multi master communication and also Ethernet protocol for remote monitoring
and control.
The final object of the invention is to propose an EC with all the above features and
having a keypad for manual input of commands and LCD for display of ESP parameters.
SUMMARY OF THE INVENTION
Accordingly, there is provided a versatile EC capable of controlling line frequency single
phase and three phase thyristor controlled power supply systems having both Zigbee
protocol based wireless interface and wired communication (CAN and Ethernet) with in-
built rapper and heater control.

The invented EC has hardware and the associated software with user interface for
controlling ESP energisation, spark/ark detection and quenching, back corona detection
and suppression.
The invented EC further has hardware and associated software for controlling each
phase separately for a three phase power supply system for an ESP.
The invented EC also has hardware and associated software for initiating control action
based on the feedbacks (hardwired as well as wireless) i.e. ESP(output) current and
voltage, HVR primary and secondary voltages and current, alarms and fault indications
etc.
The hardware and the associated software of the EC are enabled to perform control and
monitoring of rapping motors as well as heaters.
The invented EC also has a multi master protocol based CAN communication network
for peer to peer communication as well as remote monitoring and control.
The invented EC also has Ethernet based communication module for remote monitoring
ancl control.
The invented EC also has Zigbee based wireless communication interface for feedback
signals.

RRIEF DESCPTimnN OF THF ^rmMPANYINfi DRAWINGS
Rg.l is hardware block diagram of the electronic controller(EC) of the ESP comprising
of the following :
Block (1): ARM processor
Block(2) : An interface connecting the feedback signals from EC panel to the processor
Block(3) : An interface connecting the different alarm signals coming from the power
supply system for ESP to the processor
Block(4) : An interface for coupling the rapping motor and heater status signals
Block(5) : Standard JTAG interface for loading the control logic/software code
Block (6): CAN communication interface
Block (7): An Ethernet communication interface
Block (8): Power supply unit.
Block (9): An user interface comprising keypad and LCD
Block (10): Zigbee communication module
pFW, Fp nPSTRlPTION OP THF PREFERRED EMBODIMENT OF THE INVENTION
The three phase ESP controller (EC) receives the feedback signals for decoding and
executing the software methods to control line frequency single phase and three phase
thyristor controlled power supply system.

In Fig.l, Block (8) is a power supply unit for the EC which provides power for the
controller and the peripheral devices.
Block (1) is the central ARM processor which executes the software methods for
feedback control of ESP. It has provisions to take analog and digital signals as feedback
and also giving out control signals based on input signals for controlling ESP. It has
inbuilt memory to store the program (control logic) executing the software methods to
implement the feedback control for ESP energisation, spark/arc detection and
quenching, back corona detection and suppression based on ESP voltage and current
parameters as feedback. It has provision to get status feedback from rapping motor
and heater operations executing the software methods to control the rapping & heater
operations. It has inbuilt CAN communication module and also the ethernet module for
remote monitoring and control through a multi master communication network.
Block (2) is an interface connecting the feedback signals for ESP and HVR current and
voltage, to the processor.
Block (3) is an interface connecting the different alarm signals of transformers,
overloads, fault indications etc. coming from the power supply system for ESP to the
processor(l).

Block (4) is an interface for coupling the rapping motor and heater status signals from
the corresponding systems to the processor of EC. It also couples the ON/OFF
commands from processor to the rapping motors and heaters.
Block (5) is a standard JTAG (Joint Test Action Group) interface for loading the control
logic/software code in to the inbuilt memory of the processor.
Block (6) is a CAN communication interface for connecting the EC with any remote
monitoring and control system through the CAN communication network.
Block (7) is an Ethernet communication interface for connecting the EC any remote
monitoring and control system through ethernet.
Block (9) is user interface comprising of keypad and LCD for providing input commands
to the processor and display of system parameters.
Block (10) is Zigbee communication module used for wireless communication interface
between HVRs and the ECs.

WE CLAIM
1) A novel wireless composite electronic controller, for power supply, energisation, and
feedback control of Electro static precipitator characterized by the following
features.
• Controlling both line frequency single & three phase power supply
• Wireless control system for EC-High Voltage Rectifier
• In-Built rapping & heater control of the ESP
• Processor for faster & reliable operation
• Multi master CAN communication and Ethernet protocol for remote
monitoring and control
• Display of multiple parameters and feedbacks and control commands
through User interface

2) The EC of ESP as claimed in claim 1, wherein the central ARM processor 1 is
provided to execute the software methods for feedback control of ESP taking both
analog & digital signals in the process of ESP energisation, spark/arc detection and
quenching, back corona detection and suppression based on ESP voltage and
current parameters as feedback
3) The EC of ESP as claimed in claim 1, wherein, an interface 2 for coupling HVR-
secondary feedback signals, HVR alarm signals, primary input current and voltage
feedback to the processor 1 of the controller.

4) The EC of ESP as claimed in claim 1, wherein, an interface 3 connecting the different
alarm signals of faults coming from the power supply system from ESP to the
processor 1
5) The EC of ESP as claimed in claim 1, wherein, an interface 4 for coupling the rapping
motor and heater status signals from the corresponding systems to the processor 1
and also coupling ON/OF commands from processor to the rapping motors and
heaters

6) The EC of ESP as claimed in claim 1, wherein, an interface 5 for loading the control
logic/software code in to the memory of the processor 1
7) The EC of ESP as daimed in claiml, wherein, CAN communication interface 6 for
.connecting the EC with any remote monitoring and control system through the CAN
communication network
8) The EC of ESP as claimed in claim 1, wherein, an ether net communication network
7 for connecting the EC with any remote monitoring and control system through the
CAN communication network
9) The EC of ESP as claimed in claim 1, wherein, user interface 9 comprising of KEY
PAD and LCD for providing input commands to the processor and display of the
system parameters

10)The EC of ESP as claimed in claiml, wherein, the module 10 used for wireless
communication between HVR and the EC
11)A method of controlling power supply, energisation, feedback control and monitoring
system of the operating parameters, e.g; voltage, current, fault conditions, if any, of
an electrostatic precipitator characterized by,
• Control of both line frequency single & three phase power supply
• Wireless control system for EC-High Voltage Rectifier
• in-built rapping & heater element control
• Remote monitoring and control of multi-master CAN communication and
Ethernet protocol
. Feedback control of multiple parameters and display through user interface
and commands