FIELD OF INVENTION
The invention relates to monitoring and controlling of electrostatic precipitator
used for air pollution control. More particularly, the invention relates to a device
for monitoring and controlling of electrostatic precipitator. The invention further
relates to an associated method.
BACKGROUND OF THE INVENTION
Electrostatic precipitator is one of the most effective ways to control air pollution
generated by industrial emission. This technique, which has proven highly
effective in controlling air pollution, has been used for removal of undesirable
matter from a gas stream by electrostatic precipitation. Electrostatic precipitator
(hereinafter 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 and paper mills and
utilities etc. The electrically charged particles are attracted towards electrode and
collection plate. ESP is divided into a plurality of fields depending on the dust
load. A field is considered healthy as long as it is charged with sufficient voltage
and current between its discharge and collection plate. During continuous
operation of an electrostatic precipitator, the dust from collector plates and
discharge electrodes must be periodically removed for further conveying of the
colleted dust.

Typically, energizing ESP field requires a very high voltage to the tune of 40 to
90 KV DC to be generated from the available AC sources. This involves stepping
up of AC voltage and rectifying to produce a very high voltage. Also, the
generated high voltage shall be maintained and controlled during the operation
of the ESP field. This is generally being achieved by High Voltage Rectifier with
electronic controllers (EC-HVR). The ESP fields are arranged in pass-wise along
the distribution of gas flow direction. For a typical larger ESP, there will be
around 8 pass's and each pass will have around 8 fields depending on the size of
ESP totaling 64 EC-HVRs.
In the prior art, mechanism exits to integrate all EC-HVR controllers through a
communication network and operate them from a single point, which is basically
a computer. The computer normally is placed at main plant control room and any
observation or controlling to be done on EC-HVRs has to be done only from the
main control room. In the prior art, there exists a mechanism to monitor the
parameters from within same EC-HVR textually, but no mechanism exists to
monitor the parameters graphically.
In the prior art, the communication protocol used between EC-HVR and
computer is a custom protocol and they cannot be directly interfaced to plant-
wide computer, which will not be enabled with all custom protocols. There exists
no mechanism to interface all EC-HVR controllers through an open standard
based communication protocol for easy interface to any controller, which is
supporting open standard based communication.

OBJECTS OF THE INVENTION
The invention seeks to provide an improved method to monitor various
parameters of the ESP viz., electrical voltage and electrical current between
electrodes, current position of all rappers with respect to gas flow, healthiness of
the fields, and overall dust load into ESP.
It is therefore an object of the invention is to propose a device for monitoring
and controlling of electrostatic precipitator which monitors key parameters by
real-time trending at the field control panels.
Another object of the invention is to propose a device for monitoring and
controlling of electrostatic precipitator which eliminates the need of the user to
reach out central ESP control system for such real-time trending.
A still another object of the invention is to propose a device for monitoring and
controlling of electrostatic precipitator which enables the EC-HVRs to get
interfaced directly to the central computer of the plant.
Yet another object of the invention is to propose a device for monitoring and
controlling of electrostatic precipitator which enables configuration of a device
with less number of electronic components for increased reliability.

A further object of the invention is to propose a device for monitoring and
controlling of electrostatic precipitator which ensures field programmability of the
device for any future upgradation.
A still further object of the invention is to propose a device for monitoring and
controlling of electrostatic precipitator which has a graphical user interface for
easy understanding and configuration of process parameters.
A yet further object of the invention is to propose a device for monitoring and
controlling of electrostatic precipitator which improves the reliability and
availability of communication using peer-to-peer communication, multi-master
communication and periodical communication from HVR controllers.
SUMMARY OF THE INVENTION
Accordingly, there is provided a device for controlling and monitoring an
Electrostatic precipitator (ESP) comprising at least one of Graphical Operator
Terminal (GOT) which communicates over a Controller Area Network (CAN) in a
multi-master communication protocol with a plurality of HVR controllers (8)
through an open standard bus, and operably connected to a central computer
(7), characterized in that the GOT comprises a single micro-controller (1) and
enabled to control the communication between the HVR controllers (8) and the
GOT such that all the HVR controllers (8) transmit their status over the open
standard bus (5) at a periodical interval, and the GOT receives the data and
update its database for user presentation and in that the GOT transmitting

invention, is configured by adapting a single chip micro-controller with associated
peripheral passive components. It is intended to be mounted on first or last
ECHVR control panel of each pass of an ESP. But it can also be mounted on any
EC-HVR panels if required. It has a graphical CD to display required parameter
to be monitored.
Each GOT is connected to CAN network, an open standard based bus protocol,
with all EC-HVR controllers. The operator can select any EC-HVR to be controlled

and monitored by entering the required EC-HVR address in the user interface.
Upon selection, the status of all required parameters of EC-HVR would be made
available to the user. The communication between GOT and EC-HVR controllers
is a continuous phenomenon as the EC-HVR will transmit its status over the
network periodically. This is also applicable to other EC-HVRs to know the status
of its peer.
The GOT can be directly connected to a central computer through the same CAN
network. The central computer needs to contact only the respective GOT for the
entire pass-wise data instead of individually contacting all HVR controllers. This
will reduce load on central computer as well as on HVR controllers.
The invention will now be described in detail with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 is a block diagram illustrating the processor schematics of
microprocessor-based controller with pre-defined parameters stored in memory.
Figure 2 is a block diagram illustrating communication bus scheme.

DETAIL DESCRIPTION OF THE INVENTION
The invention discloses a graphical operator terminal, which specially deals with
better operation of ESP for a power plant or process plant. The GOT is equipped
with 240 x 128 pixel graphical LCD and the user interface screens are presented
to the user. The user will select to monitor and control the respective HVR. The
GOT enables the operator further to monitor the trend of an available parameter
over a time period.
Each GOT is connected to all HVR controllers through CAN based bus network.
One GOT is attached to the first or last HVR controller panel of each PASS of
ESP. The user can reach any HVR controller in a GOT though it is physically
located at each PASS.
The HVR controllers will send their status frames at periodic intervals over CAN
network. This will be received by all GOT and other HVR controllers in the
network. Each HVR maintain the ON/OFF status of other HVR controllers. Upon
receiving the status of all HVR controllers, the GOT will update its database. The
GOT responds central computer for any HVR controller status.
In the block diagram shown in figure 1, a microcontroller (1) is connected to the
buzzer and address selection block (3) through a data bus and control bus. The
buzzer (3) will annunciate for any for any alarm and address selection will decide

the position each or a plurality of GOTs. The microprocessor (1) is also
connected to a communication interface (2), which acts as a interface between
the GOTs, the HVR controllers and the central computer of ESP. The monitored
data are communicated to the GOT through this communication interface (2). On
receipt of such parameters, the GOT updates its database. This will be further
communicated to the central computer on request. The microcontroller is also
connected to a display (4), through which data are presented in text and
graphical form.
In the block diagram shown in figure 2, the communication schematic is
depicted. Each GOT (6) is connected to the HVR controllers (8) through a CAN
(5) communication bus. Also, the central computer (7) is connected to the bus
(5). The central computer (7) can be a common control system for the entire
power/process plant or central control system for ESP. The HVR controllers (8)
will transmit their status frames periodically over the bus (5) and all the GOTs (6)
will receive those status and update their database. User will be presented with
latest data. The pass-wise data will be passed from the GOTs (6) whenever it
requested by the central computer (7).

WE CLAIM:
1. A device for controlling and monitoring an Electrostatic precipitator (ESP)
comprising at least one of Graphical Operator Terminal (GOT) which
communicates over a Controller Area Network (CAN) in a multi-master
communication protocol with a plurality of HVR controllers (8) through an
open standard bus (5) , and operably connected to a central computer
(7), characterized in that the GOT comprises a single micro-controller (1)
and enabled to control the communication between the HVR controllers
(8) and the GOT such that all the HVR controllers (8) transmit their status
over the open standard bus (5) at a periodical interval, and GOT receives
the data and update its database for user presentation, and in that the
GOT transmitting command to any of the HVR controller (8) only when
the GOT is initiated by the user through a graphical user interface (2) and
a LCD display (4) for graphical representation of all the required
parameters
2. The device as claimed in claim 1, wherein the single micro-controller (1)
comprises a built-in memory, a time, and a CAN controller.

3. The device as claimed in claim 1, wherein the periodical interval of
communication from the HVR controllers to the GOT is within the range of
50 ms to 200 ms.
4. The device as claimed in claim 1, wherein the periodical communication
from one HVR controller is also received by the other HVR controllers.
5. The device as claimed in claim 1, comprising a LCD display device (4) for
exhibiting graphical representation of all the operating parameters.

ABSTRACT

TITLE : "A DEVICE FOR MONITORING AND CONTROLLING OF
ELECTROSTATIC PRECIPITATOR
The invention relates to a device for monitoring and controlling of electrostatic
precipitator (ESP) comprising at least one Graphical Operator Terminal (GOT)
which communicates over a Controller Area Network (CAN) in a multi-master
communication protocol with a plurality of HVR controllers (8) through an open
standard bus (5) , and operably connected to a central computer (7). The GOT
comprises a single micro-controller (1) and enabled to control the communication
between the HVR controllers (8) and the GOT such that all the HVR controllers
(8) transmit their status over the open standard bus (5) at a periodical interval,
and the GOT receives the data and update its database for user presentation and
in that the GOT transmitting command to any of the HVR controller (8) only
when the GOT is initiated y the user through a graphical user interface (2) and a
LCD display (4) for graphical representation of all the required parameters.