FIELD OF THE INVENTION
The present invention generally relates to centralized monitoring and control of
electrostatic precipitator (ESP) used for air pollution control. More particularly,
the invention relates to a wireless communication system for communications
between microcontrollers of electrostatic precipitator and a centralized
monitoring system to control the rapping process.
BACKGROUND OF THE INVENTION
Electrostatic precipitation is one of the most effective process to control air
pollution generated by industrial emissions. This technique, which has proven
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 and paper mills and
utilities etc. The electrically charged particles are attracted towards electrode
plates, viz., discharge electrode and collection plate. ESP is divided into a
plurality of fields depending on the dust load. During continuous operation of an
electrostatic precipitator, the dust from collector plates and discharge electrodes
are periodically removed for further conveying of the collected dust. A
mechanical rapper is used to periodically dislodge the accumulated dust from the

ESP electrodes. Particulates dislodged from the plates fall into collection hoppers
at the bottom of the precipitator.
Electronic controllers associated with the Electrostatic Precipitator are used for
functions like power control and rapping motor control to optimize the dust
collection performance of the ESP. These individual controllers are interfaced to a
central monitoring and control unit to enable monitoring and control of the
physically distributed controllers from a single location.
In the prior art, mechanism exists to interface the ESP controllers to the central
monitoring and control system through wired communication. For a typical power
plant, the amount of cables required for such communication results in increased
installation cost and maintenance issues. Also, time taken to commission all
these cables is high.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a wireless communication
system for communications between ESP controllers and a centralized monitoring
and control system to control the rapping process, which eliminates the
disadvantages of prior art.

Another object of the invention is to propose a wireless communication system
for communications between ESP controllers and a centralized monitoring and
control system to control the rapping process, which eliminates communication
cables and associated commissioning and maintenance efforts between the
centralized monitoring and control system and the ESP controllers.
A still another object of the invention is to propose a wireless communication
system for communications between ESP controllers and a centralized monitoring
and control system to control in rapping process, which is equipped with external
radio frequency interfacing devices each with the ESP controllers and the
centralized monitoring and control system.
A further object of the invention is to propose a wireless communication system
for communications between ESP controllers and a centralized monitoring and
control system to control the rapping process, which is enabled to establish
reliable wireless communications to adjacent ESP control rooms without
corruption of data due to interference of the RF communication signals.
SUMMARY OF THE INVENTION
According to the invention, the microcontrollers of the ESP are linked to the
centralized monitoring and control system through a wireless communication
network. The electronic controllers each are connected to a panel-mounted

wireless interfacing device which converts the wired serial communication data to
RF medium. The RF signals transmitted over air are received by yet another RF
communication device which converts the signals back to serial communication
data and is connected to the centralized monitoring and control system.
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 a wireless interface device according to
the invention.
Figure 2 is a block diagram illustrating an ESP controller device in a
microprocessor-based control system connected to the wireless interface device
according to the invention.
Figure 3 is a block diagram illustrating a set of ESP controller devices connected
to centralized monitoring and control system according to the invention.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the block diagram of Figure 1, a wireless interface module [2] is shown. The
wireless interface module [2] is connected to the ESP controller [10] or the
central monitoring and control system [12] through a serial communication port
[4]. The central monitoring and control system [12] monitors the ESP status
and commands the ESP controllers [10] from a remote location.
The wireless interface module [2] converts RS485 serial communication packets
received from the ESP controller [10] or the central monitoring and control
system [12] to raw Radio frequency signal. The channel used by the wireless
interface module [2] for Radio frequency communication fall in the ISM band ie,
the 2.4GHz band which is available for use for industrial applications. The
interface module [2] has an antenna [1] fitted on top to achieve the signal range
required to cover the entire size of the control room that houses the ESP
controllers [10]. There are LEDs [5,6] for live indication and wireless data
transmission and reception indication. There are also LEDs [7] to receive and
transmit indication for the serial communication. The wireless interface module
[2] has a power supply connector [3] to which 24V AC power is fed. The wireless

interface module [2] uses preamble bytes to indicate the start of RF packet
transmission. Checksum logic is used to perform transmission error checks to
validate the received data.
The wireless interface module [2] is enabled to identify whether at any time, it is
connected to an ESP controller unit [10] or the central monitoring and control
system [12]. If it is connected to the ESP controller unit [10], the communication
address is identified and the communication packets meant for the unit [10]
are filtered. The interface module [2] receives the operating plant number
information from the connected unit [10 or 12], and selects accordingly the RF
communication channel to eliminate data corruption due to interference between
the RF signals in adjacent ESP control rooms.
In the block diagram shown in figure 2, the ESP controller [10] is wired to the
wireless interface module [2] using a serial communication link [8] through a
serial communication port [9] provided in the ESP controller [10].
Status of the ESP controller [10] is communicated to the wireless interface
module [2] as serial communication packets and the same is transmitted out by
the wireless interface module [2] in the form of Radio Frequency signals.
Commands from the central monitoring and control system [12] are received as
RF signals by the wireless interface module [2] and are sent to the ESP controller
over the wired serial communication line [8].

In the block diagram shown in figure 3, a set of ESP controllers [10] and
respective wireless interface modules [2] connected through serial
communication link [8] are indicated. The central monitoring and control system
[12] is also connected to a wireless interface module [13] through a serial link
[14]. This wireless interface module [13] acts as a Central Access Point as the
status and command signals for all the ESP controllers [10] in the network
converge at this point.
The wireless interface module [2] when attached to the central monitoring and
control system [12] reconfigures itself as the wireless interface module acting as
the Central Access Point [13]. The Central Access Point [13] is located in a room
[11] which houses the ESP controllers. The serial communication link [14] runs
from the Central Access Point [13] to the central monitoring and control system
[12] that is placed at a remote location.
The Central Access Point [13] including the wireless interface modules [2]
connected to the ESP controllers [10] communicate over a Radio Frequency
network [15] thus enabling wireless communication of the ESP controllers [10]
with the central monitoring and control system [12].

WE CLAIM:
1. A wireless communication system for communications between ESP
controllers and a centralized monitoring and control system to control the
rapping process, the system comprising:
• a plurality of ESP controllers having corresponding wireless interface
modules to enable the ESP controllers to communicate with the central
monitoring and control system over wireless;
• a centralized monitoring and control system capable of status
monitoring status and initiating control of the ESP controllers;
• a central access point connected to the centralized monitoring and
control system;
wherein the wireless interface modules are enabled to configure itself as
the central access point or controller wireless access point based on the
device to which it is connected.

2. The system as claimed in claim 1, wherein the wireless interface module is
enabled to identify the communication address information from the ESP
controller attached to it at any point of time, so that the communication
packets sent to the controller based on the identified communication
address is filtered.
3. The system as claimed in claim 1, wherein, the wireless interface modules
and the central access point acquire the operating plant number
information from the attached device and selects accordingly the RF
communication channel to eliminate co-channel interference between the
RF signals in adjacent ESP control rooms.
4. The system as claimed in claim 1, wherein the centralized monitoring and
control system operates through wireless communication to perform
status monitoring and user control of the ESP controllers from remote,
through logging of ESP data.

ABSTRACT
The invention relates to a wireless communication system for communications
between ESP controllers and a centralized monitoring and control system, the
system comprising a plurality of ESP controllers having corresponding wireless
interface modules to enable the ESP controllers to the central monitoring and
control system over wireless; a centralized monitoring and control system
capable of monitoring status and initiating control of the ESP controllers; a
central access point connected to the centralized monitoring and control system;
and wherein the wireless interface modules are enabled to configure itself as a
wireless interface module or the central access point based on the device to
which it is connected.