FIELD OF INVENTION
The invention in general relates to an Electrostatic Precipitator (ESP) used typically in a coal fired thermal power stations or industrial applications to collect the particulate matter from the flue gas before letting through chimney to avoid environmental pollution.
The invention in particular relates to a signal conditioning system which measures the current density of the ESP Model having different emitting electrodes to study the influence of Emitting Electrode geometries on current distribution in ESP.
BACKGROUND OF THE INVENTION
Electrostatic precipitator is predominantly used for suspended particle collection in flue gas, where the dust content is in excess. 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 positive and negative ion. Under the action of the electric field the charged dust particle moves to oppositely charged electrode plates, viz., emitting electrode and collecting electrode and eventually gets adsorbed, thus achieving dust-collecting effect. Efficiency of dust collection in ESP is influenced by how homogenously the current is distributed in the collecting plate. This is decided by the shape and arrangement of emitting electrodes with respect to collecting electrode.
Inefficiency of the existing ESP electrode geometry and arrangement in providing homogenous current distribution leads to lumping of current and hence dust to some areas of the electrode resulting in excess sparking and occurrence of back corona. Some areas may be deprived of any current and hence no dust collection will occur there. All these will decrease the collection efficiency of ESP.

So it is important to measure the current distribution pattern in the ESP collecting plate for different emitting electrode geometries for selecting the optimum configuration. A signal conditioning system is developed to measure the current density in the ESP test bed, which tells whether the current is distributed homogeneously or looped, which in turn tells the operator the current is not distributed homogeneously to a particular cross section, particle charging is affected and hence the collection efficiency.
OBJECTS OF THE INVENTION
An object of the invention is to measure the current distribution in the ESP model.
Another object of the invention is to understand the influence of Emitting Electrode geometry on current distribution in collecting electrode.
Yet another object of the invention is to condition the signal and make it in a readable form and send the data to the logging system.
SUMMARY OF THE INVENTION
The current is distributed in different patterns in the ESP test bed, which varies with different Emitting Electrode configurations, which affects the particle charging. The particle charging depends strongly on how equally the current is distributed in a particular cross section. The uneven distribution of current will accumulate charged particles on a single spot where the density of current will be more which forms a thick layer of dust particle and promotes back corona. Above all, if the distribution is not equal, all particles will not get charged, some will escape and contribute in environmental pollution.

A signal conditioning system is developed to measure the current density in the ESP test bed, which tells whether the current is distributed homogeneously or looped, which in turn tells us if the current is not distributed homogeneously to a particular cross section, particle charging is affected and hence the collection efficiency of the ESP.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure [1] shows a block diagram of the Signal Conditioning System used to Measure the Current density in an ESP model in accordance to the invention.
Figure [2] shows an internal circuit diagram of the Signal Conditioning System representing a single pair of blocks (6) and (7) in accordance to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The single field ESP Test bed consists of a moving Collecting Electrode (2) and a Static Emitting Electrode (3), the Emitting Electrode (3) which is connected to a negative DC potential and the Collecting Electrode (2) which is connected to the ground. When a negative DC is applied to the Emitting Electrode (3) an Electric field is generated between Emitting electrode (3) and Collecting Electrode (2) which ionizes the air around it, and the particles moving through it gets negatively charged and attracted towards the collecting electrode (2).
The current distribution is captured by moving the Collecting Electrode (2) towards left and right across the axis of emitting electrode (3), In helical Emitting electrode, the Collecting Electrode (2) will be moved left and right for one helical pattern (one cycle) of the Emitting electrode.

Coaxial signal cables (4) are connected to Collecting Electrode (2) symmetrically in the centre across the breadth, which carries the current signal from a unit area on the Collecting Electrode surface (2) to the signal Conditioning System module (1).
Each Signal Conditioning System module (1) consists of five high impedance inputs (6), the signal (nano ampere range) captured is passed through this high impedance input (6) and then passed through a unity gain amplifier (7), which is then passed on to the data acquisition system (5) to capture and study the current distribution pattern and effect on particle charging.
Each Signal Conditioning System Module (1) is Zero offset tuned first. In this Tuning, the SPDT switch is kept at the ground position at input side, the potentiometer shall be adjusted such a way so that exactly 0 Volt appear at the output side. The voltage measurement at the output end shall neither go to negative side nor to the positive side. After that as the circuit is a unity gain (7), applying 0.5 volt at the input side on position of SPDT switch, compensating the voltage drop at the voltage divider circuit, around 0.34 volt should appear at the output end, ensuring zero offset during ground position of SPDT switch.

WE CLAIM:
1. A Signal Conditioning system for measuring current density in an electrostatic Precipitator (ESP) that comprises
- a Signal Conditioning Module (SCM) (1) that comprises plurality of impedance (6) coupled to a unity gain amplifier (7);
- an electrostatic test bed of a movable collecting electrode (CE) (2) and a Static Emitting Electrode (3), where negative direct current (DC) is applied to the Emitting Electrode (3) and an electric field is generated that ionizes the surrounding air and initiates rotation of the CE (2) in a pattern;
- coaxial cable (4) coupled to the CE (2) to allow passage of negative current to the said SCM (1) wherein the output of the SCM (1) is fed to a data acquisition system (5).

2. The signal conditioning system as claimed in claim 1, wherein the movable collecting electrode (CE) (2) moves in a helical pattern.
3. The signal conditioning system as claimed in claim 1, wherein the air ionized around the Collecting Electrode (2) is negatively charged and tends to push towards the Collecting Electrode (2).
4. The signal conditioning system as claimed in claim 1, as illustrated in the accompanying drawings.