Voltage control system for electrostatic oil treater

In an electrostatic separation process, an automatic voltage control system for coalescing a first fluid which is dispersed throughtout a second fluid by controlling the voltage applied to the primary winding of the step-up transformer, the secondary winding thereof energizes the grid of the electrostatic separation process, comprising:

• (a) the step-up transformer having a primary winding and a secondary winding with the primary winding connected to an alternating current voltage source and the secondary winding connected across the grid of the electrostatic separator;
• (b) means for measuring the current passing through the primary winding of the step-up transformer;
• (c) means for measuring the voltage across the primary winding of the step-up transformer;
• (d) a solid state switch in series with the primary winding of the transformer;
• (e) means responsive to the current measured by the current measuring means and responsive to the voltage measured by the voltage measuring means for detecting an arcing condition;
• (f) means for comparing the current passing through the primary winding as measured by the current measuring means to a predetermined first primary current limit set point, the comparing means having a first input port for receiving the measured primary current from the primary current measuring means, a second input port for receiving the first primary current limit set point and an output port at which the compared current signal is presented;
• (g) voltage control circuit means responsive to the compared current signal and responsive to the voltage measured by the voltage measuring means for generating a first control signal to switch the solid state switch on to control the magnitude of the voltage applied to the primary winding of the step-up transformer;
• (h) voltage control circuit means for generating a periodic second control signal to switch the solid state switch on to control the magnitude of the voltage applied to the primary winding of the step-up transformer;
• (i) circuit means for limiting the magnitude of the first control signal by the magnitude of the second control signal producing a magnitude controlled triggering signal;
• and
• (j) circuit means for applying the magnitude controlled triggering signal to trigger the solid state switch, whereby the voltage applied to the grid and in turn the electric field intensity between grid elements increases then decreases periodically and within the limit of the periodically increasing then decreasing voltage the automatic voltage control system reduces the voltage applied to the grid to zero temporarily upon detecting an arcing condition or a primary current limit has been reached.