3021A Three Phase Power Controller

The model 3021A is a two-leg Zero-Cross SCR power controller that linearly controls, proportional to 0-5 VDC or 0-10 VDC or potentiometer command signal, the power applied to a three phase electrical load. The controller is available with current ratings from 10 to 70A and voltage ratings from 120 to 575 VAC.

The controller consists of a master and a slave assembly. Each assembly consists of a heatsink and an SCR (Silicon Controlled Rectifier) module containing two SCRs configured to operate as a Zero-Cross AC switch. The SCR module also provides electrical isolation between the line and load voltage and the heatsink and the input command to the SCR module.

An electronic circuit on the master assembly controls the ON/OFF switching of the SCR module causing the load power to be directly proportional to the command signal. The fast ON/OFF Zero-Cross switching improves heater life and provides superior performance over that achieved by relays, contactors or other solid state time proportional controls. The 3021A has proven to be an economical and very compact power control solution for industrial applications requiring high reliability and long life.

Some features include:

• Line voltage compensation holds load voltage constant with changes in line voltage
• Compact and economical
• Fast cycling distributive control improves heater life and reduces temperature variations.
• 2500 VAC RMS isolation between input/output and line voltage/heatsink.
• Natural convection.