This controller is designed for resistive heating applications. Both the 902 and 903 Series three phase SCR controllers are designed to function as a master/slave system. The 902 has two triacs and the 903 has three triacs, which may be connected in the line or in the Delta or Wye respectively.

A master unit is required for each control input. A master unit includes a 901-D Multiple Input Logic card mounted on the master for driving the power switch section of the 902/903. Additional three phase circuits that are controlled by the same input can be connected to a slave 902/903 unit.

Each three phase Master or Slave requires a separate three phase circuit connected to its specific KW load. Slave controllers used "stand alone" without a Master controller function as a "zero firing" three phase solid state contactor.

Slave units are identified with an “S” suffix: 902-S and 903-S. Model numbers also include voltage and current ratings of units.