SCR power supplies use silicon controlled rectifier (SCR) topology to provide well-regulated voltage and current output. Silicon controlled rectifiers (SCR) are four-layer thyristors with an input control terminal, an output terminal, and a cathode or terminal that is common to both the input and output terminals. An SCR circuit is commonly used in applications that use high voltages and currents.
SCR power supplies are used to power heat induction systems that are used for heating and forging metal, melting and other heat treating applications. SCR power supplies use SCR controllers to regulate output power to industrial furnaces and ovens and are often coupled with computer hardware and software to monitor and control the power throughput. An SCR controller typically has two modes of operation: phase angle or zero-crossing. In phase angle mode, the SCR controller puts through a partial waveform during every half-wave cycle to control the power output. In zero-crossing mode, the controller detects the zero crossing of the AC voltage and allows the controller to start with a zero crossing of the voltage. A zero-crossing SCR power controller eliminates the harmonic problems often associated with the phase angle SCR controller.
The SCR controlled power supply is suitable for demanding manufacturing environments and typically comes in wide range of power levels and frequencies, depending upon the system’s power requirements. SCR power supplies range in frequency from 80 Hz to 6 kHz, and in power level from 50 kilowatts up to 3 megawatts. SCR power supplies use an AC rectifier to convert incoming AC voltage to a constant current level, providing a reliable and efficient power system for demanding process environments.
SCR power supplies use internal control and monitoring circuits to provide quick response to variations in the load. SCR power supplies can also be used to power DC motors. An SCR power controller is combined with a diode-style rectifier to operate a DC motor that is rated at 250 HP or less. A motor rated higher than 250 HP requires external DC reactors to operate.