In summary, Crydom’s PMP series of proportional control relays is designed with microcontroller based technology to provide precise control of the power delivered to a single-phase load, with ratings up to 90A at 90 to 600 V_AC. These solid state relays can control the load power in proportion to an analog control input, which can be a DC voltage (0-5 or 0-10V) or a DC current (4-20 mA); as this control input varies from 0 to 100%, so does the output of the SSR. The use of an auxiliary DC power supply allows this series to have good precision and low noise sensitivity over the full control voltage range. The output of the SSR can be controlled by two different methods: Phase Angle control, which works by varying the firing angle of the SCRs, and Burst Fire control (with Distributive Zero Cross), which is a time proportioning method in which full AC cycles are conducted at the output. The PMP series proportional controllers are ideal for a wide range of applications that require control of the load power, such as lamp dimming and resistive heating control.