The ACVC100 is an analog SCR (silicon-controlled rectifier) power controller from Backer Hotwatt Inc. — a specialist in electric heating elements and their associated control components. Unlike simple electromechanical contactors that cycle heater power fully ON or fully OFF, the ACVC100 uses phase-angle firing to deliver continuously variable AC voltage to resistive heater loads. By triggering the SCR at a controlled point within each AC half-cycle, the controller adjusts the proportion of the sine wave delivered to the load — from 0% to near 100% — with the smoothness of an analog dimmer rather than the abrupt steps of a time-proportioned relay.

Why use phase-angle control instead of zero-cross or on-off switching?

Phase-angle control provides three advantages for precision heating applications. First, it eliminates the thermal cycling amplitude inherent in on-off control — critical for processes where temperature overshoot and undershoot degrade product quality, such as laboratory oven drying and plastic thermoforming. Second, the continuously variable output enables tight closed-loop temperature regulation when paired with an external PID controller providing a 4–20 mA or 0–10 VDC command signal. Third, because switching occurs at every half-cycle rather than every few seconds, the load current drawn from the supply is essentially continuous — avoiding the flicker and harmonic burst issues that on-off cycling at multi-second periods can impose on the facility power distribution. The surface-mount bracket design allows direct attachment to equipment chassis or back panels for OEM integration.