Three-Phase SSR for Heater Control
The Omron G3PE-525B-3N is a three-phase solid state contactor purpose-built for resistive heater loads, rated 25 A at 200 to 480 VAC. It switches three-phase heater banks — ovens, furnaces, extruder barrel heaters — where mechanical contactor wear from frequent cycling is a problem. The 12 to 24 VDC input lets a PLC or temperature controller drive it directly, no interposing relay needed. Zero-cross switching turns the load on at the voltage zero point, which cuts the inrush current spike that shortens heater life and flickers the line. For a 25 A heater bank running at 480 VAC, that matters — the triac sees a clean turn-on, not a current surge.
Operating temperature range of -30 to 80°C covers most industrial enclosures, including unventilated cabinets near a kiln or oven. Storage down to -30°C is fine for unheated warehouses — no special cold-weather handling needed.
Electrical Characteristics
Leakage current is 20 mA max at 480 VAC — negligible for a resistive heater load, but worth noting if the circuit has a sensitive ground-fault monitor. Output ON voltage drop is 1.8 V RMS max, which means about 4.5 W of dissipation per pole at 25 A — the heatsink handles that, but don't bury it against other heat sources. Dielectric strength of 2,500 VAC for 1 minute between input/output and case gives solid isolation for the control circuit. Insulation resistance is 100 MΩ min at 500 VDC. The phototriac coupler provides the optical isolation between the 12-24 VDC control side and the power side. Operate and release times are both 1/2 of load power source cycle plus 1 ms max — at 50 Hz that's about 11 ms, at 60 Hz about 9.3 ms. Fast enough for closed-loop temperature control, but not for synchronous switching applications.