The 355 series is a 3-phase voltage monitor with adjustable trip and restart delay, adjustable voltage unbalance and multiple diagnostic lights. It is perfect for heavy duty applications that need both protection and simple user-friendly diagnostics. Applications include pump panels, commercial HVAC, oil rigs and others. The 355 series uses microcontroller technology to monitor incoming voltage and de-energize its output relay if power problems exist. The 355 series can protect motors from damage caused by single-phasing, high and low voltage, phase reversal and voltage unbalance. It has four diagnostic LEDs that clearly show overvoltage, undervoltage, voltage unbalance, reverse phase and normal conditions. The 355200 is equipped with a heavy duty 10 A general purpose SPDT relay. The 355400 and 355600 are equipped with a 470 VA at 600 VAC pilot duty SPDT relay. A high voltage (600 V) DPDT relay output option is available with the 400V model.