The 350 series is a heavy duty voltage monitor. This product should be used when high current relays or dual contacts are required or 480 VAC controls are used. Since the 350 series uses heavy duty relays, it comes in fixed voltage range models rather than a dual auto-ranging version like the model 250. The 350200 has a 15 A general purpose contact. The 350400 provides a SPDT (Form C) relay rated to switch up to 600 VAC, allowing the use of 480 VAC controls, eliminating the need for a control power transformer to step the voltage down to 120 to 240 VAC. The 350 microcontroller based family of products are low cost yet highly advanced solutions to heavy duty problems. The 350 includes advanced single LED diagnostics. Five different light patterns distinguish faults and normal operating conditions.