355600 - 355 Series

Series: 355 Questions? Contact Littelfuse Support
Littelfuse Voltage Monitoring Relays
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The 355 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 uses microcontroller technology to monitor incoming voltage and de-energize its output relay if power problems exist. The 355 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 355-200 is equipped with a heavy-duty 10A general purpose SPDT relay. The 355-400 and 355-600 are equipped with a 470VA @ 600VAC pilot duty SPDT relay. A high voltage (600V) DPDT relay output option is available with the 400V model.

Property (Mouseover for details) Value
Input Voltage (V) 475 to 600VAC
Maximum Input Power 6W
Input AC Line Frequency (Hz) 50/60Hz (50Hz will increase all delay timers by 20%.)
Output Form SPDT
Output Load Rating (VA) Pilot Duty: 470VA @ 600VAC; General Purpose: 10A
Restart Delay Range After a Fault or power loss: Manual 2 - 300s adjustable
Repeat Accuracy (%) ±0.1%
Trip Delay Range Under/Over Voltage and Unbalance: 2 - 30s adjustable; Single-phasing Faults (>25%UB): 2s
Trip Point Accuracy (%) ±1%
Overvoltage Trip Voltage (%) 110%
Overvoltage Reset Voltage (%) 107%
Undervoltage Trip Voltage 90%
Undervoltage Reset Voltage (%) 93%
Voltage Unbalance Trip Point (%) 2-8% adjustable
Voltage Unbalance Reset (%) Trip setting minus 1%
Termination Type Torque: 7in-lbs; Wire Size: 12-18AWG
Mounting Method #8 screws
Operating Temperature -40° to 70°C (-40° to 158°F)
Storage Temperature (F/C) -40° to 80°C (-40° to 176°F)
Dimensions 2.93 in H x 5.27 in W x 2.95 in D (74.4 x 133.9 x 74.9 mm)
Weight (lbs/g) 0.94 lb. (15.0 oz. 426.4 g)