© 2016 Littelfuse Protection Relays & Controls
Protection Relays
Voltage Monitoring Relays
www.littelfuse.com/355
Rev: 1-A-062716
Description
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 10A general purpose
SPDT relay. The 355400 and 355600 are equipped with a 470VA
@ 600VAC pilot duty SPDT relay. A high voltage (600V) DPDT
relay output option is available with the 400V model.
Features & Benefits
FEATURES BENEFITS
Proprietary
microcontroller
based circuitry
Constantly monitors 3 phase voltage to protect
against harmful line conditions, even before the
motor is started
Advanced LED indication
Provides diagnostics which can be used for
troubleshooting and to determine relay status
Adjustable trip and
restart delay settings
Prevent nuisance tripping due to rapidly fluctuating
power line conditions and allows staggered start up
of multiple motors, after a fault, to prevent a low
voltage condition
Combines protection
and diagnostics
Perfect for heavy duty applications: pump panels,
commercial HVAC, and oil rigs
600V rated relay
contacts available
on some models
Eliminates the need for a control transformer to step
voltage down to 120 - 240V for a control circuit
3-phase voltage/phase monitor
355 SERIES
Wiring Diagram
TYPICAL WIRING DIAGRAM FOR MODEL 355 WITH ALARM CONTROL
TYPICAL WIRING DIAGRAM FOR MODEL 355 WITH MOTOR CONTROL
Ordering Information
MODEL LINE VOTAGE DESCRIPTION
355200 190-240VAC SPDT
355400 380-480VAC SPDT
3554005 380-480VAC DPDT
355600 475-600VAC SPDT
