Protection Relays
Voltage Monitoring Relays
355 SERIES
3-phase voltage/phase monitor
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.
Wiring Diagram
TYPICAL WIRING DIAGRAM FOR MODEL 355 WITH MOTOR CONTROL
Features & Benefits
FEATURES
Proprietary
microcontroller
based circuitry
Advanced LED indication
Adjustable trip and
restart delay settings
Combines protection
and diagnostics
600V rated relay
contacts available
on some models
BENEFITS
Constantly monitors 3 phase voltage to protect
against harmful line conditions, even before the
motor is started
Provides diagnostics which can be used for
troubleshooting and to determine relay status
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
Perfect for heavy duty applications: pump panels,
commercial HVAC, and oil rigs
Eliminates the need for a control transformer to step
voltage down to 120 - 240V for a control circuit
TYPICAL WIRING DIAGRAM FOR MODEL 355 WITH ALARM CONTROL
Ordering Information
MODEL
LINE VOTAGE
DESCRIPTION
355200
355400
3554005
355600
190-240VAC
380-480VAC
380-480VAC
475-600VAC
SPDT
SPDT
DPDT
SPDT
© 2016 Littelfuse Protection Relays & Controls
www.littelfuse.com/355
Rev: 1-A-062716
Protection Relays
Voltage Monitoring Relays
355 SERIES
Specifications
Input Characteristics
Line Voltage
355200
355400
355600
(Specify voltage range)
Frequency
Functional Characteristics
Low Voltage (% of setpoint)
Trip
Reset
High Voltage (% of setpoint)
Trip
Reset
Voltage Unbalance (NEMA)
Trip
Reset
Trip Delay Time:
Low & High Voltage
and Unbalance
Single-phasing Faults
(>25% UB)
Restart Delay Time
After a Fault or Power Loss
Output Characteristics
Output Contact Rating
SPDT (355200)
Pilot Duty
General Purpose
SPDT (355400, 355600)
Pilot Duty
DPDT (-5 Option)
Pilot Duty
190-240VAC
380-480VAC
475-600VAC
50*/60Hz
90% ±1%
93% ±1%
110% ±1%
107% ±1%
2-8% adjustable
Trip setting minus 1%
General Characteristics
Temperature Range
Operating
Storage
Repeat Accuracy
Fixed Conditions
Maximum Input Power
Terminal
Torque
Wire Size
Transient Protection
(Internal)
Safety Marks
UL
Dimensions
Weight
Mounting Method
Special Options
Option 5 - DPDT Relay
-40° to 70°C (-40° to 158°F)
-40° to 80°C (-40° to 176°F)
±0.1%
6W
7 in.-lbs.
12-18AWG
2500V for 10 ms
UL508 (File #E68520)
H
74.42 mm (2.93”);
W
133.86 mm (5.27”);
D
74.93 mm (2.95”)
0.94 lb. (15.04 oz., 426.38 g)
#8 screws
2-30 seconds adjustable
2 seconds
Manual, 2-300 seconds adj.
*Note: 50Hz will increase all delay times by 20%.
480VA at 240VAC
10A
470VA @ 600VAC
470VA @ 600VAC
© 2016 Littelfuse Protection Relays & Controls
www.littelfuse.com/355
Rev: 1-A-062716
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