1 of 3
Littelfuse.com/MPS
©2022 Littelfuse, Inc.
Specications are subject to change without notice.
Revised: 10/19/2022
Motor and Pump Protection Relays
MPS Series
Description
The MPS Motor Protection System monitors voltage, current, and temperature to provide a comprehensive package of 22
protective functions. The MPS is a modular system with integrated protection, motor control, metering, and data-logging
functions. This system is typically used to provide protection for three-phase low- and medium-voltage, medium- to high-
horsepower induction motors.
2
Control Unit (MPS-CTU)
• Current inputs—5-A or 1-A secondary phase current transformers
• Voltage inputs—up to 600 V without PTs
• Earth-leakage input—5-A or 1-A secondary or sensitive transformer
• Tachometer (high-speed pulse) input
• 8 digital inputs, 5 relay outputs, 1 analog input and output
• 24-Vdc supply for OPI and RTD modules, and for digital inputs
• IRIG-B time-code input
• ½ DIN size, surface mount
• RS-485 network communications (Standard)
• DeviceNet
™
, Profibus
®
, or Ethernet communications available
1
Operator Interface (MPS-OPI)
• Large, bright, 4 x 20 vacuum-fluorescent
display
• Display metered values
• Access set points
• Powered by Control Unit
• Panel mount or attach directly to Control Unit
• Remote mounting (1.2 km or 4000 ft
maximum loop length)
• ½ DIN size
• Hazardous-location certified
Features & Benets
FEATURES IEEE # BENEFITS
Overload
49, 51
Extends motor life and prevents insulation failures and fires
Current unbalance/Phase loss/Phase
reverse
46
Prevents overheating and extends motor life
Overcurrent/Jam
50, 51
Prevents catastrophic failures and fires and extends motor life
Ground fault
37
Detects low-level or no-load conditions
RTD temperature
50G/N, 51G/N
Prevents catastrophic failures and fires
Overvoltage
38, 49
Optional RTD temperature protection (MPS-RTD module) for high ambient
or loss of ventilation protection
Undervoltage
59
Prevents stress to insulation
Voltage unbalance
27
Prevents a start attempt when it will damage the motor
Phase differential
47
Detects unhealthy supply voltage
Dynamic thermal model
87
Provides sensitive protection for high-resistance winding faults
Reduced overcurrent model Provides protection through starting, running, overload, and cooling cycles
Starter control Minimizes arc-flash hazards during maintenance
Motor Protection System
1
2
2 of 3
Littelfuse.com/MPS
©2022 Littelfuse, Inc.
Specications are subject to change without notice.
Revised: 10/19/2022
Motor and Pump Protection Relays
MPS Series
Applications
• Motor protection
Specications
Protective Functions
(IEEE Device Numbers) Overload (49, 51), Phase reverse (current) (46), Overfrequency (81), Overcurrent (50, 51), Jam,
Underfrequency (81), Ground fault (50G/N, 51G/N), Undercurrent (37), Unbalance (voltage) (47),
Failure to accelerate, RTD temperature (38, 49), Unbalance (current) (46), Underspeed (14),
Starts per hour (66), Phase loss (voltage) (47), Overvoltage (59), Differential (87), Phase loss
(current) (46), Undervoltage (27), Phase reverse (voltage) (47), Power factor (55)
Input Voltage 65-265 Vac, 25 VA; 80-275 Vdc, 25 W
Power-Up Time 800 ms at 120 Vac
Ride-Through Time 100 ms minimum
24-Vdc Source 100 mA maximum
AC Measurements True RMS and DFT, Peak, 16 samples/cycle, and positive and negative sequence of fundamental
Frequency 50, 60 Hz or ASD
Inputs Phase current, Earth-leakage current, Phase voltage, 7 digital, tachometer, 1 analog
Output Contacts 5 contacts — See Product Manual
Communications Allen-Bradley
®
DFI and Modbus
®
RTU (Standard); DeviceNet
™
, Ethernet (Optional)
Conformally Coated Standard feature
Warranty 10 years
Control Unit Mounting Surface
Operator Interface Mounting Panel, Control-Unit mounted
Certication & Compliance
CSA
CSA Certified
(CSA C22.2 No. 14, CSA C22.2 No. 213-M1987 (OPI and
RTD modules only), CSA E60079-15:02 (RTD module only))
RCM RCM
UL
UL Recognized
(UL 60947-4-1, UL 1053, UL 60079-15 (RTD module only))
Accessories
A
Phase Current Transformers
Phase CTs are required to detect phase currents.
B
Ground-Fault Current Transformer
Required zero-sequence current transformer detects ground-fault current. Available with 5-A and 30-A primary ratings for
low-level pickup.
C
MPS-RTD Temperature Input Module
Optional module provides 8 inputs to connect Pt100, Ni100, Ni120, and Cu10 RTDs.
Ordering Information
ORDERING NUMBER COMMUNICATIONS
MPS-CTU-01-00 RS-485
MPS-CTU-02-00 RS-485 & DeviceNet
™
MPS-CTU-04-00 RS-485 & EtherNet/IP
™
& Modbus
®
TCP