mprMIMPR 6/3 Digital Motor Protection Relay

new generation of microprocessor based relay designed to protectthree phase induction motors. Featuring Directional Ground Fault and

true RMS line currents are measured at a sampling rate of 0.5 mSec. The MPR-6 includes three temperature (RTD's or Thermistors) inputs, all combined to provide a comprehensive protection package.

The MPR-6 incorporates two main functions:

  1. Advanced, state of the art motor protection.
  2. Real time supervision and communication.

Advantages at glance

  • Directional Ground Fault - New for 2003.
  • Comprehensive package, 26 protective functions
  • Ability to select each protective functions as Alarm, Trip, both or none.
  • True RMS at a scan time of 0.5 mSec
  • Full control and supervision through RS 485 with open Modbus protocol.
  • Compact, simple to install and easy to operate.


  • Too many starts
  • Maximum start time
  • Under current
  • Load increase
  • Thermal level (Overload)
  • Over-current Jam
  • Over-current Stall
  • Over-current Short circuit
  • Unbalanced current
  • Ground fault current
  • Over-temp. -RTD or PTC/NTC


  • External faults 1&2 - N.O / N.C contacts
  • Current fluctuation (Broken Bar Detection)
  • Analog Output

Configurable Operation

Any fault can be designated as an Alarm, Trip, both or none. Furthermore, two auxiliary

relays can be specified to operate with any of the faults.

"Time To Trip" and "Time To Start"

When current exceeds the overload setting, a unique built-in algorithm calculates the time

until the motor will be tripped (when thermal capacity is 100%), enabling the operator or host

computer to take corrective action before tripping. After the MPR-6 has tripped the motor, it

will calculate the time delay until the motor can be restarted, after cooling down.

Informative Data

An illuminated LCD provides clear status and statistical information.

Actual Data

Phase currents

Ground fault current

Thermistor resistance

Motor load in % of FLC

Thermal capacity

Time to trip

Time to start

Unbalanced current

Statistical Data

Motor run time

Total number of starts

Total number of trips

Last start time

Last start peak current

Last trip

Last alarm

Phase currents

Ground fault current

All at trip time


RS485 serial link with MODBUS RTU communication protocol, operating at baud rate of

1200 to 9600 bits/sec, enables monitoring of set points and actual parameters.

Up to 32 MPR-6 relays can be connected to the host computer on the same twisted shielded pair.

Typical applications

Small to medium size low and medium voltage motors.

Motors in the Process Industry

Critical motors requiring special protection or supervision.