GEMotor Protection System Integrated process, control, and protection for low voltage motors

featured protection for low voltage AC motors

• Advanced automation capabilities providing customized 

protection and integrated automation control

• Cost effective solution - Low cost modular design

• Small footprint and compact design - With or without 

display, fits into standard MCC buckets

• Preconfigured logic for all standard motor starter types, 

EnerVistaTM compatible

• Integrated motor control pushbuttons

• Remote monitoring via serial communications, Modbus RTU

• Easy installation and integration - Panel mount option

• Reduced number of devices - Replaces bi-metal overload 

elements, integrates timers, relays, meters, switches, 

indicators

• Motor protection and management system for low voltage 

AC motors

• Specifically designed for Motor Control Centre applications

• Motor operational parameters and historical data

• Process data

• Phase and ground current, power, energy, voltage

• Status of relay inputs

• Trip record and pre-trip values 

• Motor statistical information

Monitoring and Metering

User Interface

Protection and Control

• Motor Thermal Model

• Single phase / Current unbalance 

• Contactor failure 

• Locked/stalled rotor 

• Ground fault 

• Undervoltage, Overvoltage

• Overtemperature

• Acceleration Trip 

• Thermistor Protection 

• Starts per Hour / Time Between Starts 

• Undercurrent and underpower

• Configurable motor start controller

• Undervoltage auto restart 

• 40 Character LCD display

• Front Panel control push buttons and programming keypad

• 11 Motor and Relay Status LED’s

• RS485 ModBus™ , 1200 - 19,200 bps

Motor Protection System

Integrated process, control, and 

protection for low voltage motors

Features

Applications

K

EnerVistaTM Software

• State of the art software for configuration and 

commissioning GE Multilin products

• Document and software archiving toolset to ensure 

reference material and device utilities are up-to-date

• EnerVistaTM Integrator providing easy integration of data 

in the MM2 into new or existing monitoring and control 

systems

Protection and Control

The MM2 is a digital motor protection 

system designed to protect and manage 

low voltage motors and driven equipment. 

It contains a full range of selectively 

enabled, self contained protection and 

control elements as detailed in the 

Functional Block Diagram and Features 

table.

Thermal Overload

An overload trip occurs when the 

thermal capacity value equals 100%. 

Thermal capacity used is calculated from 

accumulated I2t value and chosen 

overload curves. True RMS current sensing 

ensures correct response to the heating 

effect of harmonics. One of 12 different I2t 

time overcurrent overload curves may be 

selected from eight standard curves and 

four NEMA compatible curves.

Phase Unbalance

The MM2 monitors the percentage 

unbalance in the motor phase currents. If 

a phase current unbalance of greater than 

15% exists for more than five seconds an 

alarm is generated. If a phase current 

unbalance of greater than 30% exists for 

more than five seconds a single phase trip 

occurs.

Locked/Stalled Rotor

To help prevent damage to mechanical 

equipment such as pumps or fans, the 

MM2 will trip when the running current 

exceeds the stalled rotor trip level after the 

programmed time delay. This feature may 

be set to ‘OFF’ if desired, and it is disabled 

during motor starting.

Ground Fault

The ground fault level is measured as a 

percentage of the CT primary. Ground 

overcurrent can be detected either from 

the residual connection of the phase 

CTs or from a zero sequence CT. A delay 

time is set to prevent false alarms from 

momentary surges. Both a ground fault 

alarm and trip are provided. The alarm 

can be set below the trip level to provide 

an early warning of insulation breakdown.

Overtemperature

An input from motor winding thermistors 

is available. The MM2 can accept both 

positive temperature coefficient (PTC) and 

negative temperature coefficient (NTC) 

sensors. A thermistor level can be selected 

for both alarm and trip.

Cooling Time

After an overload trip, the thermal 

capacity value decreases exponentially 

to model the motor cooling characteristic. 

An overload trip can be reset when the 

thermal capacity value decreases to 15%. 

A stopped motor cooling time can be set to 

determine how long it takes for a stopped 

motor to reach steady state ambient 

temperature from its maximum allowable 

temperature.

Undercurrent/Underpower

Both undercurrent and underpower alarms 

and trips are provided with time delays. 

Protection against failed shear pin or loss 

of pump flow, which may result in only a 

small change in current, is provided by the 

underpower alarm.

Undervoltage 

For voltage sensitive loads, a drop in 

voltage increases the drawn current, 

which may cause overheating in the 

motor. The undervoltage protection 

feature can be used to either cause a trip 

or generate an alarm when the voltage 

drops below a specified voltage setting for 

a programmable time delay.

Overvoltage

An overvoltage on running motor with a 

constant load results in decreased current. 

However, iron and copper losses increase, 

causing an increase in motor temperature. 

The current overload relay will not pickup 

this condition and provide adequate 

protection. The overvoltage element may 

be used for protecting the motor in the 

event of a sustaine overvoltage condition.

Contactor Failure

The MM2 monitors the contactor while 

performing start and stop commands. If 

the contactor does not change status an 

‘open control circuit’ or ‘welded contactor’ 

alarm is triggered.

Additional Alarms

The MM2 has programmable alarms to 

warn of a number of abnormal conditions. 

These in­clude: acceleration time exceeded, 

abnormal inverter starter, in­complete start, 

motor greasing, contactor inspection, 

motor stop time, analog input, and process 

interlock switch open.

Starters 

MM2 can be programmed to serve as the 

following types of motor starters:

• Full Voltage non-reversing,

• Full Voltage reversing,

• Wye/Delta open or close transition 

starter,

• Two speed starter,

• Inverter (VSD) starter,

• Slip ring (rotor resistors) and primary 

resistance starters,

• Autotransformer open or close 

transition starter,

• Duty/Standby starter,

• Soft starter

Undervoltage Auto Restart

The motor can be automatically restarted 

after a momentary power loss when this 

feature is enabled. When the control 

voltage drops below the dropout voltage 

the contactors are de-energized. The MM2 

can initiate timers to restart selected drives 

upon the return of supply voltage. If control 

voltage is restored within the programmed 

restart time, the motor will be restarted 

immediately. If the control voltage takes 

longer to be restored, the MM2 can be 

programmed to attempt a restart after a 

programmed time delay.

Outputs 

The MM2 has one or two contactors (A 

and B) which are used for motor starting. 

There are also two auxiliary programmable 

output relays available on the MM2, 

which can be assigned to any one of 31 

functions.

Switched Inputs 

The MM2 has up to six fixed control inputs. 

These are used for start A and B, stop, local 

isolator, and contactor A and B status. The 

MM2 also has up to 10 programmable 

switch inputs. Each input can have one 

of 33 interlock functions assigned to it. A 

function can be assigned to one interlock 

input only.

Analog Input

The analog input can be scaled to user 

defined values. High and low alarm and trip 

setpoints are recorded with time delays. 

Monitoring and Metering

The MM2 offers advanced monitoring and 

metering which includes:

Metering

The MM2 meters and displays:

• current of each phase

• Ground fault leakage current

• Motor load as a % of full load current

• Thermal capacity used (%)

• % Current unbalance

• Power (kW)

• Energy (kWh)

• Voltage

• Analog input

Trip Record

When the MM2 issues a trip command a 

record is generated which includes the 

cause and pre-trip actual values.

Statistics and Maintenance

The MM2 records statistical data about 

relay and motor operation, allowing the 

user to set the interval at which routine 

maintenance tasks should be performed. 

When the times are exceeded an alarm is 

generated. These include:

• Motor greasing interval: number of 

hours between bearing lubrication

• Contactor inspection: number of starts 

after which the contactor contacts 

must be inspected for wear

• Maximum motor stopped time: the 

maximum number of hours the motor 

can be left shut down

User Interfaces

When ordered with the Panel Mount 

option, the MM2 comes equipped with a 40 

character display, LED indicators, as well 

programming and control push buttons.

Display and Keypad

The MM2 has a keypad and 40 character

display for local control and programming

without a computer. In the event of a

trip, alarm, or start block, the display will

automatically display a clear status 

message.

In addition to the programming keys, the 

panel mount option also provides 3 control 

keys for starting and stopping the motor 

locally. 

Indicator LEDs

The panel mount MM2 has nine LED’s that 

provide the status of the motor and relay 

output contacts. Two additional LED’s 

indicate whether the relay is in Auto or 

Manual control mode.

Communications

The MM2 uses a ModBus® RTU RS485 

connection for communication. Up to 32 

MM2s can be daisy-chained together on a 

single communication channel. The MM2 

supports a number of baud rates, ranging 

from at 1200 to 19,200 bps. A RS232/485 

converter module may be used to connect 

a personal computer to the MM2.

Software

The MM2 comes with a Windows®-based 

configuration program called MM2PC. It 

allows access to all the features of the 

MM2 with easy to use, pull-down menus. 

Using this program it is possible to:

• Program or modify setpoints

• Load or save setpoints from or to a 

disk

• Read actual values from the MM2

• Monitor status

• Read pre-trip data and trip record

• Display dynamic trending of actual values

• Get help on any topic

• Print the instruction manual from disk

Mounting Configurations

The MM2 can be ordered as either a chassis 

mount or panel mount relay.

The chassis mount comes with all of the 

standard features and may be ordered 

with one or both of the option packages. 

Setpoints are loaded through the RS485 

port using the MM2 PC Setup program.

The panel The MM2 Panel Mount (PD) 

option is available when both of the option 

packages have been ordered. The panel 

mount MM2 is mounted through the front 

panel of the MCC, providing complete local 

programming and control.

Option Packages

Option package 1 increases the control and 

diagnostic features available. It includes:

• Process control and process inputs

• Undervoltage auto restart

• Enhanced diagnostics including alarms, 

pre-trip data, and historical statistics 

about the use and performance of the 

motor and drive

Option package 2 increases the protection 

features and input options. It includes:

• Second contactor control, including two 

more control inputs

• Single-phase VT input used to calculate 

and display the kW and kWh absorbed 

by the drive

• Enhanced protection including five 

more protection features

• Motor winding thermistor input

EnerVistaTM Software

The EnerVista™ Suite is an industry 

leading set of software programs that will 

simplify every aspect of using the MM2 

relay. Tools to monitor the status of your 

motor, maintain your relay, and integrate 

information measured by the MM2 into 

HMI or SCADA monitoring systems are 

available. 

EnerVistaTM Launchpad

EnerVista™ Launchpad is a powerful 

software package that provides users with 

all of the setup and support tools needed 

for configuring and maintaining GE Multilin 

products. Launchpad allows configuring 

devices in real-time by communicating 

using serial, Ethernet , or modem 

connections, or offline by creating setting 

files to be sent to devices at a later time.

Included in Launchpad is a document 

archiving and management system 

that ensures critical documentation is 

up-to-date and available when needed. 

Documents made available include:

• Manuals

• Application Notes

• Guideform Specifications

• Brochures

• Wiring Diagrams

• FAQ’s

• Service Bulletins

Viewpoint Monitoring

Viewpoint Monitoring is a powerful yet 

simple-to-use monitoring and data 

recording package for small systems. 

Viewpoint Monitoring provides a 

complete HMI package with the following 

functionality