Introduction; Overview; Description; Features - GE MM3 Instruction Manual

1 INTRODUCTION

1 INTRODUCTION 1.1 OVERVIEW
The MM3 combines control functions normally found in a low voltage motor control center (MCC) with motor
protection. This compact, microprocessor based device, provides sophisticated control and protective relaying
at significant cost savings over an MCC design using discrete devices.
Standard features simplify maintenance and plant expansion. One MM3 is required for every starter unit in the
MCC. The contactor can be energized and de-energized using the MM3's direct-wired inputs or via the serial
port. Full voltage non-reversing, full voltage Reversing, two-speed, autotransformer, inverter, wye-delta, slip
ring, and part winding type starters may be completely controlled by the MM3 using the two contactor outputs.
Motor protection is included for the most common causes of failure to prevent costly shutdowns and rewinds.
These include three-phase overload, stalled rotor, ground fault and loss of phase.
A two-wire RS485 Modbus communications port is provided for high speed communications with a complete
line-up of MCCs. Any MM3 may be interrogated on demand to determine both actual and setpoint operating
parameters. Fast response time to a request for alarm or trip status makes real time control of a complete pro-
cess possible. Statistical recording of running hours and number of starts and trips assists with predictive
maintenance scheduling.
The MM3 has been developed with economy in mind. The customer is able to choose from different options to
achieve maximum benefit from the relay when integrated into the process environment. The standard MM3
comes with three-phase overload protection (49/51), single-phase, 4 control inputs (Start, Stop, Local Isolator,
Contactor A status) plus 2 programmable inputs. The full version adds the following additional features:
nd
• 2 contactor control (wye/delta, two speed, reversing, etc.) including all timers, relays and control inputs
• Undercurrent/underpower protection (37)
• Thermistor (49) input which accepts PTC and NTC thermistor types
• Analog input/output
• 6 more programmable inputs plus 2 control inputs
Table 1–1: MM3 OPTIONS
OPTION 1 (STANDARD)
Contactor A
Serial Communications
4 Programmable Inputs
4 Control Inputs
3 Phase Inputs
1 Ground Fault Input
Aux 1 Relay
Aux 2 / ESD Relay
VT Input
GE Power Management
OPTION 2 (FULL)
Contactor A
Serial Communications
10 Programmable Inputs
6 Control Inputs
3 Phase Inputs
1 Ground Fault Input
Aux 1 Relay
Contactor B
Aux 2 / ESD Relay
VT Input
Thermistor Input
Analog Input
Analog Output
MM3 Motor Manager 3

1.1 OVERVIEW

1.1.1 DESCRIPTION

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1.1.2 FEATURES

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