GE Power Management
MM2 Motor Manager 2 9-15
9 STARTER TYPES 9.5 PRIMARY RESISTANCE STARTER
9
9.5.2 MM2 SEQUENCE
START sequence:
1. Start command received by the MM2 (serial, switch input or faceplate).
2. Close and maintain Contactor A relay – the motor is now starting at reduced voltage
3. Wait STAGE ONE SHORTING TIME delay.
4. Close and maintain Contactor B relay – the motor is now running at full voltage.
STOP/TRIP sequence:
1. Stop command received by the MM2 or a trip occurs.
2. Open Contactor A and B output relays.
The slip ring starter type can be used for the PRIMARY RESISTANCE STARTER type since it has
the same logic as the slip ring starter.
When the power to the MM2 is interrupted, all output relays on the MM2 will de-energize causing
them to open and stop the motor. The MM2 can only be wired for fail-safe operation.
If feedback is not received from the S or R contacts to the Contactor A or B Status N.O. inputs within
one second of closing Contactor A or B output relays, an OPEN CONTROL CIRCUIT alarm will
occur. This will cause Contactor A and B output relays to open. If feedback remains at the Contactor
A or B Status N.O. input more than one second after opening the Contactor A or B output relays, a
WELDED CONTACTOR alarm will occur.
A separate voltage transformer must be used for the VT input to accurately measure the voltage at
the motor. See Figure 9–12: PRIMARY RESISTANCE STARTER on page 9–16.
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