GE Power Management
MM2 Motor Manager 2 9-33
9 STARTER TYPES 9.11 WYE-DELTA CLOSED TRANSITION STARTER
9
The CHANGE OVER TIME setpoint appears only if the Wye Delta starter type has been selected. See
the CHANGE OVER CURRENT setpoint description above for operation.
9.11.2 MM2 SEQUENCE
START sequence:
1. Start command received by the MM2.
2. Close Contactor A relay – this causes the 1S wye contactor to pick up which connects the motor
windings in the wye configuration.
3. Wait approximately 20 ms.
4. Close AUX Relay 1 – this causes the 1M main contactor to pick up which starts the motor.
5. Maintain 1S and 1M contactors until CHANGE OVER CURRENT or CHANGE OVER TIME initiates a tran-
sition from wye to delta. See CHANGE OVER CURRENT and CHANGE OVER TIME descriptions above
for more detail.
6. Close Contactor B relay – this causes the 2S resistor contactor to pick up which connects the
resistors across the line.
7. Wait approximately 20 ms.
8. Open Contactor A output relay. This causes the 1S wye contactor to drop out. The normally
closed auxiliary contacts on the 1S wye contactor pick up the 2M delta contactor which connects
the motor in the delta configuration. The normally closed auxiliary contacts on the 2M contactor
drop out the 2S resistor contactor.
STOP/TRIP sequence:
1. Stop command received by the MM2 or a trip occurs.
2. Open 1M and 2M contactors.
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 by the Contactor A Status N.O., Contactor B Status N.O. or the WYE
DELTA 1M CONTACT inputs within one second of closing the corresponding output relay, an OPEN
CONTROL CIRCUIT alarm will occur. This will open all three output relays which will stop the motor.
If feedback remains at the programmable switch input that has been configured to WYE DELTA 2S
CONTACT for more than one second, a WELDED CONTACTOR alarm will occur. This will open all
three output relays which will stop the motor. This will prevent the resistors from burning out if the 2S
contactor does not open after switching to the delta configuration.
If feedback remains at Contactor A Status N.O., Contactor B Status N.O. or WYE DELTA 1M CON-
TACT inputs for more than one second after opening the corresponding output relay, a WELDED
CONTACTOR alarm will occur.
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