GE Power Management
MM2 Motor Manager 2 9-21
9 STARTER TYPES 9.7 AUTOTRANSFORMER OPEN TRANSITION STARTER
9
S3 PROCESS\PROGRAMMABLE INPUTS\INTERLOCK INPUT 10: AUTOTRANS 2S CONTACT
S4 CONTROL\AUX 1 RELAY CONFIG\AUX RELAY 1 FUNCTION: AUTOTRANSFORMER 2S
The CONTACTOR SEQUENCE setpoint appears when STARTER TYPE is selected as AUTOTRANS OPN
TRANS. The 1S-2S value closes the 1S contactor ahead of the 2S contactor as per some manufac-
turer’s wiring practices. The 2S-1S value closes the 2S contactor ahead of the 1S contactor, another
common wiring practice.
The CHANGE OVER TIME setpoint appears when STARTER TYPE is selected as AUTOTRANS OPN TRANS.
This represents the time delay from the closure of Contactor A until the opening of Contactor A.
The STARTS PER HOUR setpoint appears only when STARTER TYPE is selected as AUTOTRANS OPN
TRANS. This setpoint limits the number of starts per hour to prevent overheating of the autotrans-
former windings.
9.7.2 MM2 SEQUENCES
START (CONTACTOR SEQUENCE set to 1S-2S) sequence:
1. Start command received by the MM2 (serial, switch input or faceplate).
2. Close and maintain Contactor A output relay – close 1S contactor.
3. Wait 20 ms, close and maintain Aux. 1 output relay – power is applied to the autotransformer.
4. Wait for the time set in the CHANGE OVER TIME setpoint.
5. Open Contactor A and Aux. output relays.
6. Wait 20 ms.
7. Close and maintain Contactor B output relay.
START (CONTACTOR SEQUENCE set to 2S-1S) sequence:
1. Start command received by the MM2 (serial, switch input or faceplate).
2. Close and maintain Aux. 1 output relay – power is applied to the autotransformer.
3. Wait 20 ms, close and maintain Contactor A output relay – close the 1S contactor.
4. Wait for the time set in the CHANGE OVER TIME setpoint.
5. Open Contactor A and Aux. output relays.
6. Wait 20 ms.
7. Close and maintain Contactor B output relay.
STOP/TRIP sequence:
1. Stop command received by the MM2 or a trip occurs.
2. Open Contactor B output relay.
If feedback is not received from the 1S, 2S or R contacts to the Contactor A, B or auxiliary relay Sta-
tus N.O. inputs within one second of closing Contactors A, B or the auxiliary relay, an OPEN CON-
TROL CIRCUIT alarm will occur. This will cause Contactors A, B and the auxiliary relay to open.
If feedback remains at any of the Status N.O. inputs for more than one second after opening the its
respective relay, a WELDED CONTACTOR alarm will occur.
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