Mm3 Sequence - GE MM3 Instruction Manual

9 STARTER TYPES 9.5 PRIMARY RESISTANCE STARTER

9.5.2 MM3 SEQUENCE

START sequence:
1. Start command received by the MM3 (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 MM3 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 MM3 is interrupted, all output relays on the MM3 will de-energize causing them to open
and stop the motor. The MM3 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 sec-
ond 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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GE Power Management MM3 Motor Manager 3 9-15