GE MM300 Instruction Manual page 129

CHAPTER 5: SETPOINTS
MM300 MOTOR MANAGEMENT SYSTEM – INSTRUCTION MANUAL
Ground CT Type
Range: None, Residual, CBCT 2000:1
Default: CBCT 2000:1
This setpoint specifies the type of ground CT. Select "Residual" if the fourth CT Input on
the IO_A is connected to the residual of the Phase CT. Select 2000:1 if a zero sequence CT
(CBCT) is connected to the ground input on the CPU card.
CT Primary Turns
Range: 1 to 10
Default: 1
For smaller motors where the drawn current is very low, the motor leads may be
wrapped through the CT Primary with several turns thereby increasing the current seen
by the MM300 and as a result increasing the accuracy of the measurement. The value of
this setting should equal the number of turns on the CT Primary to display the correct
current value. Internally the current measurement will be divided by this setting.
Standard cut-off default is 20% (0.2pu) of CT primary. At CT primary less then 0.2pu,
primary CT turns are required and an appropriate current cut-off setpoint.
For example: using a 30:1 CT with 6A FLA gives 0.2A CT secondary @ FLA, the cut-off
must be lowered to 0.1A and a minimum of 3 primary turns are recommended.
Three Phase Voltage Connection
Range: Wye, Delta
Default: Wye
The method in which the IO_B voltage inputs are connected must be entered here. Note
that phase reversal is disabled for single VT operation. All voltages are assumed
balanced.
Auxiliary Voltage Connection (Mandatory Setpoint)
Range: VabVT, VbcVT, VcaVT, VanVT, VbnVT, VcnVT, VanDirect, VbnDirect, VcnDirect
Default: Vab VT
This setpoint specifies the control transformer connection to the motor supply voltage.
Auxiliary VT Primary
Range: 110 to 690 volts in steps of 1
Default: 415 volts
This setpoint specifies the primary voltage rating of the control transformer.
Auxiliary VT Secondary
Range: 110 to 300 volts in steps of 1
Default: 110 volts
This setpoint specifies the secondary voltage rating of the control transformer.
CONFIGURATION SETPOINTS
5–19