GE Multilin MM300 - Current and voltage transformers

6 MM300 MOTOR MANAGEMENT SYSTEM – QUICKSTART GUIDE
CONFIGURATION SETPOINTS CHAPTER 4: SETPOINTS
Current and voltage transformers
Select the Home > Setpoints > Config > CT-VT page to edit the current and voltage
transformer setpoints.
Figure 4-5: Typical current and voltage transformer setpoints window
The following setpoints are available to configure the current and voltage transformers.
Phase CT Type (Mandatory Setpoint)
Range: None, 1 A Secondary, 5 A Secondary, Direct Connect
Default: Direct Connect
This setpoint specifies the phase CT connection type. The “Direct Connect” value
indicates that no phase CTs are used; instead, motor phase current passes directly
through the relay. The “Direct Connect” selection should never be used where full load
current is greater than 5.0 amps.
NOTE
NOTE:
If Direct Connect is selected and the FLA is set >5 A, a "FLA too high" message will be
displayed on the Status page.
CT Primary (Mandatory Setpoint)
Range: 5 to 1000 amps in steps of 1
Default: 5 amps
This setpoint specifies the phase CT primary current. It should never be less than the full
load current, and preferably no greater than twice than the full load current.
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 required.
NOTE
NOTE:
This setpoint is displayed only if the phase CT type is set to 1 A secondary or 5 A
secondary.
High Speed CT Primary
Range: 5 to 1000 amps in steps of 1
Default: 5 amps
This setpoint specifies the phase CT primary current when the motor is running at high
speed. It should never be less than the high speed full load current, and preferably no
greater than twice than the high speed full load current.
NOTE
NOTE:
This setpoint is displayed only if the phase CT type is set to 1 A secondary or 5 A
secondary and the motor starter type is two-speed.