Current Unbalance Protection - GE MM300 Instruction Manual

PROTECTION ELEMENTS
Current unbalance
protection
5–48
Ground Alarm Level
Range: 10 to 100% FLA in steps of 1%, or OFF, when Ground CT type is set to "Residual"
Range: 0.5 to 15.0 A in steps of 0.1 A, when Ground CT type is set to "CBCT 2000:1"
Default: OFF
The setpoint specifies the ground fault alarm pickup level. A value of "OFF" disables the
ground fault alarm function.
Ground Alarm Delay on Start
Range: 0 to 60 s in steps of 1 s
Default: 10 s
This setpoint specifies the time that the motor ground fault current must meet or exceed
pickup to generate a ground fault alarm.
Ground Alarm Delay on Run
Range: 0 to 60 s in steps of 1 s
Default: 10 s
This setpoint specifies the time that the motor ground fault current must meet or exceed
pickup to generate a ground fault alarm.
When an unbalance or phase current exceeds the setpoints, an alarm or trip condition is
generated.
The calculation method is as follows:
If I ≥
AV
If I
AV
Where:
I = average phase current
AV
I = current in a phase with maximum deviation from I
M
I = MOTOR FULL LOAD CURRENT setpoint
FLA
Current Unbalance Trip Level
Range: 4 to 40%, in steps of 1, or OFF
Default: 30%
This setpoint specifies the current unbalance trip pickup level. A value of "OFF" disables
the current unbalance trip function.
Current Unbalance Trip Delay
Range: 1 to 60 seconds in steps of 1
Default: 1 second
This setpoint specifies the time the motor unbalance current must meet or exceed
pickup to generate a trip.
Current Unbalance Lockout Trip
Range: Enabled, Disabled
Default: Disabled
This setpoint specifies whether the generated trip is considered a lockout or non-lockout
trip.
Current Unbalance Alarm Level
Range: 4 to 40%, in steps of 1, or OFF
Default: 15%
This setpoint specifies the current unbalance alarm pickup level. A value of "OFF"
disables the current unbalance alarm function.
|I - I |
M AV
: UB% =
I × 100%
FLA
I
AV
|I - I |
M AV
: UB% =
× 100%
≤ I
FLA
I
FLA
MM300 MOTOR MANAGEMENT SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETPOINTS
AV