GE M60 Instruction Manual page 352

5.7 CONTROL ELEMENTS
d) BROKEN ROTOR BAR DETECTION

PATH: SETTINGS CONTROL ELEMENTS
 BROKEN ROTOR BAR

5
The broken rotor bar detection function uses the same source as other motor protection functions. This source is defined by
the 
SYSTEM SETUP
bar detection function to operate:
• Phase currents must be configured on this source for the broken rotor bar detection function.
• The
AC INPUT WAVEFORMS
• The thermal model must be enabled.
This function monitors only phase A current.
When the broken rotor bar detection function is enabled, an alarm is initiated once the value of ratio of the broken bar
related sideband component versus the system fundamental component is greater than the pickup level for two consecu-
tive measurements. To reduce probability of a false alarm (caused by impairments other than a rotor bar failure), the ele-
ment is active only if the following conditions hold.
• The motor status is "Running" and the motor load is between preset minimum acceptable value and a value just below
the overload (defined by
Trying to detect the broken rotor bar during a motor start will return an incorrect result because of the rapid movement
of broken rotor bar components and a heavy change in the motor current. On the other hand, while the motor load is
small, there is not enough resolution to accurately calculate a miniscule spectral component caused by a rotor bar fail-
ure.
5-214

MONITORING ELEMENTS
BROKEN ROTOR BAR
FUNCTION: Disabled
START OF BRB
MESSAGE
OFFSET:
END OF BRB
MESSAGE
OFFSET:
BRB START BLOCK
MESSAGE
DELAY: 60.00 s
MINIMUM MOTOR LOAD:
MESSAGE
0.70 x FLA
MAX. LOAD DEVIATION:
MESSAGE
0.10 x FLA
MAXIMUM CURRENT
MESSAGE
UNBALANCE:
BROKEN ROTOR BAR
MESSAGE
PICKUP: -40 dB
BROKEN ROTOR BAR
MESSAGE
RESET DLY:
BRB BLOCK:
MESSAGE
Off
BROKEN ROTOR BAR
MESSAGE
TARGET: Self-reset
BROKEN ROTOR BAR
MESSAGE
EVENTS: Disabled

MOTOR MOTOR LINE SOURCE
oscillography setting must not be "Off".
MOTOR FULL LOAD AMPS
M60 Motor Protection System

BROKEN ROTOR BAR
Range: Disabled, Enabled
Range: –12.00 to 11.99 Hz in steps of 0.01
0.40 Hz
Range: –11.99 to 12.00 Hz in steps of 0.01
2.00 Hz
Range: 0.00 to 600.00 s in steps of 0.01
Range: 0.50 to 1.00 × FLA in steps of 0.01
Range: 0.50 to 1.00 × FLA in steps of 0.01
Range: 0.0 to 100.0% in steps of 0.1
15.0%
Range: –60 to –12 dB in steps of 1
Range: 0.00 to 600.00 s in steps of 0.01
1.00 s
Range: FlexLogic™ operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
setting. The following items must addressed for the broken rotor
× ).
MOTOR OVERLOAD FACTOR
5 SETTINGS
GE Multilin