GE M60 Instruction Manual page 354

5.7 CONTROL ELEMENTS
• BRB START BLOCK DELAY: This setting is used to block the broken rotor bar detection function while the motor is
starting for the specified time. This ensures that the broken rotor bar element is active only when the motor is running.
• MINIMUM MOTOR LOAD: When the motor load is less than the value specified by this setting, the data acquisition of
the broken rotor bar detection function is blocked. The broken rotor bar detection algorithm cannot accurately deter-
mine the broken rotor bar spectral component when a motor is lightly loaded.
• MAX. LOAD DEVIATION: When the standard deviation of the motor load is greater than the value specified by this
setting, the data acquisition of the broken rotor bar detection function is blocked. The broken rotor bar detection algo-
rithm cannot accurately determine the broken rotor bar spectral component when the motor load varies.
• MAXIMUM CURRENT UNBALANCE: When the current unbalance is greater than the value specified by this setting,
the data acquisition of the broken rotor bar detection function is blocked. The broken rotor bar detection algorithm can-
not accurately determine the broken rotor bar spectral component in a current unbalance situation.
• BROKEN ROTOR BAR PICKUP: This setting specifies the pickup threshold for the broken rotor bar detection feature.
The pickup threshold should normally be set to a level between –54 dB (very likely, a cracked rotor bar) and –50 dB
(probably a broken rotor bar).
• BROKEN ROTOR BAR RESET DLY: This setting specifies a time delay to reset the broken rotor bar detection fea-
ture. This setting can be left at its default value since the element updates its state one to two times per minute.
• BRB BLOCK: This setting selects a FlexLogic™ operand used to block the broken rotor bar detection feature. Typi-
cally, a panel cut-off switch or other user-specified conditions blocks this function.
5
5-216 M60 Motor Protection System
5 SETTINGS
GE Multilin