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M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CONTROL ELEMENTS
CHAPTER 5: SETTINGS
5
The broken rotor bar detection function uses the same source as other motor protection functions. This source is defined
by the
SYSTEM SETUP
MOTOR
MOTOR LINE SOURCE
setting. The following items must addressed for the broken rotor
bar detection function to operate:
•
Phase Currents must be configured on this source for the broken rotor bar detection function
•
The
AC INPUT WAVEFORMS
oscillography setting must not be “Off”
•
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
consecutive measurements. To reduce probability of a false alarm (caused by impairments other than a rotor bar failure),
the element 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
MOTOR FULL LOAD AMPS
×
MOTOR OVERLOAD FACTOR
).
Trying to detect the broken rotor bar during a motor start returns 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
failure.
•
The motor load is steady.
Variations in motor load cause spectral components that can be misinterpreted as rotor bar failure. Instantaneous
motor load values are collected alongside with data for the broken rotor bar algorithm to prevent this from happening.
The average motor load and its standard deviation are calculated. If the standard deviation is greater than its
corresponding setting, the data set is discarded and the broken bar algorithm is not initiated.
•
The motor current unbalance is below a corresponding setpoint.
The excessive current unbalance stresses the motor, and it can cause false broken rotor bar detection.
It is recommended that frequency tracking be enabled to avoid possible false broken rotor bar detection results when the
system frequency drifts from the nominal frequency.
The following settings are available for the broken rotor bar detection element.
BRB START BLOCK
DELAY: 60.00 s
Range: 0.00 to 600.00 s in steps of 0.01
MINIMUM MOTOR LOAD:
0.70 x FLA
Range: 0.50 to 1.00 × FLA in steps of 0.01
MAX. LOAD DEVIATION:
0.10 x FLA
Range: 0.50 to 1.00 × FLA in steps of 0.01
MAXIMUM CURRENT
UNBALANCE: 15.0%
Range: 0.0 to 100.0% in steps of 0.1
BROKEN ROTOR BAR
PICKUP: -40 dB
Range: –60 to –12 dB in steps of 1
BROKEN ROTOR BAR
RESET DLY: 1.00 s
Range: 0.00 to 600.00 s in steps of 0.01
BRB BLOCK:
Off
Range: FlexLogic operand
BROKEN ROTOR BAR
TARGET: Self-reset
Range: Self-reset, Latched, Disabled
BROKEN ROTOR BAR
EVENTS: Disabled
Range: Disabled, Enabled
The M60 is provided with optional broken rotor bar detection. This feature is specified as an option at the time
of ordering. See the Order Codes section in chapter 2 for details.
Содержание M60
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Страница 14: ...1 4 M60 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL FOR FURTHER ASSISTANCE CHAPTER 1 INTRODUCTION 1 ...
Страница 208: ...4 88 M60 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL FLEXLOGIC DESIGN USING ENGINEER CHAPTER 4 INTERFACES 4 ...
Страница 494: ...5 286 M60 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL CONTROL ELEMENTS CHAPTER 5 SETTINGS 5 Figure 5 158 Time out mode ...
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Страница 596: ...7 14 M60 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL TARGETS MENU CHAPTER 7 COMMANDS AND TARGETS 7 ...
Страница 602: ...9 4 M60 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL SATURATION DETECTOR CHAPTER 9 THEORY OF OPERATION 9 ...
Страница 652: ...C 6 M60 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL COMMAND LINE INTERFACE APPENDIX C COMMAND LINE INTERFACE C ...
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