CHAPTER 5: SETTINGS
CONTROL ELEMENTS
M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
5-317
5
START OF BRB OFFSET
— This setting specifies the beginning of the frequency range where the spectral component due to a
rotor bar failure is searched. The beginning of the frequency range is defined as follows, where f
1
is the system frequency
and f
start_offset
is this setting.
f
start
= f
1
+ f
start_offset
Eq. 5-49
If the upper sideband is to be measured, this setting is programmed as follows, where f
1
is the system frequency and s is
the motor slip at full load.
f
start_offset
= 2sf
1
- max(0.3, min(2sf
1
- 0.4, 1.0))
Eq. 5-50
For example, if the full load slip is 0.01, program this setting as follows for a 60 Hz power system.
f
start_offset
= 2sf
1
- max(0.3, min(2sf
1
- 0.4, 1.0))
= 2 x 0.01 x 60 Hz - 0.8 = 0.40 Hz
Eq. 5-51
If the lower sideband is to be measured, this setting is programmed as follows, where f
1
is the system frequency and s is
the motor slip at full load.
f
start_offset
= -2sf
1
- max(0.3, min(2sf
1
- 0.4, 1.0))
Eq. 5-52
Using the same values from previous example, this value is programmed as follows.
f
start_offset
= -2sf
1
- max(0.3, min(2sf
1
- 0.4, 1.0))
= -2 x 0.01 x 60 Hz - 0.8 = -2.00 Hz
Eq. 5-53
END OF BRB OFFSET
— This setting specifies the end of the frequency range where the spectral component due to a rotor
bar failure is searched. The end of the frequency range is defined as follows, where f
1
is the system frequency and
f
end_offset
is this setting.
f
end
= f
1
+ f
end_offset
Eq. 5-54
If the upper sideband is to be measured, this setting is programmed as follows, where f
1
is the system frequency and s is
the motor slip at full load.
f
end_offset
= 2sf
1
+ max(0.3, min(2sf
1
- 0.4, 1.0))
Eq. 5-55
For example, if the full load slip is 0.01, program this setting as follows for a 60 Hz power system.
f
end_offset
= 2sf
1
+ max(0.3, min(2sf
1
- 0.4, 1.0))
= 2 x 0.01 x 60 Hz + 0.8 = 2.00 Hz
Eq. 5-56
If the lower sideband is to be measured, this setting is programmed as follows, where f
1
is the system frequency and s is
the motor slip at full load.
f
end_offset
= -2sf
1
+ max(0.3, min(2sf
1
- 0.4, 1.0))
Eq. 5-57
Using the same values from previous example, this value is programmed as follows.
f
end_offset
= -2sf
1
+ max(0.3, min(2sf
1
- 0.4, 1.0))
= -2 x 0.01 x 60 Hz + 0.8 = -0.40 Hz
Eq. 5-58
BRB START BLOCK DELAY
— This setting is used to block the broken rotor bar detection function while the motor is starting for
the time specified. 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 determine 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 algorithm 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 cannot
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 normally is set to a level between –54 dB (very likely, a cracked rotor bar) and –50 dB (probably a broken
rotor bar).
Содержание M60
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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 ...
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