4–286
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
MONITORING
CHAPTER 4: SETPOINTS
ESA application for Rolling Element Bearing Fault Detection
The faults occurring in motor bearings are generally due to the excessive load, rise of
temperature inside the bearing, use of bad lubricant and so on. The bearing consists
mainly of the outer race and inner race ways, the balls and cage; this assures equal
distance between the balls. The different faults that may occur in a bearing can be
indicated as a single parameter based on any affected component as shown in the next
figure.
•
Outer raceway defect
•
Inner raceway defect
•
Ball defect
Figure 4-119: Ball bearing details
The Bearing Flt element uses FFT computation on the current signal to detect bearing
failure on an electrical machine. The operating condition can be defined as: Computing
vibration frequency related to bearing damage using this equation.
Eq. 27
Compute stator current frequency related to bearing damage using the following
equation.
F_bearing = F_supply ± k * F_vibration
Eq. 28
k is any integer: 1,2,3,…
Identifying peak magnitudes or energy in dB at the stator current frequencies and
calculating change in dB magnitude for baseline (healthy mode) peak magnitudes or
energy at the corresponding stator current frequencies in dB for each load bin is given by
the equations
Change in Energy dB
and
Change in Peak Magnitude dB
.
Change in Energy dB = Energy dB (Latest) – Energy dB (Baseline)
Eq. 29
Change in Peak Magnitude dB = Peak magnitude dB (Latest) – Peak magnitude dB (Baseline)
Eq. 30
°
°
°
¯
°
°
°
®
−
+
−
=
damage)
(ball
)
1
(
60
race)
(outer
)
1
(
60
2
race)
(inner
)
1
(
60
2
2
2
c
b
r
b
c
c
b
r
b
c
b
r
b
vib
D
D
D
D
D
D
N
D
D
N
f
ω
ω
ω
Summary of Contents for 869
Page 10: ...VIII 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL ...
Page 127: ...CHAPTER 3 INTERFACES SOFTWARE INTERFACE 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL 3 49 ...
Page 129: ...CHAPTER 3 INTERFACES SOFTWARE INTERFACE 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL 3 51 ...
Page 538: ...4 406 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL TESTING CHAPTER 4 SETPOINTS ...
Page 578: ...6 22 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL FLEXELEMENTS CHAPTER 6 METERING ...
Page 592: ...7 14 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL CLEAR RECORDS CHAPTER 7 RECORDS ...