Omron K6CM User Manual page 74

3 Measuring and monitoring System
Note 1. When you use an inverter to drive the motor, you may not be able to monitor the abnormality of the
motor or load using degradation level 1. If that happens, monitor it using degradation level 2.
Motor
condition
Direct
connec-
tion to
commer-
cial
power
supply
With
inverter
The above is an example and degradation level 1 is reference value. Degradation level 1 and the current
wave may vary depends on the motor.
2. Degradation level 1 may vary when the motor is driven by the inverter. In that case, slightly shift the
inverter drive frequency.
Also always measure and monitor degradation level 1 at the same inverter drive frequency.
3 - 20
Normal
The load balance is stable.
Degradation level 1: 8
Normal Ideal sine wave
[sec]
Zoom up
Since the current waveform is
almost matches the ideal sine
wave, the value of degrada-
tion level 1 will small.
Degradation level 1: 50
Normal Ideal sine wave
[sec]
Zoom up
An inverter control causes the
current waveform to deviate
from the ideal sine wave.
Even when the motor drive is
in normal condition, the value
of degradation level 1 will
large.
Low-level degradation
The load balance is lost,
and the force is applied
unevenly to the motor shaft.
A small
foreign matter
is attached.
Example: Small amount of a
foreign matter attached to
the propeller fan
Degradation level 1: 24
Low-level
Ideal sine wave
degradation
[sec]
Zoom up
Even in Low-level degradation,
since the current waveform
deviates from the ideal sine
wave, so the value of degrada-
tion level 1 will higher than that
in the normal condition.
Degradation level 1: 51
Ideal sine wave
Normal
[sec]
Zoom up
An inverter control causes the
current waveform to deviate
largely from the ideal sine
wave. Therefore Low-level
degradation is not shown, and
the value of degradation level
1 will not be changed largely.
K6CM Motor Condition Monitoring Device User's Manual (N219)
High-level degradation
The load balance is signifi-
cantly lost, and the large
force is applied unevenly to
the motor shaft.
A large
foreign matter
is attached.
Example: Adhesion of a for-
eign matter, or damage of
propeller fan
Degradation level 1: 56
High-level
Ideal sine wave
degradation
[sec]
Zoom up
In High-level degradation,
since the current waveform
deviates largely from the ideal
sine wave, the value of degra-
dation level 1 will large.
Degradation level 1: 61
High-level Ideal sine wave
degradation
[sec]
Zoom up
An inverter control causes the cur-
rent waveform to deviate largely
from the ideal sine wave. Also, the
deviation from the ideal sine wave
is large due to the Hi-level degra-
dation. Therefore the value of
degradation level 1 will large.