Monitoring and diagnostics 23
Wear fields in the motor environment
Acquisition variables for wear fields
Contact erosion
The contact condition and thus the remaining life time of a
contactor can be determined directly based on the degree of
contact erosion. You can simultaneously use this to make a de-
termination about the condition of the power distribution, the
motor feeder, or the converter.
Number of starts, breaking current
The number of starts or the level of the breaking current indi-
rectly gives you information about the erosion of the swit-
ching contacts (empirical values, manufacturer's informati-
on). Using empirical values, it is also possible to make state-
ments about the load of the driven machine.
Number of operating hours (with/without limit value)
The runtime effects the wear of the motor and the machine.
The need for maintenance can be determined based on empi-
rical values, user knowledge or manufacturer's information.
Number of overload tripping operations
Overload tripping operations can have different causes. They
can give information about the condition of the machine or
plant, or they can signal an incorrect setting or motor selec-
tion. If necessary, the motor size should be changed.
Current limit/overload
Gradual changes in the overall application environment such
as pollution or bearing damage can cause increased current
consumption. Preventive maintenance can be planned and
carried out so that faults such as those caused by an overload
can be prevented.
Temperature
Corresponding sensors in the switchgear environment can
give information about the condition of the contacts. War-
ming of the ambient air can indicate that the switchgear is too
heavily utilized. One remedy is to avoid simultaneous activa-
tions, if applicable. The temperature of the motor or machine
can also indicate wear.
Ground fault or insulation detection
In isolated IT networks, faults can be detected in the motor or
supply line.
Underload/performance measurement
Performance measurements on machines can indicate broken
couplings, torn belts, slippage in the coupling bay, dry run-
ning of pumps, or fan filter contamination.
In addition, there is a series of special acquisition variables for
specific components such as pumps and general sensors who-
se measured values are recorded via analog inputs. In many
cases, the analysis of the described acquisition variables de-
pends on the user's estimation.
Acquisition variables which can be provided by Siemens protective devices and control cabinet devices
*
RLT stands for remaining life time monitoring
**
a power contactor is needed to activate the motor
0RWRUIHHGHU
0DFKLQH
HJ
SXPS
0RWRU
G_ST80_XX_00427
Acquisition variables Devices for condition monitoring
Motor contac-
tor with RLT *
SIRIUS com-
pact starter
3RA6
SIRIUS motor
starter M200D
3RW44 soft
starter
SIMOCODE pro
3UF7 **
Contact erosion; end of service life
● ●
Current detection
●●●
Performance recording/power factor
● ●
Number of starts/breaking current
●●●
Number of operating hours
●●●
Number of overload tripping operations
●●●
Current limit/overload
●●●
Temperature
●
Ground fault detection (int./ext.)
●
Underload/performance measurement
●
Maintenance timer
● ●
General sensor technology via analog inputs
●
Maintenance_PA_04_2010_en.book Seite 23 Dienstag, 6. September 2011 9:45 09
© Siemens AG 2011