6.7.3 Functionality
The motor start counter function MSCPMRI counts the number of motor starts
and distinguishes between cold and warm starts. The allowed number is generally
provided by the motor manufacturer. The motor starting MOT_START output of the
motor start-up supervision function is used to count the starts. The motor thermal
level TEMP_RL calculated by the thermal overload protection is used to distinguish
between a cold and warm start.
The function contains a blocking functionality. It is possible to block the function
outputs or the function itself.
6.7.4 Operation principle
The function can be enabled and disabled with the
Operation
setting. The
corresponding parameter values are "on" and "off".
The operation of MSCPMRI can be described with a module diagram. All the
modules in the diagram are explained in the next sections.
BLOCK
OPERATE
BLK_RESTART
MOT_RUN
Motor start
counter
RESET
Limit
supervision
TEMP_RL
START_EMERG
Figure 763: Functional module diagram
Motor start counter
This module counts the number of motor starts. The value of the cold count
COLD_COUNT and warm count WARM_COUNT is available in the Monitored data
view. On the rising edge of MOT_RUN, the module increments the cold start counter.
If the thermal content available at the TEMP_RL input is above the set
Warm start
level
when the rising edge of the MOT_RUN input is received, both cold and warm
start counter values are incremented.
If
Operation
of the thermal overload protection for motors function
MPTTR is set as "Off", the TEMP_RL value is not available. In this case,
the warm start counter does not increase.
The counter decrease timer also starts at the first increment of the cold start
counter (that is the first time when the counter increases from zero). When
Cnt
decrease time
elapses, both cold and warm start counters decrease by one and the
counter decrease timer restarts. This is repeated until both cold and warm counters
are zero.
When the motor is not in operation, that is, the motor is in stop condition, it takes
more time to cool. During such condition
Cnt decrease time
is multiplied by a
Cnt
Dec timer Mult
setting.
The motor start detection is available at the MOT_START output of the motor
start-up supervision function STTPMSU. The MOT_START output of STTPMSU must
be connected to the MOT_RUN input of this function in Application Configuration
1MRS759142 F
Supervision functions
REX640
Technical Manual
1343
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