in PCM600. Similarly, the
TEMP_RL
output of MPTTR must be connected to the
TEMP_RL
input of this function in Application Configuration in PCM600.
When the emergency start signal
START_EMERG
is set high and if the value of the
cold or warm counter is above its start value setting, the value of the counter is
set one count less than the respective maximum number of start value setting. This
disables
BLK_RESTART
and
OPERATE
which makes the restart of motor possible.
The values can be reset by activating the
RESET
binary input. The activation of the
RESET
input also resets the counter decrease timer. The counter value can also be
reset on the Clear menu.
Limit supervision
This module compares the motor cold and warm count to the set
Max Num cold
start and Max Num warm start, respectively. The
BLK_RESTART
output is activated
when either the cold or the warm start counter reaches the set
Max Num cold start
or
Max Num warm start, respectively. The
OPERATE
output is activated when either
the cold or the warm start counter exceeds the set
Max Num cold start or Max Num
warm start, respectively.
When the
BLK_RESTART
output is active, T_RST_ENA shows the possible time for
the next restart. The value of T_RST_ENA is calculated as the time left for both
counters to decrease below their maximum number of starts.
Activation of the
BLOCK
input blocks both
OPERATE
and
BLK_RESTART
outputs.
6.7.5
Application
Repeated motor starts increase the temperature to a high value in the stator or
rotor windings, or both, unless enough time is allowed for the heat to dissipate.
To ensure a safe operation, it is necessary to provide a fixed-time interval between
starts or limit the number of starts within a period of time. This is why the motor
manufacturers have restrictions on how many starts are allowed in a defined time
interval.
This function counts the number of cold and warm starts and provides a block
restart signal when the number of starts reaches the permitted limit. The customer
can use this signal for blocking a new start operation. An operate signal is also
available which can be used to disconnect the motor when the number of starts
exceeds the limit.
6.7.6
Signals
Supervision functions
1MRS759142 F
1344
REX640
Technical Manual