5.5.3
Functionality
An emergency condition can arise in cases where the motor needs to be started
despite knowing that this can increase the temperature above limits or cause a
thermal overload that can damage the motor. The emergency start-up function
ESMGAPC allows motor start-ups during such emergency conditions. ESMGAPC is
only to force the protection relay to allow the restarting of the motor. After the
emergency start input is activated, the motor can be started normally. ESMGAPC
itself does not actually restart the motor.
The function contains a blocking functionality. It is possible to block function
outputs, timer or the function itself, if desired.
5.5.4
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of ESMGAPC can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
Figure 439: Functional module diagram
Standstill detector
The module detects if the motor is in a standstill condition. The standstill condition
can be detected based on the phase current values. If all three phase currents
are below the set value of
Motor standstill A, the motor is considered to be in a
standstill condition.
Timer
The timer is a fixed 10-minute timer that is activated when the
ST_EMERG_RQ
input
is activated and motor standstill condition is fulfilled. Thus, the activation of the
ST_EMERG_RQ
input activates the
ST_EMERG_ENA
output, provided that the motor is
in a standstill condition. The
ST_EMERG_ENA
output remains active for 10 minutes
or as long as the
ST_EMERG_RQ
input is high, whichever takes longer.
The activation of the
BLOCK
input blocks and also resets the timer.
The function also provides the
ST_EMERG_ENA
output change date and time,
T_ST_EMERG
. The information is available in the monitored data view.
5.5.5
Application
If the motor needs to be started in an emergency condition at the risk of damaging
the motor, all the external restart inhibits are ignored, allowing the motor to be
Protection related functions
1MRS757644 H
826
620 series
Technical Manual
