ABB RELION REX640, Техническое руководство, Страница: 1191 / 1960

blocks in this document. The configuration can be written to the protection relay
once the mismatch is corrected.
5.6.5 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.
I3P
Standstill
detector
ST_EMERG_RQ
ST_EMERG_ENA
BLOCK
Timer
I_A
I_B
I_C
t
Figure 680: 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.
5.6.6 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
restarted. Furthermore, if the calculated thermal level is higher than the restart
inhibit level at an emergency start condition, the calculated thermal level is set
slightly below the restart inhibit level. Also, if the register value of the cumulative
start-up time counter exceeds the restart inhibit level, the value is set slightly below
the restart disable value to allow at least one motor start-up.
The activation of the
ST_EMERG_RQ
digital input allows to perform emergency start.
The protection relay is forced to a state which allows the restart of motor, and
the operator can now restart the motor. A new emergency start cannot be made
1MRS759142 F Protection related functions
REX640
Technical Manual
1191