ABB RELION REX640 Technical Manual page 1191

Protection and control

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1MRS759142 F

blocks in this document. The configuration can be written to the protection relay

once the mismatch is corrected.

Operation principle

The function can be enabled and disabled with 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 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

standstill condition.

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.

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

Technical Manual

Motor standstill A , the motor is considered to be in a

Protection related functions

Operation setting. The

ST_EMERG_ENA