ABB RELION REX640 Technical Manual page 1001

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1MRS759142 C

Technical Manual

The Operation mode setting in the "IIt, CB" mode enables the function to calculate the

value of the thermal stress when a start-up is monitored in addition to the CB_CLOSED

In the "IIt & stall" mode, the function calculates the thermal stress of the motor during

the start-up condition. The start-up condition is detected by monitoring the TRMS

In the "IIt & stall, CB" mode, the function calculates the thermal stress of the motor

during the start-up condition but the start-up condition is detected by monitoring the

TRMS current as well as the circuit breaker status.

In both the "IIt & stall" and "IIt & stall, CB" mode, the function also checks for motor

stalling by monitoring the speed switch.

When the measured current value is used for start-up supervision in the "IIt" and "IIt

& stall" modes, the module initially recognizes the de-energized condition of the

motor when the values of all three phase currents are less than Motor standstill A for

longer than 100 milliseconds. If any of the phase currents of the de-energized

condition rises to a value equal to or greater than Motor standstill A, the MOT_START

output signal is activated indicating that the motor start-up is in progress. The

MOT_START output remains active until the values of all three phase currents drop

below 90 percent of the set value of Start detection A and remain below that level for

a time of Str over delay time, that is, until the start-up situation is over.

GUID-15B19852-C3E8-4E73-8E0F-E208AA22B4B2 V1 EN

Functionality of start-up supervision in the "IIt and IIt&stall" mode

In case of the "IIt, CB" or "IIt & stall, CB" modes, the function initially recognizes the

de-energized condition of the motor when the value of all three phase currents is below

the value of the Motor standstill A setting for 100 milliseconds. The beginning of the

motor start-up is recognized when CB is closed, that is, when the CB_CLOSED input

is activated and at least one phase current value exceeds the Motor standstill A setting.

Protection functions

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