Motor Start Up; Rated Current Of The Protected Unit - ABB REM 610 Technical Reference Manual

REM 610
4.1.1.7.
4.1.1.8.
16
Motor Protection Relay
Technical Reference Manual
The estimated time to the next possible motor start up, i.e. when the restart inhibit
signal is reset, can be accessed either via the HMI or the SPA bus.
Note!
If the restart inhibit function has been activated (SGF1/7=0), SGR3 will be
overridden.

Motor start up

A motor start-up situation is defined by means of the phase currents as follows:
• Motor start up begins (the motor start-up signal is activated) when the maximum
phase current rises from a value below 0.12 x I
value above 1.5 x I within less than 60 ms.
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• Motor start up ends (the motor start-up signal is reset) when all phase currents fall
below 1.25 x I and remain below for at least 200 ms.
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The start-up time of the latest motor start up can be accessed via the HMI and read
with SPA parameter V3.
The motor start-up signal is routed to the output contacts with the switches of
switchgroups SGR1...SGR5.
Note!
All operation indications on the LCD will be cleared when a motor start up begins.

Rated current of the protected unit

A scaling factor, PU scale, can be set for the phase currents. This will allow
differences between the rated current of the protected unit and that of the energizing
input. Consequently, the rated current of the relay can be set to equal the full load
current (FLC) of the motor.
The current settings of the protection functions are related to the scaled rated current,
I . The measured currents are presented either as primary values or as multiples of
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the scaled rated current. The current values in the recorded data are presented as
multiples of the rated current.
Note!
The scaling factor affects the operation accuracy of the protection functions, with the
exception of the earth-fault protection. The stated operation accuracy for each
protection function only applies when the scaling factor is 1.
Note!
If the PU scale is set to 0.5, the maximum measured rated current (FLC) is 25 x I
Note!
The PU scale does not affect the earth fault current, I
1MRS 752263-MUM
, i.e. the motor is at standstill, to a
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.
0
.
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