ABB RELION REX640 Technical Manual page 1002

Section 4
Protection functions
996
These two events do not take place at the same instant, that is, the CB main contact is
closed first, in which case the phase current value rises above 0.1 pu and after some
delay the CB auxiliary contact gives the information of the CB_CLOSED input. In
some cases, the CB_CLOSED input can be active but the value of current may not be
greater than the value of the Motor standstill A setting. To allow both possibilities, a
time slot of 200 milliseconds is provided for current and the CB_CLOSED input. If
both events occur during this time, the motor start-up is recognized.
The motor start-up ends either within the value of the Str over delay time setting from
the beginning of the start-up or the opening of CB or when the CB_CLOSED input is
deactivated. The operation of the MOT_START output signal in this operation mode
is as illustrated in Figure
This CB mode can be used in soft-started or slip ring motors for protection against a
large starting current, that is, a problem in starting and so on.
540.
1MRS759142 C
REX640
Technical Manual