ABB REC 561 User Manual page 389

1MRK 580 151-XEN
Page 6 - 104
Interlocking
On the station MMI an override function exists, which can be used to
bypass the interlocking function if not all available data for the condition
are valid.
For all interlocking modules these general rules apply:
• The interlocking conditions for opening or closing of disconnectors
and earthing switches are always identical.
• Earthing switches, which can earth an incoming line directly or via
circuit breakers (rapid earthing switches), are interlocked only with
reference to the conditions in the associated station, not with refer-
ence to the state of the line. So a line voltage indication is included
into line interlocking modules. If there is no line voltage supervision
within the bay, then the appropriate inputs must be set to no voltage,
and the operator must take care about this manually.
• Earthing switches near a circuit breaker (CB) can only be operated if
disconnectors on both sides of the CB are open. Otherwise, earthing
switches can only be operated on isolated points (that is, no other
switch is connected).
• Disconnectors cannot break power current or connect different volt-
age systems. Disconnectors in series with a circuit breaker can only
be operated if the circuit breaker is open, or if the disconnectors
close a loop (uninterrupted bus bar transfer), or if they are com-
pletely earthed on both sides of the circuit breaker. Other disconnec-
tors can be operated if one side is completely isolated, or if they
close a loop, or if they are earthed on both sides.
• Circuit breaker closing is only interlocked against running discon-
nectors in its bay or additionally in a transformer bay against the dis-
connectors and earthing switch on the other side of the transformer,
if there is no disconnector between CB and transformer.
• Circuit breaker opening is only interlocked at a bus-coupler bay, if a
bus bar transfer is in progress.
ABB Network Partner AB
Version 1.0-00