Siemens SIPROTEC 7SS523 V3.2 Manual page 265

Maintenance of bay
Bay out of service
7.1.3.2 2-Bay Bus Coupler With 2 Current Transformers
7.1.3.3 2-Bay Bus Coupler With one Current Transformer
7.1.3.4 Connection
This function is applied during isolator maintenance when the isolator feed-back sig-
nals do not correspond with the isolator switching state (e.g. when testing the auxiliary
contacts or when the auxiliary supply for isolator status signals is switched off).
The feeder remains in service during this time and consequently is part of the busbar
protection measurement.
"Maintenance of bay" results in a freeze of the current isolator switching state in this
bay. The further isolator monitoring in this bay and resulting signals are blocked. A sig-
nal "Isolator operation prohibited" is generated.
The maintenance mode is activated in each bay unit. There is always one binary in out
by means of which the corresponding bay unit can switch the maintenance mode for
the configured isolator on or off.
Individual switchgear (isolators, circuit breakers) can be excluded from the mainte-
nance mode by means of a setting parameter.
For the function "Bay out of service", the binary inputs of the two bay units are com-
bined by a logical OR, i.e. the connection to one binary input is sufficient.
With a 2-bay bus coupler with 2 current transformers, each bay unit is connected to its
corresponding current transformer (usually overlapping).
If more than 5 isolators have to be monitored, in the DIGSI plant Configuration a cou-
pler must also be equipped at the distributed busbar and breaker failure protection
SIPROTEC 7SS52 V4 with two bay units. Distribute the isolators of the bay to 2 bay
units (see also Configuration notes in Chapter 4.8, page 81).
If you have couplers with one transformer, connect the current inputs of the bay
units in series per phase (Figure 7-1, page 250).
Record the isolator positions according to the configuration via the binary inputs of
the single bay units.
Connect the TRIP command and transfer trip contacts of both bay units in parallel.
In this case also connect further binary input functions (e.g. CBF initiation, CBF re-
lease, TRIP release) in parallel.
Installation and Commissioning
7SS52 V4 Manual
C53000-G1176-C182-1
249