8.2.3.6
Reservation input (RESIN)
M16678-3 v3
With the
FutureUse
parameter set to
Bay future use
the function can handle bays
not yet installed in the SA system.
8.3
Interlocking
IP15572-1 v2
M13530-4 v4
The main purpose of switchgear interlocking is:
•
To avoid the dangerous or damaging operation of switchgear
•
To enforce restrictions on the operation of the substation for other reasons for
example, load configuration. Examples of the latter are to limit the number of
parallel transformers to a maximum of two or to ensure that energizing is
always from one side, for example, the high voltage side of a transformer.
This section only deals with the first point, and only with restrictions caused by
switching devices other than the one to be controlled. This means that switch
interlock, because of device alarms, is not included in this section.
Disconnectors and earthing switches have a limited switching capacity.
Disconnectors may therefore only operate:
•
With basically zero current. The circuit is open on one side and has a small
extension. The capacitive current is small (for example, < 5A) and power
transformers with inrush current are not allowed.
•
To connect or disconnect a parallel circuit carrying load current. The switching
voltage across the open contacts is thus virtually zero, thanks to the parallel
circuit (for example, < 1% of rated voltage). Paralleling of power transformers
is not allowed.
Earthing switches are allowed to connect and disconnect earthing of isolated
points. Due to capacitive or inductive coupling there may be some voltage (for
example < 40% of rated voltage) before earthing and some current (for example <
100A) after earthing of a line.
Circuit breakers are usually not interlocked. Closing is only interlocked against
running disconnectors in the same bay, and the bus-coupler opening is interlocked
during a busbar transfer.
The positions of all switching devices in a bay and from some other bays determine
the conditions for operational interlocking. Conditions from other stations are
usually not available. Therefore, a line earthing switch is usually not fully
interlocked. The operator must be convinced that the line is not energized from the
other side before closing the earthing switch. As an option, a voltage indication can
be used for interlocking. Take care to avoid a dangerous
enable
condition at the
loss of a VT secondary voltage, for example, because of a blown fuse.
1MRK 511 423-UEN A
Section 8
Control
Bay control REC650 2.2 IEC
127
Application manual
