2.10 Defrosting Protection
117
7ST6 Manual
E50417-G1176-C251-A3
2.10.2 Setting Notes
Preconditions
When setting the general power system data (Power System Data 1, refer to Section
2.1.3.1) a number of parameters regarding the measured quantities and the operating
mode of the defrosting protection function must be applied.
This concerns the following parameters:
201
CT Starpoint
Current direction of the current transformer
202
CT PRIMARY
CT rated primary current
211
IX CT STARPOINT
Current direction of the current transformer
212
IX CT PRIMARY
CT rated primary current
203
CT SECONDARY
CT rated secondary current
General
The defrosting operation can only operate if address
144
FCT DEFROSTING
has been
set to
Enabled
and the parameter
Defrosting
is set to
ON
(address
4301
).
The measured values of the differential current
„Id =“
and the restraint current
„Ir
=“
are only available or will only be calculated if the defrosting parameter
Defrosting
(address
4301
) has been set to
ON
.
The defrosting protection can be switched on or off via the binary inputs
„>Defrost
ON“
(FNo. 13960) and
„>Defrost OFF“
(FNo. 13961), or via the system interface.
For control via the system interface, the internal single-point indication
„Defrost
ON“
(FNo. 13963) is used.
Blocking
There are various possibilities for blocking the defrosting protection. If the protection
is blocked, only the TRIP indication
„Diff TRIP“
(Fno. 13975) will be blocked. All
other indications are output as before.
The defrosting protection can be blocked locally from the operator panel, using the
binary input or system interface.
For blocking via the system interface or the operator panel, the internal single-point
indication
„Defrost block“
(FNo. 13978) is used. For blocking via a binary input,
the signal
„>BLOCK Defrost“
(FNo. 13962) must be configured to the appropriate
binary input.
If defrosting has been blocked from more than one source, the blocking must be reset
from all sources to become ineffective again. When the defrosting protection is
blocked, the indication
„Defrost blk“
(FNo. 13965) is output.
Differential Protec-
tion
For the differential protection, you must set as pickup current the differential current
Id, which is permanently present in normal service. The pickup current
4302
ID>
is
set somewhat higher (approx. 20 %) than the maximum differential current Id that is
to be expected in normal service.
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