The effectiveness of the disconnection is stored in the device's NV RAM and saved against auxiliary voltage
failure, i.e. the last information about the disconnection state is maintained when the power supply of the
device fails. When the power supply returns, the state of the binary input(s) for disconnection is checked
against the stored information. Only when they match will the protection functions become active again.
Inconsistencies are indicated as an alarm
Fail.Disconnect
(FNo 30145), and the life contact of the relay
remains open. The device cannot operate again until the state of the binary input(s) has been adapted to the
stored information.
The effect of the disconnection is that the currents from the disconnected measuring location — as far as they
are assigned to a side of the main protected object — are set to zero for those protection functions that are
assigned to this side. Currents arriving from the system after disconnecting the measuring location are not
effective here. The currents from 1-phase auxiliary measuring inputs allocated to the isolated measuring input
stay valid. Currents remain valid for those protection functions which are not assigned to a side.
No protection functions are blocked. The differential protection continues to work with the remaining avail-
able measured values. In the above example, the transformer can still operate through measuring location
M1, with the differential protection remaining fully effective.
Overcurrent protection functions assigned to a side continue to work without the current from the discon-
nected measuring location.
Overcurrent protection functions which are assigned exclusively to the disconnected measuring location (i.e.
not via a side definition) are supplied with the currents of the disconnected measuring location, i.e. continue
to operate with these currents. If necessary, they must be blocked by the information about disconnection
(either by corresponding assignment in the matrix of binary inputs or by user defined logical combination by
means of CFC).
The restricted earth fault protection, too, does not receive any more currents from the isolated measuring
location. If it is assigned to a side with two or more measuring locations, it can continue to work with the
currents from the remaining measuring location(s). If the isolated measuring location is the only 3-phase
source for the restricted earth fault protection, the starpoint current stays effective. This means that the
restricted earth fault protection will trip immediately if the starpoint current exceeds the pickup threshold.
Such a current must be a fault current in the protected object: it cannot come from the power system, which is
in fact isolated from the protected object.
Information List
No.
Information Type of
Informa-
tion
Comments
30080 M1 disconnected OUT Measurment location 1 is disconnected
30081 M2 disconnected OUT Measurment location 2 is disconnected
30082 M3 disconnected OUT Measurment location 3 is disconnected
30083 M4 disconnected OUT Measurment location 4 is disconnected
30084 M5 disconnected OUT Measurment location 5 is disconnected
30085 I1 disconnected OUT End 1 is disconnected
30086 I2 disconnected OUT End 2 is disconnected
30087 I3 disconnected OUT End 3 is disconnected
30088 I4 disconnected OUT End 4 is disconnected
30089 I5 disconnected OUT End 5 is disconnected
30090 I6 disconnected OUT End 6 is disconnected
30091 I7 disconnected OUT End 7 is disconnected
30092 I8 disconnected OUT End 8 is disconnected
30093 I9 disconnected OUT End 9 is disconnected
30094 I10disconnected OUT End 10 is disconnected
30095 I11disconnected OUT End 11 is disconnected
30096 I12disconnected OUT End 12 is disconnected
2.21.2
Functions
2.21 Disconnection of Measuring Locations
274 SIPROTEC 4, 7UT6x, Manual
C53000-G1176-C230-5, Edition 09.2016
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