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current transformers have different rated currents at the ends of the protected object,
set the highest rated current value for all ends.
This setting will not only have an impact on the displays of the operational measured
values in per cent, but it must also be exactly the same for each end of the pro-
tected object since it is the basis for the current comparison at the ends.
General Perfor-
The directional values (power, power factor, work and related min., max., mean and
mance Data
setpoint values), calculated in the operational measured values, are usually defined
with positive direction towards the protected object. This requires that the connection
polarity for the entire device was configured accordingly in the P.System Data 1
(compare also „Polarity of the Current Transformers", address 201). A different setting
of the „forward" direction for the protective functions and the positive direction for the
power etc. is also possible, e.g., so that the active power flow (from the line to the
busbar) is indicated in the positive sense. At address 1107 P,Q sign set the option
reversed. If the setting is not reversed (default), the positive direction for the
power etc. corresponds to the „forward" direction of the protective functions.
The reactance value X' as well as the capacitance value C' of the protected line are
required for compounding in overvoltage protection. Without these functions these pa-
rameters are of no consequence. The reactance value X' of the protected line is
entered in address 1111 as reference value x' in Ω/km if the distance unit was set as
kilometer or in Ω/mile if mile was selected as distance unit (address 236, see Section
2.1.2.1 at „Distance Unit"). The corresponding line length is entered in address 1113
Line Length in kilometres or miles. If the distance unit is changed at address 236,
the relevant line data have to be reset for the changed distance unit in address 1113
and in address 1113.
Capacity value C' of the line to be protected is entered in address 1112 as reference
value c' in µF/km, if km has been specified as length unit, or in µF/mile, if miles have
been specified as length unit (address 236, see Section 2.1.2.1 under „Distance
Unit"). If the distance unit is changed at address 236, the relevant line data have to be
reset for the changed distance unit in address 1112 and in address 1113.
Topological Data
The statements under this margin heading refer to protected lines (cables or overhead
for Transformers
lines) if a power transformer is situated within the protected zone, i.e. to models with
transformer option and if address 143 TRANSFORMER has been set to YES (see
(optional)
Section 2.1.1.2). If no transformer is part of the protected zone, this paragraph can be
passed over.
The topological data enable to relate all measured quantities to the nominal data of the
power transformer.
With address 1103 FullScaleVolt. you inform the device on the primary rated
voltage (phase-to-phase) of the transformer to be protected. This setting is also
needed for computing the current reference values of the differential protection.
Therefore, it is absolutely necessary to set the correct rated voltage for each end
of the protected object even if no voltages are applied to the relay.
In general, select the rated voltage of the transformer winding facing the device. How-
ever, if the protected transformer is equipped with a voltage tap changer at one wind-
ing, then do not use the rated voltage of that winding but the voltage that corresponds
to the mean value of the currents at the ends of the control range of the tap changer.
In this way the fault currents caused by voltage regulation are minimised.
7SD610 Manual
C53000-G1176-C145-4
2.1 General
41
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