Direction Test Of The Phase Quantities (Current And Voltage Connection) - Siemens Reyrolle 7SR5 Manual

9.4 Direction Test of the Phase Quantities (Current and Voltage
Connection)
The proper connection of the current and voltage transformer is checked with load current flowing over the
line to be protected. For this, the line must be switched on. A load current of at least 0.1 of rated current has
to flow over the line; it should be resistive or resistive-inductive and the actual direction of the load current
has to be known. In case of doubt, meshed and ring systems should be opened or reconfigured. The line
remains switched on the for the duration of the measurements.
The direction determination in the device is derived directly from the measurement of applied currents and
voltages and is displayed in the device instruments. First make sure that the power measured values corre-
spond to the power direction. Conventionally, the forward direction (measuring direction) is considered to be
from the busbar toward the line but particularly for incoming circuits the network operator may prefer the
opposite direction to be used.
Using the power measured values displayed in the instruments at the device, make sure that it corresponds to
the expected power direction:
•
P is positive if the active (real) power flows into the line or protected object.
•
P is negative if the active (real) power flows to the busbar or out of the protected object.
•
Q is positive if the inductive reactive power flows into the line or protected object.
•
Q is negative if the inductive reactive power flows to the busbar or out of the protected object.
If the power measured values have a different sign than expected, then the power flow is opposite the current
direction convention that is defined by the applied settings. This can be the case, for example, at the opposite
end to the line where it may be considered as an incoming circuit.
If the values are not as expected, it may be due to the current transformer star point direction error or a
polarity reversal at the voltage connection. The convention direction can be reversed by configuration of
device settings but this setting should not be used to disguise a wiring error.
Reyrolle 7SR5, Transformer Protection Device, Device Manual
C53000-G7040-C015-1, Edition 11.2019

9.4 Direction Test of the Phase Quantities (Current and Voltage Connection)

Functional Tests
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