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Mounting and Commissioning
3.3 Commissioning
[lastscheinleistung-290803-st, 1, en_US]
Figure 3-30
•
The power measurement provides an initial indication as to whether the measured values of one end
have the correct polarity.
–
If the reactive power is correct but the active power has the wrong sign, cyclic phase swapping of
the currents (right) or of the voltages (left) might be the cause.
–
If the active power direction is correct but the reactive power has the wrong sign, cyclic phase swap-
ping of the currents (left) or of the voltages (right) might be the cause.
–
If both the real power as well as the reactive power have the wrong sign, the polarity in address 201
CT Starpoint must be checked and rectified.
The phase angles between currents and voltages must also be conclusive. All three phase angles φ (V
) must be approximately the same and represent the operating status. In the event of power in the
Ι
Lx
direction of the protected object, they correspond to the current phase displacement (cos ϕ positive); in
the event of power in the direction of the busbar they are higher by 180° (cos φ negative). However,
charging currents might have to be taken into consideration (see above).
•
The measurements may have to be repeated after correcting the connections.
•
The above described tests of the measured values also have to be performed at the other end of the
tested current path. The current and voltage values as well as the phase angles of the other end can also
be read out locally as percentage values. Please observe that currents flowing through the object
(without charging currents) ideally have opposite signs at both ends, i.e. they are turned by 180°.
•
The protected object is now switched off, i.e. the circuit breakers are opened.
Polarity Check for the Current Measuring Input Ι
If the standard connection of the device is used whereby current input Ι
of current transformers (refer also to the connection circuit diagram in the Appendix
then the correct polarity of the ground current path in general automatically results.
If, however, the current Ι
current is necessary.
Otherwise the test is done with a disconnected trip circuit and primary load current. It must be noted that
during all simulations that do not exactly correspond with situations that may occur in practice, the non-
symmetry of measured values may cause the measured value monitoring to pick up. This must therefore be
ignored during such tests.
242
Apparent load power
4
is derived from a separate summation CT an additional direction check with this
4
is connected in the neutral of the set
4
C Connection
SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018
–
Lx
Examples),
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