Instruction manual –AQ F210 Feeder Protection IED
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CT:s, if possible check the actual ratings from the CT:s
as well, since in some cases the actual CT:s may have
been changed from the original plan for some reason.
Measured current amplitude does not match for one
measured phase or calculated I0 is measured when
there should not be any.
Check wiring connections from injection device or CTs
to the IED. NOTE: If working with CTs which are in
energized system extreme caution should be practiced
when checking connections. Opened CT secondary
circuit may generate dangerously high voltages.
“Buzzing” sound from connector can indicate open
circuit.
Measured current amplitudes are all ok and equal but
the angles are strange.
Phase unbalance protection trips immediately when it
is activated.
Earth fault protection trips immediately when it is
activated.
Phase currents are connected into the measurement
module, but the order or polarity of one or all phases is
incorrect.
Go to Measurement, Phasors and check the current
Phasors diagram.
When all is correctly connected the diagram should
look as below with symmetric feeding:
In following rows few most common cases are
presented
Phase polarity problems are easy to find since the vector diagram points out the opposite polarity in the wrongly
connected phase.
Phase L1 (A) polarity incorrect.
Measurements:
Phase currents
Sequence currents
IL1: 1.00 xIn / 0.00 deg
IL2: 1.00 xIn / 60.00 deg
IL3: 1.00 xIn / 300.00 deg
I1: 0.33 xIn / 180.00 deg
I2: 0.67 xIn / 0.00 deg
I0Calc: 0.67 xIn / 0.00 deg
Resolution:
-
Change wires to opposite in CT module connectors 1
– 2
-
Or from the Transformers, Phase CT scaling select
IL1 polarity to “Invert”.
Phase L2 (B) polarity incorrect.
Measurements:
Phase currents
Sequence currents
IL1: 1.00 xIn / 0.00 deg
IL2: 1.00 xIn / 60.00 deg
IL3: 1.00 xIn / 120.00 deg
I1: 0.33 xIn / 0.00 deg
I2: 0.67 xIn / -60.00 deg
I0Calc: 0.67 xIn / 60.00 deg
Resolution:
-
Change wires to opposite in CT module connectors 3
– 4
-
Or from the Transformers, Phase CT scaling select
IL2 polarity to “Invert”.