Section 11 Primary Injection Testing - ABB RET670 Commissioning Manual

1MRK 504 154-UUS B
Section 11
A test with primary current through the protected zone is usually a final check that the current
circuits are correctly connected to the IED protection scheme. It is important to have an
appropriate source, which is able to inject sufficient current in the primary circuit in order to
distinguish between noise and real injected current. Therefore it is recommended that the
injection current should be at least 10% of rated CT primary current.
11.1 Transformer Voltage Control ATCC
11.1.1 Load drop compensation function, LDC
The load drop compensation function can be tested directly with operational currents, in other
words, with the power transformer in service and loaded.
When the system is carrying load there is a difference between the busbar voltage (VB) and the
voltage at the load point (VL). This difference is load dependent and can be compensated by the
ATCC function.
The load current is fed into the ATCC function where parameters corresponding to the line data
for resistance and inductance are set. The voltage drop calculated by the LDC is proportional to
the voltage drop in the system up to the load point.
In the IED, this voltage is subtracted from the measured busbar voltage (VB) and the result,
corresponding to the voltage at the load point (UL) is presented to the ATCC function for the
purposes of voltage regulation. This voltage will be lower (if resistive or inductive load current is
applied) than the Vset voltage and ATCC increases the voltage in order to achieve the correct
system voltage at the load point.
1. Confirm the PST settings for
If the function LDC is set to
2. Open the voltage control display on the LHMI in Main Menu/Control/Commands/
TransformerVoltageControl (ATCC, 90).
Commissioning manual
Primary injection testing
Whenever it becomes necessary to work on primary equipment, it is essential that
all the necessary switching, locking, grounding and safety procedures are observed
and obeyed in a rigid and formalized manner. Operating and testing procedures
should be strictly followed in order to avoid exposure to live equipment.
Rline and Xline .
Zero , this test is omitted.
Section 11
Primary injection testing
IP10812-1 v1
SEMOD65857-3 v3
SEMOD65857-8 v2
SEMOD176327-3 v3
SEMOD176327-117 v5
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