Section 12 Primary Injection Testing; Transformer Voltage Control Atcc; Load Drop Compensation Function, Ldc - ABB Relion 670 Series Commissioning Manual

1MRK 511 403-UEN E
Section 12
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.
12.1

Transformer Voltage Control ATCC

12.1.1

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 (UB) and
the voltage at the load point (UL). 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 (UB) 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 Uset 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).
Bay control REC670
Commissioning manual
Primary injection testing
Whenever it becomes necessary to work on primary equipment, it is essential
that all the necessary switching, locking, earthing 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.
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Section 12
Primary injection testing
IP10812-1 v1
SEMOD65857-3 v3
SEMOD65857-8 v2
SEMOD176327-3 v3
SEMOD176327-117 v5
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