ABB REG670 - Page 87

ANSI11000044-1-en.vsd
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Step 1 Step 2 Step 3
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ANSI11000044 V1 EN-US
Figure 18: Different steps at calibration measurements
There are other generator grounding methods and injection alternatives; the injection
can be performed through:
• LV winding of a distribution transformer (DT) located at the stator neutral point
• Open delta winding of a three-phase VT set located at generator terminals
• Open delta winding of a three-phase grounding transformer (GT) located at
generator terminals
Whatever injection alternative is used, the neutral point of the generator must be
accessible in order to connect the calibration resistance (step 2) and short circuit (step
3) during the calibration.
Commissioning
The generator can be in several operating conditions, for example:
• Generator stand still
• Generator running up, not synchronized to the network (circuit breaker open)
• Generator normal operation (circuit breaker closed)
Other operating conditions can be identified.
If a particular stable operating condition of the generator requires a dedicated reference
impedance, it can be defined and saved by the Commissioning tab of ICT.
1MRK 502 073-UUS A Section 7
Calibrating injection based 100% stator earth fault protection
Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062 81
Commissioning manual