Installing
During the installation, several checks are performed about both status of the function
and levels of the injected current and voltage. The check of signal levels need the
setting of the UMaxEF according to the value that is selected in REX060: this
parameter is related to the gain of amplifiers of REX060.
A fine measurement of the frequency of the injected signals is also performed to be
able to detect properly interference conditions.
Calibrating
The calibration is based on three measurement steps.
1. The injection is made to the faultless generator and the measured complex
impedance is stored.
2. A known resistance is connected between the generator neutral point (see Figure
18) and earth.
The injection is made to the generator and the measured complex impedance is
stored.
3. The generator neutral point (see Figure 18) is directly short-circuited to the earth.
The injection is made to the generator and the measured complex impedance is
stored.
The sequence of the calibration steps is driven by ICT and it is shown in the figure
below. The connection of the calibration resistance and short circuit is shown here for
the case with injection in the generator neutral point through the neutral point VT and
generator grounding through primary resistor.
Section 7 1MRK 502 073-UUS A
Calibrating injection based 100% stator earth fault protection
80 Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062
Commissioning manual
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