ABB REG670 - Description of Input Signals

operating mode and is fully functional even with the generator at standstill. It is still
required to have a standard 95% stator earth-fault protection, based on the neutral
point fundamental frequency displacement voltage, operating in parallel with the
100% stator earth-fault protection function.
Requires injection unit REX060 and optional shunt resistor unit REX062 for correct
operation.
7.9.3 Description of input signals
The inputs to the 100% stator earth fault protection function block are as shown in the
table.
Table 133: Description of various inputs
Input signal Description
USU The measured injection voltage. This signal is taken from a pre-processor block, the AI
output. The analog voltage input AI1 is linked to the phase L1 in the pre-processor block
in the Signal Matrix tool.
USI
The measured injection current. This signal is taken from a pre-processor block, the AI
output. In the pre-configured version, the analog voltage input AI2 is linked to the phase
L2 in the pre-processor block in the Signal Matrix tool.
BLOCK
Input to block the function
ZREFSEL The selection of any of the pre-defined reference impedances. The reference impedance
can differ, for example, with the generator breaker open or closed. Therefore, there is a
possibility to change from one set reference impedance to another. Five different
reference impedances are available.
7.9.4 Description of output signals
The outputs of the 100% stator earth fault protection function block are as shown in
the table.
Table 134: Description of various outputs
Output signal
Description
TRIP Trip command signal
START Signal activated, if the calculated fault resistance gets lower than the set level
ALARM Signal activated after a set time delay, if the calculated fault resistance gets lower than
the set alarm level
OPCIRC Signal indicating open stator injection circuit (interruption)
ERROR Error signal which is boolean with values 0 and 1
ERRSTAT Status coded signal giving type of error. See below table
RAVE Measured stator resistance to earth in Ω at an injected frequency (real part of the
complex impedance)
XAVE Measured stator reactance to earth in Ω at the injected frequency (imaginary part of the
complex impedance)
FREQU Measured frequency of the injected voltage
Table continues on next page
Section 7 1MRK502052-UEN B
Impedance protection
294
Technical manual