Arcteq Generator Commander, Instruction Manual

Page: 216 / 561

Figure. 5.4.19 - 112. Underexcitation protection with impedance measurement.
The underexcitation function uses a total of eight (8) separate setting groups which can be selected
from one common source.
The function can operate on instant or time-delayed mode (DT).
The operational logic consists of the following:
• input magnitude processing
• threshold comparator
• block signal check
• time delay characteristics
• output processing.
The inputs for the function are the following:
• operating mode selections
• setting parameters
• digital inputs and logic signals
• measured and pre-processed impedance magnitudes.
he function's outputs are START, TRIP and BLOCKED signals which can be used for direct I/O
controlling and user logic programming. The function generates general time-stamped ON/OFF events
to the common event buffer from each of the three (3) output signals. In the instant operating mode the
function outputs START and TRIP events simultaneously with an equivalent time stamp. The time stamp
resolution is 1 ms. The function also provides a resettable cumulative counter for the START, TRIP and
BLOCKED events.
Measured input
The function block uses phase-to-phase impedance values, phase-to-phase impedance values or
positive sequence impedance values. A -20ms averaged value used for pre-fault data registering.
Genera Generattor Commander or Commander
Instruction manual
Version: 2.07
214 © Arcteq Relays Ltd
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