The function constantly measures the phase voltage magnitudes as well as the harmonic content of the
monitored signals up to the 31
st
harmonic component. The user can set the alarming limits if the
application so requires.
The monitoring of the measured signals can be selected to be based either on an amplitude ratio or on
the above-mentioned power ratio. The difference is in the calculation formula (as shown below):
Figure. 5.6.5 - 205. THD calculation formulas.
While both of these formulas exist, the power ratio (
THD
P
) is recognized by the IEEE, and the amplitude
ratio (
THD
A
) is recognized by the IEC.
The blocking signal and the setting group selection control the operating characteristics of the function
during normal operation, i.e. the user or user-defined logic can change function parameters while the
function is running. This only applies if the alarming is activated.
The outputs of the function are the START and ALARM ACT signals for the phase voltages ("THDV") as
well as BLOCKED signals. The function uses a total of eight (8) separate setting groups which can be
selected from one common source.
The operational logic consists of the following:
• input magnitude processing
• threshold comparator
• block signal chec
• time delay characteristics
• output processing.
The inputs of the function are the following:
• setting parameters
• digital inputs and logic signals
• measured and pre-processed voltage magnitudes
The function's outputs are START, ALARM and BLOCKED signals 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 output signals. The time stamp resolution is 1 ms. The function
also provides a resettable cumulative counter for the START, ALARM and BLOCKED events.
The following figure presents a simplified function block diagram of the total harmonic distortion
monitor function.
Genera
Generattor Commander
or Commander
Instruction manual
Version: 2.07
386
© Arcteq Relays Ltd
IM00001
Содержание Generator Commander
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