Thytronic DMC3S, Руководство пользователя

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DMC3S - Manual - 08 - 2021
— EAC (Equilibratore Automatico di Carico) [ALB frequency (Automatic Load Balancer)] protection
Preface
EAC (Equilibratore Automatico di Carico) [ALB frequency (Automatic Load Balancer)] protection
processes the following values:
• frequency [Hz];
• derivative of the frequency [Hz/s].
The introduction of the derivative of the frequency is motivated by the need to quickly deal with
situations caused by large power deficits.
The protection has the following regulations:
• Block functions
• Filter functions (measurement means and times)
• EAC1 : 81U, 81O, 81R
• EAC2 : 81U, 81O, 81R
The frequency and frequency derivative values are measured for each phase voltage:
• UL1
• UL2
• UL3
Operating logic
The functions EACx (EAC1, EAC2):
• First maximum/minimum threshold (81O/81U) frequency f>/f<1a [fxa]
• Second maximum/minimum threshold (81O/81U) frequency f>/f<1b [fxb]
• Maximum frequency derivative threshold (81R)
df>1 [dfx/dt]
can be blocked when one of the following thresholds is violated:
• Minimum voltage Ueac<
• Maximum voltage Ueac>
• Maximum unbalance ULS>
the reference value is the difference in absolute value of one of the phase voltages
|UL1|, |UL2|, |UL3 | and the mean of the three (|UL1|+|UL2|+|UL3|)/3
• Maximum frequency difference UG>
the reference value is the difference in absolute value of the phase frequencies max(f1-f2, f2-f3,
f3-f1)
• Maximum variation between consecutive periods UDT>
if T1 and T2 are the amplitudes of two consecutive periods, the reference value is given by their
difference DT=|T1-T2|
• Maximum active return power P->
the reference parameter is the active power input at the bar side, the function can be enabled/
disabled
With EACx enabled (no block) LEDs and relays can be associated for local and remote verification.
Increasing reliability
For more precise measurements and improved insensitivity to transients, the following settings can
be made:
• Number of semi-periods for the average of the frequencies
• Number of semi-periods for calculating the first scale df/dt
• Number of semi-periods for calculating the second scale df/dt
• Number of semi-periods for calculating the third scale df/dt
• Number of averages for calculating the first scale df/dt
• Number of averages for calculating the second scale df/dt
• Number of averages for calculating the third scale df/dt