Table. 5.4.21 - 195. Register content.
Date and
time
Event
Fault type
Pre-
trigger
current
Fault
current
U1
Voltage
Current
pick-up
Pre-
fault
current
Trip time
remaining
Used
SG
dd.mm.yyyy
hh:mm:ss.mss
Event
name
L1-E…L1-L2-L3
Start/Trip
-20ms
current
Start/
Trip
current
Positive
sequence
voltage
Pick-up
current
level
Start
-200ms
current
0
ms...1800s
Setting
group
1...8
active
5.4.22 Volts-per-hertz overexcitation protection (V/Hz>; 24)
Generators, transformers, and motors have their own, specific volts-per-hertz ratios under which these
machines are expected to operate. Exceeding the V/Hz ratio results in machine overexcitation which
causes iron core saturation in generators and transformers. This causes a breakdown of the insulation
in the core's interlamination due to excessive voltage and eddy current heating. Additionally, stray flux
is induced into non-laminated components which are not designed to carry flux-caused currents. In
generators overexcitation typically occurs if the V/Hz ratio goes five percent above the nominal V/Hz
ratio, with any possible damage happening within seconds. The most common situation for
overexcitation is when a machine is off-line prior to synchronization.
The figure below shows how the pick-up settings and the measured frequency affect the pick-up level
of the volts-per-hertz protection function.
Figure. 5.4.22 - 117. Effect of pick-up settings and the measured frequency to the overvoltage function's pick-up level.
Volts-per-hertz protection is based on the ratio between the maximum phase-to-phase voltage and the
measured system frequency. 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.
Genera
Generattor Commander
or Commander
Instruction manual
Version: 2.07
228
© Arcteq Relays Ltd
IM00001
Содержание Generator Commander
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