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[logikdiagramm-des-uebereregungsschutzes-020827-ho, 1, en_US]
Figure 2-29
2.8.2
Setting Notes
General
Overecxitation Protection is only in effect and accessible if address 143 24 V/f is set to Enabled during
configuration of protective functions. If the function is not required Disabled is set. Under address 4301 FCT
24 V/f the function can be turned ON or OFF.
Overexcitation protection measures the voltage/frequency quotient which is proportional to the induction B.
The protection must intervene when the limit value for the protected object (e.g. unit transformer) is
exceeded. The transformer is for example endangered if the power station block is switched off at full-load
operation and the voltage regulator does not respond fast enough or not at all to avoid related voltage
increase.
Similarly a decrease in frequency (speed), e.g. in island systems, can lead to an inadmissible increase in induc-
tion.
In this way the V/f protection monitors the correct functioning both of the voltage regulator and of the speed
regulation, in all operating states.
Independent Elements
The limit-value setting at address 4302 24-1 PICKUP is based on the induction limit value relation to the
nominal induction (B/B
A pickup message is transmitted as soon as the induction limit value V/f at address 4302 is exceeded. A
warning message is transmitted after expiry of the corresponding 4303 24-1 DELAY time delay.
The 4304 24-2 PICKUP, 4305 24-2 DELAY trip element characteristic serves to rapidly switch off particu-
larly strong overexcitations.
The time set for this purpose is an additional time delay which does not include the operating time (measuring
time, drop-out time).
SIPROTEC 4, 7RW80, Manual
C53000-G1140-C233-4, Edition 07.2018
Logic diagram of the Overecxitation protection
) as specified by the manufacturer of the object to be protected.
N
2.8 24 Overexcit. Protection (Volt/Hertz)
Functions
93
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