Functions
2.8 Overexcit. Protection (Volt/Hertz) 24
SIPROTEC, 7RW80, Manual
C53000-G1140-C233-1, Release date 10.2010
104
The following figure shows the logic diagram for overexcitation protection. The counter can be reset to zero by
means of a blocking input or a reset input.
Figure 2-29 Logic diagram of the Overecxitation protection
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 con-
figuration 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 in-
duction.
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
N
) as specified by the manufacturer of the object to be protected.
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.
To Next Page
Loading...
Need help?
General