CHAPTER 4: SETPOINTS PROTECTION
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL 4–219
Figure 4-80: Volts-Per-Hertz Curves for Inverse Curve A
Inverse Curve B:
The curve for the Volts/Hertz Inverse Curve B shape is derived from the formula:
where: T = Operating Time
TDM = Time Delay Multiplier (delay in seconds)
V = fundamental RMS value of voltage (pu)
F = frequency of voltage signal (pu)
Pickup = volts-per-hertz pickup setpoint (pu)
The Volts/Hertz inverse B curves are shown below.
Pickup
F
V
when
Pickup
)
V
TDM
T !
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