GE L90 Instruction Manual page 535

CHAPTER 5: SETTINGS GROUPED ELEMENTS
Figure 5-175: Volts-per-hertz curves, inverse curve B
Inverse curve C
5
The curve for the Volts/Hertz Inverse Curve C shape is derived from the formula:
Eq. 5-39
where
T = Operating Time
TDM = Time Delay Multiplier (delay in sec.)
V = fundamental RMS value of voltage (pu)
F = frequency of voltage signal (pu)
Pickup = volts-per-hertz pickup setpoint (pu)
The figure shows the volts/hertz inverse C curves.
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 5-311