GE T60 Instruction Manual page 402

5.6 GROUPED ELEMENTS
INVERSE CURVE C:
The curve for the Volts/Hertz Inverse Curve C shape is derived from the formula:
where: T = Operating Time
5
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 volts/hertz inverse C curves are shown below.
5-268
TDM
---------------------------------------------------- - when
T
=
0.5
V
  Pickup

--- -
 
F
Multiples of volts per hertz pickup
Figure 5–134: VOLTS-PER-HERTZ CURVES, INVERSE CURVE C
T60 Transformer Protection System
V
--- - 
Pickup
F
1
–
5 SETTINGS
(EQ 5.47)
Time
delay
setting
830740A1.CDR
GE Multilin