GE G30 Instruction Manual page 342

5.6 GROUPED ELEMENTS
The element has a linear reset characteristic. The reset time can be programmed to match the cooling characteristics of the
protected equipment. The element will fully reset from the trip threshold in
5
may be used as an instantaneous element with no intentional time delay or as a Definite or Inverse timed element.
The characteristics of the inverse curves are shown below.
DEFINITE TIME:
For the definite time curve, T(sec.) = TD multiplier. For example, setting the TD multiplier to 20 results a time delay of 20
seconds to operate when above the Volts/Hz pickup setting. Instantaneous operation can be obtained the same way by set-
ting the TD multiplier to "0".
INVERSE CURVE A:
The curve for the volts/hertz inverse curve A 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)
5-202
Figure 5–87: VOLTS PER HERTZ SCHEME LOGIC
TDM
T ------------------------------------------------ - when
=
2
V
  Pickup
--- - ⁄
1
–
 
F
G30 Generator Protection System
seconds. The V/Hz element
VOLTS/HZ T-RESET
V
--- - > Pickup
F
5 SETTINGS
(EQ 5.49)
GE Multilin