GE G60 UR Series, Instruction Manual

Page: 319 / 634

GE Multilin G60 Generator Protection System 5-187
5 SETTINGS 5.6 GROUPED ELEMENTS
5
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
VOLTS/HZ T-RESET
seconds. The V/Hz element
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: T(sec.) = TD Multiplier. For example, setting the TD Multiplier set to 20 means a time delay of 20 sec-
onds to operate, when above the Volts/Hz pickup setting. Instantaneous operation can be obtained the same way by
setting the TD Multiplier to “0”.
• INVERSE CURVE A:
The curve for the Volts/Hertz Inverse Curve A shape is
derived from the formula:
(EQ 5.29)
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)
• INVERSE CURVE B:
The curve for the Volts/Hertz Inverse Curve B shape is
derived from the formula:
(EQ 5.30)
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)
• INVERSE CURVE C:
The curve for the Volts/Hertz Inverse Curve C shape is
derived from the formula:
(EQ 5.31)
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)
T
TDM
V
F
----
⎝ ⎠
⎛ ⎞
Pickup
⁄
2
1
–
-------------------------------------------------
when
V
F
----
Pickup
>
=
Multiples of volts per hertz pickup
Time
to
trip
(in
seconds)
Time
delay
setting
830738A1.CDR
T
TDM
V
F
----
⎝ ⎠
⎛ ⎞
Pickup
⁄
1
–
----------------------------------------------
when
V
F
----
Pickup
>
=
Time
to
trip
(in
seconds)
Multiples of volts per hertz pickup
830739A1.CDR
Time
delay
setting
T
TDM
V
F
----
⎝ ⎠
⎛ ⎞
Pickup
⁄
0.5
1
–
----------------------------------------------------- when
V
F
---- Pickup
>
=
Time
to
trip
(in
seconds)
Multiples of volts per hertz pickup
830740A1.CDR
Time
delay
setting