GE 745 TRANSFORMER MANAGEMENT RELAY User Manual

GE Power Management 745 Transformer Management Relay 5-99
5 SETPOINTS 5.10 INVERSE VOLTS-PER-HERTZ CURVES
5
5.10.3 INVERSE CURVE 3
The curve for the inverse curve 3 shape is derived from the formula:
where
T = operate time (seconds)
D = delay setpoint (seconds)
V = fundamental RMS value of voltage (V)
F = frequency of voltage signal (Hz)
Pickup = volts-per-hertz pickup setpoint (V/Hz)
Figure 5–18: INVERSE CURVE 3
T
D
VF
⁄
Pickup
------------------


0.5
1
–
---------------------------------------
=
when
V
F
----
Pickup
>
0.1
1
10
100
1000
10000
1.00 1.20 1.40 1.60 1.80 2.00
Multiples of Voltz/Hertz Pickup
Time
Delay
Setting
ò
3
10
1
0.3
0.1
Time to Trip (seconds)

GE 745 TRANSFORMER MANAGEMENT RELAY Specifications

General

Brand	GE
Model	745 TRANSFORMER MANAGEMENT RELAY
Category	Relays
Language	English