GE T60 Instruction Manual page 405

5 SETTINGS
• Source Transfer Schemes: In the event of an undervoltage, a transfer signal may be generated to transfer a load
from its normal source to a standby or emergency power source.
The undervoltage elements can be programmed to have a definite time delay characteristic. The definite time curve oper-
ates when the voltage drops below the pickup level for a specified period of time. The time delay is adjustable from 0 to
600.00 seconds in steps of 0.01. The undervoltage elements can also be programmed to have an inverse time delay char-
acteristic.
The undervoltage delay setting defines the family of curves shown below.
where: T = operating time
D = undervoltage delay setting (D = 0.00 operates instantaneously)
V = secondary voltage applied to the relay
V = pickup level
pickup
At 0% of pickup, the operating time equals the UNDERVOLTAGE DELAY setting.
NOTE
GE Multilin
D
T --------------------------------- -
=

1 ------------------
–

V
pickup
% of voltage pickup
Figure 5–124: INVERSE TIME UNDERVOLTAGE CURVES
T60 Transformer Protection System
V


842788A1.CDR
5.6 GROUPED ELEMENTS
(EQ 5.45)
5-259
5