GE T60, Instruction Manual

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GE Multilin T60 Transformer Protection System 5-259
5 SETTINGS 5.6 GROUPED ELEMENTS
5
• 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.
(EQ 5.45)
where: T = operating time
D = undervoltage delay setting ( D = 0.00 operates instantaneously)
V = secondary voltage applied to the relay
V
pickup
= pickup level
Figure 5–124: INVERSE TIME UNDERVOLTAGE CURVES
At 0% of pickup, the operating time equals the UNDERVOLTAGE DELAY setting.
T
D
1
V
V
pickup
------------------
–
 
 
----------------------------------
=
842788A1.CDR
% of voltage pickup
T
ime
(seconds)
NOTE