GE 745 Instruction Manual page 189

CHAPTER 5: SETPOINTS
5.6.13.4 Loss of Life Limit

LOSS OF LIFE []
LIMIT
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
• AGING FACTOR LIMIT DELAY: Enter a time delay above which the aging factor must
remain before the element operates.
FIGURE 5–41: Aging factor limit scheme logic
PATH: SETPOINTS S4 ELEMENTS

LOSS OF LIFE LIMIT
FUNCTION: Disabled
LOSS OF LIFE LIMIT
MESSAGE
RLYS (1-8): --------
LOSS OF LIFE LIMIT
MESSAGE
TARGET: Self-Reset
LOSS OF LIFE LIMIT
MESSAGE
PICKUP: 16000 x 10h
LOSS OF LIFE LIMIT
MESSAGE
BLOCK: Disabled
The loss of life limit element computes the total expended life of the transformer, based on
the aging factor and the actual in-service time of the transformer. For example, if the aging
factor is a steady 1.5 over a time period of 10 hours, the transformer will have aged for an
equivalent 1.5 × 10 = 15 hours. The cumulative total number of hours expended is retained
in the relay even when control power is lost. The initial loss of life value, when a relay is first
placed in service, can be programmed under the transformer settings. The element
operates on the cumulative total value, with no time delay. The output of this element
should be used as an alarm only, as users may wish to leave the transformer in service
beyond the theoretical expended life.
INSULATION AGING
 
Range:
Range:
Range:
Range:
Range:
S4 ELEMENTS
LOSS OF LIFE LIMIT
Enabled, Disabled
1 to 8
Self-Reset, Latched, None
0 to 20000 x 10h (a maximum
of 20000 hrs.) in steps of 1
Logc Inpt 1 to 16, Virt Inpt 1 to
16, Output Rly 2 to 8, SelfTest
Rly, Vir Outpt 1 to 5, Disabled
5–93