GE TRANSFORMER MANAGEMENT RELAY 745 Instruction Manual page 131

5 SETPOINTS
b) HOTTEST SPOT LIMIT
PATH: SETPOINTS S4 ELEMENTS
HOTTEST-SPOT LIMIT
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The Hottest-Spot Limit element provides a means of detecting an abnormal hot spot inside the transformer. The element
operates on the computed hottest-spot value. The Hottest-spot temperature will revert to 0°C for 1 minute if the power sup-
ply to the relay is interrupted.
• HOTTEST SPOT LIMIT PICKUP: Enter the Hottest-spot temperature required for operation of the element. This set-
ting should be a few degrees above the maximum permissible hottest-spot temperature under emergency loading con-
dition and maximum ambient temperature.
• HOTTEST SPOT LIMIT DELAY: Enter a time delay above which the hottest-spot temperature must remain before the
element operates.
GE Multilin
Courtesy of NationalSwitchgear.com
INSULATION AGING HOTTEST-SPOT LIMIT
ð
HOTTEST-SPOT LIMIT
ENTER
FUNCTION: Disabled
ESCAPE
HOTTEST-SPOT LIMIT
ESCAPE
TARGET: Self-Reset
MESSAGE
HOTTEST-SPOT LIMIT
ESCAPE
PICKUP: 150°C
MESSAGE
HOTTEST-SPOT LIMIT
ESCAPE
DELAY: 10 min.
MESSAGE
HOTTEST-SPOT LIMIT
ESCAPE
BLOCK: Disabled
MESSAGE
Figure 5–36: HOTTEST-SPOT LIMIT SCHEME LOGIC
745 Transformer Management Relay
5.6 S4 ELEMENTS
Range: Enabled, Disabled
Range: Self-Reset, Latched, None
Range: 50 to 300°C in steps of 1
Range: 0 to 60000 min. in steps of 1
Range: Logc Inpt 1 to 16, Virt Inpt 1 to 16, Output Rly 2 to
8, SelfTest Rly, Vir Outpt 1 to 5, Disabled
5
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