GE 845 - Page 372

4–244 845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
MONITORING CHAPTER 4: SETPOINTS
Winding Hottest
HOTTEST-SPOT TEMPERATURE
The Hottest-Spot Temperature element provides the mechanism for detecting the hottest-
spot winding temperatures inside the transformer. It can be set to alarm or trip in cases
where the hottest-spot temperature (as computed by the relay) is above the PKP threshold
for the specified time, this is considered an overheated transformer.
Path: Setpoints > Monitoring > Transformer > Hottest-Spot Temperature
FUNCTION
Range: Disabled, Alarm, Latched Alarm, Configurable
Default: Disabled
PICKUP
Range: 50 to 300 in steps of 1 degree (in degrees
° F or °C)
Default: 140
Enter the hottest-spot temperature required for operation of the element. This setting
must be defined based on the maximum permissible hottest-spot temperature under
emergency transformer loading conditions, and the maximum ambient temperature.
PICKUP DELAY
Range: 0 to 60000 min in steps of 1 min
Default: 1 min
This setting is used to select a pickup time delay that is used to delay the operation of
the protection.
OUTPUT RELAY 1 (X)
Range: Do Not Operate, Operate
Default: Do Not Operate
The menu includes a list of available output relays to be set for operation or no
operation upon protection operation.
BLOCK
Range: Off, Any FlexLogic operand
Default: Off
EVENTS
Range: Enabled, Disabled
Default: Enabled
The selection of the
Enabled setting enables the events function.
TARGETS
Range: Disabled, Self-reset, Latched
Default: Self-reset
The selection of the
Self-reset or Latched settings enables the target messages of the
function.
Figure 4-94: Hottest-Spot Logic diagram