CHAPTER 5: SETTINGS GROUPED ELEMENTS
T35 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL 5-205
5
5.7.3.3 Instantaneous differential
SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) TRANSFORMER INSTANTANEOUS DIFFERENTIAL
The instantaneous differential element acts as an instantaneous overcurrent element responding to the measured
differential current magnitude (filtered fundamental frequency component) and applying a user-selectable pickup
threshold. Set the pickup threshold greater than the maximum spurious differential current that can be encountered under
non-internal fault conditions (typically magnetizing inrush current or an external fault with extremely severe CT saturation).
Figure 5-104: Instantaneous differential logic
5.7.3.4 Hottest-spot temperature
SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) TRANSFORMER HOTTEST-SPOT TEMPERATURE
The Hottest-Spot Temperature element provides a mechanism to detect abnormal winding hottest-spot temperatures
inside the transformer. It can be set to alarm or trip in cases where the computed hottest-spot temperature is above the
pickup threshold for a user-specified time (considered as transformer overheating).
INSTANTANEOUS
DIFFERENTIAL
INST DIFFERENTIAL
FUNCTION: Disabled
Range: Disabled, Enabled
INST DIFFERENTIAL
PICKUP: 8.000 pu
Range: 2.000 to 30.000 pu in steps of 0.001
INST DIFF BLOCK:
Off
Range: FlexLogic operand
INST DIFFERENTIAL
TARGET: Self-reset
Range: Self-reset, Latched, Disabled
INST DIFFERENTIAL
EVENTS: Disabled
Range: Disabled, Enabled
HOTTEST-SPOT
TEMPERATURE
XFMR HST FUNCTION:
Disabled
Range: Disabled, Enabled
XFMR HST PICKUP:
140°C
Range: 50 to 300°C in steps of 1
XFMR HST DELAY:
1 min.
Range: 0 to 30000 min. in steps of 1
XFMR HST BLOCK:
Off
Range: FlexLogic operand
XFMR HST TARGET:
Self-Reset
Range: Self-reset, Latched, Disabled
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