4.1.5.10 Technical revision history
Table 236: T1PTTR Technical revision history
Technical revision Change
C Removed the
Sensor available
setting parameter
D Added the AMB_TEMP input
4.1.6 Three-phase thermal overload protection for power
transformers, two time constants T2PTTR
4.1.6.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Three-phase thermal overload
protection for power transformers, two
time constants
T2PTTR 3Ith>T 49T
4.1.6.2 Function block
GUID-68AADF30-9DC7-49D5-8C77-14E774C8D1AF V2 EN
Figure 117: Function block
4.1.6.3 Functionality
The three-phase thermal overload, two time constant protection function T2PTTR
protects the transformer mainly from short-time overloads. The transformer is
protected from long-time overloads with the oil temperature detector included in its
equipment.
The alarm signal gives an early warning to allow the operators to take action before
the transformer trips. The early warning is based on the three-phase current
measuring function using a thermal model with two settable time constants. If the
temperature rise continues, T2PTTR operates based on the thermal model of the
transformer.
After a thermal overload operation, the re-energizing of the transformer is inhibited
during the transformer cooling time. The transformer cooling is estimated with a
thermal model.
Section 4 1YHT530004D05 D
Protection functions
232 615 series
Technical Manual
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