Technical Data; Three-Phase Thermal Overload Protection For Power Transformers, Two Time Constants 49T; Identification; Function Block - ABB RELION 620 Series Technical Manual

Section 4
Protection functions
4.5.1.9
4.5.2
4.5.2.1
4.5.2.2
4.5.2.3
380

Technical data

Table 317: 49F Technical data
Characteristic
Operation accuracy
1)
Trip time accuracy
1) Overload current > 1.2 × Trip level temperature
Three-phase thermal overload protection for power
transformers, two time constants 49T

Identification

Function description
Three-phase thermal overload
protection for power transformers, two
time constants

Function block

GUID-68AADF30-9DC7-49D5-8C77-14E774C8D1AF-ANSI V2 EN
Figure 174: Function block

Functionality

The three-phase thermal overload, two time constant protection function 49T 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
Value
Depending on the frequency of the measured
current: f ±2 Hz
n
Current measurement: ±1.5% of the set value or
±0.002 × I (at currents in the range of 0.01...4.00 ×
n
I )
n
±2.0% of the theoretical value or ±0.50 s
IEC 61850 IEC 60617
identification identification
T2PTTR 3Ith>T
1MAC504801-IB E
ANSI/IEEE C37.2
device number
49T
620 series ANSI
Technical Manual