![background image](http://html.mh-extra.com/html/abb/relion-615-series/relion-615-series_technical-manual_2395282.webp)
4.1.5.2
Function block
GUID-68AADF30-9DC7-49D5-8C77-14E774C8D1AF-ANSI V2 EN
Figure 132:
Function block
4.1.5.3
Functionality
The three-phase thermal overload, two time constants, 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
function using a thermal model with two settable time constants. If the temperature rise
continues, 49T 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.
4.1.5.4
Operation principle
The function can be enabled and disabled with the
Operation
setting. The corresponding
parameter values are “Enable” and “Disable”.
The operation of 49T can be described using a module diagram. All the modules in the
diagram are explained in the next sections.
The function uses ambient temperature which can be measured locally or remotely. Local
measurement is done by the protection relay. Remote measurement uses analog GOOSE
to connect
AMB_TEMP
input.
If the quality of remotely measured temperature is invalid or
communication channel fails the function uses ambient temperature set in
Env temperature Set
.
Section 4
1MAC059074-MB A
Protection functions
276
615 series ANSI
Technical Manual
Summary of Contents for Relion 615 series
Page 1: ... RELION PROTECTION AND CONTROL 615 series ANSI Technical Manual ...
Page 2: ......
Page 39: ...Section 17 Glossary 1181 Table of contents 615 series ANSI 33 Technical Manual ...
Page 40: ...34 ...
Page 64: ...58 ...
Page 216: ...210 ...
Page 884: ...878 ...
Page 1038: ...1032 ...
Page 1136: ...1130 ...
Page 1172: ...1166 ...
Page 1180: ...1174 ...
Page 1186: ...1180 ...
Page 1192: ...1186 ...
Page 1193: ...1187 ...
Page 1194: ......
Page 1195: ......