Estimation Of Transformer Insulation Life Lolsptr - ABB REC670 Applications Manual

Section 17
Monitoring
17.11
17.11.1
506
The setting tAddToTime is a user settable time parameter in hours.

Estimation of transformer insulation life LOLSPTR

Function description
Estimation of transformer winding
insulation life
Application
A typical power transformer is composed of:
• Laminated steel core with copper or aluminium windings
• Solid refined paper insulation
• Highly refined mineral oil as insulating and cooling medium for the entire
transformer
The oil is cooled by a separate cooling system using air or water. The core,
windings and insulation have specific thermal capabilities.
Losses in the winding and core can cause temperature rises in the transformer,
which is transferred to the insulating oil. Failure to limit these temperature rises to
the thermal capability of the insulation and core materials can cause premature
failure of the transformer.
A transformer is rated at the power output. It can continuously deliver at rated
voltage and frequency without exceeding the specified temperature limit. This
temperature rise is based on thermal limitations of the core, winding and insulation.
Therefore, transformer MVA rating is based on maximum allowable temperature of
the insulation. Design standards express temperature limits for transformers
exceeds ambient temperature. Use of ambient temperature as a base ensures that a
transformer has adequate thermal capacity and independent of daily environmental
conditions.
Transformers in the power system are designed to withstand certain overload
conditions. The permissible transformer load level is highly depends on the
transformer cooling system. Both IEEE and IEC standards have established
transformer thermal model for all cooling system types and described formulae for
transformer temperature calculation.
IEC 61850 IEC 60617
identification identification
LOLSPTR
3Ihp>T
1MRK 511 401-UEN A
GUID-D9D1F036-EC75-40A8-860F-192CF1F6F759 v1
GUID-A3D72F4B-9567-4DF0-867A-9F657A7E9291 v1
ANSI/IEEE C37.2
device number
26/49HS
GUID-7F37B3D6-C98E-4780-AB5B-12780566FFA2 v1
Bay control REC670 2.2 IEC
Application manual