ABB Relion 670 Series Applications Manual page 509

1MRK 511 401-UEN Rev. K
Insulation aging or deterioration is a time function of temperature, moisture content, and
oxygen content. With modern oil preservation systems, the moisture and oxygen contributions
to insulation deterioration can be minimized, leaving insulation temperature as the controlling
parameter.
Temperature distribution is not uniform in transformers, the part that is operating at the
highest temperature normally undergoes the greatest deterioration. Therefore, in aging
studies it is usual to consider the aging effects produced by the highest (hottest-spot)
temperature. Since many factors influences the cumulative effect of temperature over time
which causes transformer insulation deterioration, it is difficult to predict the useful life of the
insulation in a transformer with great degree of accuracy. However, this function will help in
reducing the accelerated aging of power transformers during overload conditions and thus
maximize the transformer operating life.
18.11.2 Setting guidelines
The parameters for the estimation of transformer insulation life function LOLSPTR are set via
the local HMI or PCM600.
Minimum information about the transformer parameters which are required to decide the
transformer insulation life are:
1. Top oil temperature rise over ambient temperature at rated load
2. Average conductor temperature rise over ambient temperature at rated load
3. Winding hot spot temperature rise over ambient temperature
4. Load losses at rated load
5. No-Load (core) loss
6. Oil flow design (Directed or non-directed)
7. Weight of core and coil assembly
8. Weight of tank and fittings
9. Weight of oil in the tank and cooling equipment (excluding load tap changer, oil expansion
tanks)
For information about 1 to 5, the conditions (load, ambient temperature, tap, etc.) under which
the measurements are made should be known. In order to have more precise calculations, load
loss at rated and tap extremes or all possible tap connection combinations are required.
Operation : Off or On .
TrafoRating : Rated transformer power in MVA.
TrafoType : This setting is used to set the number of phases in the transformer. The options
are:
Three Phase Trafo : The function considers the given transformer as three phase
•
transformer.
Single Phase Trafo : The function considers the given transformer as single phase
•
transformer.
Based on the settings
temperature calculations. Both IEEE and IEC standards defines the transformer parameters
based on three categories of transformer rating.
In the case of three phase transformers:
• If the transformer rating is less than 2.5 MVA, the function considers this as a distribution
transformer.
• If the transformer rating is less than 100 MVA, it is considered as a medium power
transformer.
• If the transformer rating is above 100 MVA, it is considered as a larger power transformer.
Bay control REC670
Application manual
TrafoRating and TrafoType , transformer parameters are selected for
© Copyright 2017 Hitachi Power Grids. All rights reserved
Section 18
Monitoring
GUID-48FC89C4-881E-49F0-AD2A-576D1BDBE9EE v1
GUID-FED52BFB-66A9-46E9-BD11-3FA18DD0FB50 v1
503