# MINIMUM ENERGY PERFORMANCE (MEPS) ACCORDING TO TCVN 8525: 2015

TCVN 8525: 2015 compiled by the National Technical Standards Committee, proposed by The Directorate for Standards, Metrology, and Quality, announced by the Ministry of Science and Technology to replace TCVN 8525: 2010.

## 1. Scope of application

This standard specifies levels and methods for determining minimum energy efficiency levels applicable to oil-immersed and dry-type three-phase distribution transformers, rated up to 4,000kVA, with rated voltage up to 35kV, working in the power grid with a rated frequency of 50Hz.

For the scope of this standard, a distribution transformer is a transformer having: Rated input voltage less than or equal to 35kV; rated output voltage is less than or equal to 0.4kV, working in a power grid with a rated frequency of 50Hz.

## 2. Minimum Energy Efficiency (MEPS)

Ratio, expressed as a percentage, between the energy output and energy input of a distribution transformer, at a load factor of 50% and a power factor of 1.

Table of minimum energy efficiency (MEPS) values for oil-immersed three-phase distribution transformers:

 kVA MEPS (%) ≤ 25 98,40 31,5/32 98,50 50 98,66 75 98,77 100 98,87 125 98,92 160 98,97 180 99,01 200 99,06 250 99,10 315/320 99,16 400 99,19 500 99,21 560 99,22 630 99,26 750 99,28 800 99,30 1 000 99,32 1 250 99,35 1 500 99,37 1 600 99,39 2 000 99,41 2 500 99,42 3 000 99,44 3 200 99,46 3 500 99,48 4 000 99,50

## 3. Method for determining energy efficiency

The energy efficiency formula is determined as follows:

Explain:

E50%: The transformer's percent efficiency at 50% load factor and 1 power factor;

S: Rated power of the distribution transformer in kVA;

Pk: Load loss of distribution transformer, in kW;

P0: No-load loss of the distribution transformer, in kW.

The result of the E50% calculation shall be corrected to a standard temperature of 75°C according to IEC 60076-1 for oil-immersed transformers and a standard temperature according to the general provisions for the test. of IEC 60076-11 for dry-type transformers.

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