# CURRENT RATING OF DISTRIBUTION TRANSFORMER

## WHAT IS DISTRIBUTION TRANSFORMER–

Distribution transformers are electrical equipment that steps down higher electrical voltage(11kv, 6.6 kV) supply into lower voltage supply up to 220 v. These transformers are used to steps down the electrical voltage range 220 volts, and By using these output voltages we use it to run in our house equipment, shops, and low tension(LT) supply industries.

Distribution Transformer Current Calculator

Through this calculator Transformer Current Calculator, we can calculate the current rating of the distribution transformer.

## RATING OF DISTRIBUTION TRANSFORMER–

what is the Distribution transformer rating being used in India and US are as follow

we can categorize distribution transformers into three categories.

Low rating distribution transformers-10 kva, 25 kva, 63 kva, 100 kva,

Medium distribution transformer-250 kva 400 kva 630 kva

High rating distribuion transformer – 1 mva , 2.5 mva ,5 mva ,10 mva

#### HOW TO CALCULATE RATING OF DISTRIBUTION TRANSFORMER–

1-WHAT IS THE RATING OF A SINGLE-PHASE TRANSFORMER

AS WE e know in case of single-phase transformer
P = V x I.

P= POWER(VA) v=voltage, i =current

##### Rating of a single phase transformer in kVA

kVA= (V x I) / 1000

Rating of a Three Phase Transformer:
as we know in three-phase we calculate the power of the transformer
by using this formula,
P = √3. V x I

Rating of a Three-phase transformer in kVA unit

KVA = (√3. V x I ) /1000,

#### calculation of current rating of distribution transformer–

If KVA rating of a distribution transformer is known then how to calculate the current rating –

For 100kva transformer maximum current capacity of distribution transformer on LT(440 v) side would be
100kva=√3.x 420v x I
I= 100×1000 / 1.732X420v= 137 amp (appox)

SHORT CUT FOR CALCULATION OF DISTRIBUTION TRANSFORMER’S CURRENT RATING-
low rating t/f contain -10 kva, 25 kva, 63 kva, 100 kva
medium level t/f-250 kva 400 kva 630 kva
high rating t/f- 1 mva , 5 mva ,10 mva

all above distribution t/f are used on voltage-11 kv /440 v

Its current rating on lt side(440 v side) can be found  by 1.31* t/f rating= current rating

ex- current rating of 250 t/f- 1.31*250=325 amp

hence rating of t/f on l t side is 325 amp.

similarly rating on 11 kv side can be calculated by =current on l t side/25

ex– for 250 kva transformer=325/25=13 amp.

The same result can be obtained from Transformer Current Calculator

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Distribution Transformer: Construction | Type | Rating