Question { 21453 }

How is a 100 MVA transformer cooled?

Answer

THIS TYPE OF HEAVY POWER TRANSFORMER COOLED BY THE FOLLWING
PROCESS.
1. ACTUALLY OIL IS THE MAIN INSULATION MEDIUM BETWEEN CORE
AND TRANSFORMER BODY.
2. OIL CONDUCTS HEAT FROM CORE/ WINDING TO BODY AND
RADIATORS.
3. BY METHOD OF ONAF, HEAT OF TRANSFORMER RADIATED BY
COOLING FANS.
4. IN ADDITION TO THIS WITH OFAF, PROCESS HEAVY PUMPS
CIRCULATES TRANSFORMER OIL TO RADIATORS AND FROM RADIATORS,
HEAT FURTHER , RADIATES AND COOLED FROM AMBIENT
TEMPERATURE.

Question { 20188 }

how to calculate optimum loading for transformer?

Answer

POWER=1.732*VOLTAGE*CURRENT*POWER FACTOR
HERE POWER=2500KVA
VOLTAGE=11 KV
POWER FACOR AS STANDARD=0.85
I=?
I=2500KVA/1.732*11KV*0.85
KV CANCELLED EACH DENOMINATOR AND NUMARATOR,
I=2500/1.732*11*0.85
I=154 AMP (11 KV SIDE)
I=2500 KVA/1.732*415 V*0.85
V CANCELLED EACH DENOMINATOR AND NUMARATOR
I=2500 K/610.963
I=4.091 KA
I=4091 AMP