In hopkinson test known as regenerative test two identical machine coupled D.C shunt motor D.C shunt generator temperature rise can be check under rated condition large machine can be tested without drawing much power.
The rating of given on the name plate of a transformer indicates the:Apparent power which it can supply S=V( supplied voltage)*I (load current) active power = v* i*cosφ reactive power = v* i*sinφ
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