17-01-2014, 12:20 PM
TRANSFORMERS
TRANSFORMERS.ppt (Size: 1.81 MB / Downloads: 68)
HISTORY
1831 – Michael Faraday invented the Induction Ring.
1881 – Lucien Gaulard and John Gibbs exhibited a device called secondary generator.
1885 – William Stanley developed the fist commercially used practical device while working for Westinghouse Electric Company in US.
LOSSES
Transformers have losses and these losses must come into consideration.
Copper losses (I^2 R)
Leakage Flux losses
Core losses
Eddy currents
Hysteresis losses
EFFICIENCY
Efficiency (η) is the ratio of the power out to the power in of a transformer.
η in an Ideal transformer, no power losses
PIN = VPIP cos θP
POUT = VSIS cos θS
PIN = POUT = VPIP cos θP = VSIS cos θS
SOUT = SIN = VPIP = VSIS
ηIdeal = 100%