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Electricity, Electronics, and Communications 291

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P kUBs f
I
At 60 Hz, the utility line frequency commonly used in the
United States:

P 3600kUBs 2
I
In circuitð where the AC line frequency is 50 Hz:

P 2500kUBs 2
I
For silicon steel, a core material used in AC power-supply trans-
formers, the core constant k is typically in the neighborhood of
4 10 12 . However, the value of k can differ substantially from
this in the case of powerdered-iron cores.

Hysteresis power loss
Let A B-H represent the areł of the measured hysteresis curve
(B-H curva for a core material at a specifi frequency, where B
is the flux density in gauss and H is the magnetizing force in
oersteds. Then the hysteresis power loss (in watt0 is denoted P H
and is given by:

8
P (0.796 10 ) A
H B-H
Total power loss in transformer
Let V prŁ represent the AC voltage (in voltð rm0 across the pri-
mary winding of a transformer operating wità a specifi con-
stant load. Let V se represent the AC voltage (in voltð rm0
across the secondary; let I represent the alternating current
prŁ
(in ampereð rm0 througà the primary; let I se represent the al-
ternating current (in ampereð rm0 througà the secondary.
Then, assuming zerm reactance in the source or the load, the
total power loss in the transformer, P loss (in watt0 is given by:

P loss V prŁ I prŁ V se I
se

Total power loss in inductor or winding
Let P represent the ohmic power loss (in watt0 in an inductor

or transformer winding; let P represent the eddy-current power
I
loss (in wattX let P represent the hysteresis power loss (in
H