Asinglephase transformer has the following
nameplate data:
rating 150kva
primaryvoltage 7.2kv
secondaryvoltage 600v
frequency 60hz
whenoperating at rated load (full load) the
following lossesoccur:
hysterisisloss 550 w
eddy currentloss 400 w
total copperlosses 1800 w (primary + secondary)
thetransformer is to be used on a 50 hz system with
the restrictionthat it is to
maintain thesame maximum core flux density and the
same total losses. thiswill
result in thesame full load operating temperature.
determine:
(i) the newprimary and secondary voltage rating at
50 hz;
(ii) the newkva rating of the transformer of the 50
hz.

An external consultant recommends that a plant installs a bank of capacitors for power factor correction. this will reduce the peak electrical demand charges by an average of 93 kw every month. the plant current pays $13 per kw in peak demand charges. the capacitor bank will include 223 kw of fixed capacitors, and 183 of variable capacitors. the fixed capacitors cost $59 per kw, and the variable capacitors will cost $65 per kw. the consultant charges 21% of the equipment costs to install the capacitors. because this project will reduce the demand for the electric utility, they are prepared to provide a one-time rebate of $42 per kw of reduced demand. what is the simple payback period for this project (in years)?