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Electric power as purchased from utility companies
is almost always in the form of alternating or A.C.
current at 60 HZ. This means that the polarity changes
at 60 times per second. Most metal finishing processes
require the polarity to be a constant negative or positive.
Rectifiers convert the A.C. electric power to direct
or D.C. current, which has a constant polarity.
The electric power supplied from the utility company must also be rectified
or adjusted. The voltage is typically too high and the
incoming amperage is typically too low. The rectifier
will amplify or increase the amperage and step-down
or reduce the voltage to levels acceptable for the metal
finishing process.
Controls on the rectifier must be adjusted in order to control the voltage
being applied or the current being drawn. These controls
can be tap switch, powerstat, SCR control, or switchmode
See table 1 for further details. The control used depends
on your application. See table 2 for some examples.
SCR and motorized powerstat units can be controlled by a remote control
box, which can be located near the processing line.
This allows the rectifier to be located in non-corrosive
locations in the plant.
Some processes can be negatively effected by ripple. Ripple is a byproduct
of converting A.C. to D.C. Filter chokes can be installed
into a rectifier, to reduce the amount or ripple to
an acceptable level.
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