Nace CP 1, Course Manual

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Basic Electricity 1:19
CP 1 – Cathodic Protection Tester Course Manual
©
NACE International, 2000
02/01/05
Alternating current can be turned into direct current through a
rectifier. This is the function of cathodic protection rectifiers. The
rectified DC still has some ripple in it, however, so it is not the pure
DC that comes from a battery. Figure 1.12 shows a simple rectified
AC.
Figure 1.12 DC Produced by Rectifying AC
Knowledge of alternating current is important in understanding
cathodic protection rectifiers. Some of the more important factors
follow.
Transformers
Transformers may be used to increase or decrease voltage or to
isolate an incoming voltage source from the outgoing voltage. The
transformer has a laminated iron core as illustrated in Figure 1.13
that shows a transformer as part of a cathodic protection rectifier.
There are two sets of windings on the core, the primary and the
secondary. The primary winding is connected to the voltage source.
The secondary winding is connected to the unit to which voltage is
to be supplied.
HALF
CYCLE
ZERO
CURRENT
MAXIMUM FORW ARD CURRENT