Nace CP 1 - DC Produced by Rectifying AC; Transformers

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Basic Electricity 1:19

CP 1 – Cathodic Protection Tester Course Manual

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 FORWARD CURRENT