Figure 14-2. A small transformer inside the equipment
lowers the line voltage to 24 V for the control circuit.
Transformers are frequently used inside electronic equipment.
HOW THE TRANSFORMER
WORKS
A clear understanding of how transformers work is
nectssary in order to wire them properly in an electrical
system. Understanding input and output current and
grounding are particularly troublesome. A dual-voltage
transformer can be ruined when power is applied, if the
connections are made improperly.
An important property of electricity is that a magnetic
field is produced around a wire in which electrical
current is flowing, Figure 14-3. The more current that
flows, the stronger is the magnetic field. An even
stronger magnetic field can be produced by winding the
wire into a coil. Now the magnetic fields of adjacent
wires add together to form one strong magnetic field.
The electrical current flowing in a transformer is alternating
current. The current flows first in one direction,
stops, then reverses and flows in the other direc