Transformers

Transformer

Electromagnetic device that changes AC from low to high or high to low without losing lots of energy

Transformer Law

the emf induced in the secondary coil is to the emf in the primary coil, as the number of turns in the secondary coil is to the number of turns in the primary coil

Air Core

two insulted coils lying side by side

Open Core

More efficient than the air core transformer it has an iron core inserted into the coil of wire 

Closed transformer 

provides continuous path for magnetic flux

has a laminated core that is made up of layers of metal plates 

shelly transformer 

most advaned and efficient must be heavily insulated 

How does transformer lose power

in the form of heat

How much percent do transformers lose

5 percent

Copper loss

pertain to the loss of electrical power due to the resistance of the coils

Eddy current loss

swirling currents in the core itself by induction

minimized by laminated silicon steel plates

Hysteresis

Power loss occurs as a result of the changing magnetic fields by the AC in the windings

Reduced by the laminated steel core

Autotransformer

Varies input voltage to transformer to control output

What principle do Autotransformer use

Self induction

Choke oil

Operates on the principle of self inductance and requires AC

Rheostat

Variable resistor that is designed to regulate filament current

Transformer formula for volts

Primary voltage x secondary turns/primary turns

Transformer formula for amperage

Primary amperage x (primary turns/ secondary turns)

if the voltage is stepped up what happens to the current in the secondary side of the transformer

decreases

When the radiographer select kVp on control panel what device is adjusted 

autotransformer