Generators, motors, transformers

Advantages to alternating current

1. Needed to operate transformers. 2. Less power loss.

2 main components of a generator

1. strong electromagnet 2. Coil of rotating wire

RPM of anode

3400 rotation speed of anode (rpm)

Major KVP selector

Adjust by 10

Minor KVP selector

Adjust by 2

Current of Transformers

All run on alternating current. Changes voltage and amperage

Synchronous motor

Built like AC generator Current is fed into the armature of an AC motor causing it to move

Hysteresis

Changing magnetic fields in the core.

Closed core transformer

Circular or Square in shape Laminated core, for reducing heat and combat Eddy currents

Armature

Conductive piece of wire. Rotate to induce.

Single phase generator

Consist of a single coil of wire (Armmature) rotating through a single stationary magnetic field

Primary circuit side

Contains the power source

Motors

Convert electrical energy to mechanical

Generator

Convert mechanical energy into electrical energy. Used to get electrical power.

Secondary circuit side

Current is induced to flow in the secondary circuit

Types of transformers

Determine by the specific use and the space requirements

Direction of current flow in a generator is governed by?

Direction of armature

Power loss due to

Eddy currents

Electricity in the United States

Electricity supply to buildings in United States is 220 V, 60 Hz (60 cycles per second - AC which changes its direction of motion 120 times per second) Always alternates twice

Commuter ring

Ensure that current flows in only One Direction through the external circuit

Hertz (Hz)

Frequency: number of cycles per second 1 Hz= 1 cycle/ second

What is needed to operate transformers in x-ray circuit?

Generator

Three phase transformers

High tension transformers, used in three phase equipment

Right hand rule

Index finger: magnetic field Middle finger: direction of current Thumb: direction of movement of conductive wire

Amperage & turns ratio

Inversely proportional IP = NS IS = NP

Shell - type transformer

Largest, most powerful type of transformer Laminated core to combat eddy currents

Air core transformer

Less efficient

Open core transformer

Less efficient

Step down transformer(closed core)

Less turns on secondary side, more turns on the primary Decreases voltage, increases amperage Steps down voltage 8-12 V Feeds into cathode for thermionic emission (more electrons at the filament) Operates on mutual induction

Root means square (RMS)

Looking at heat Similar to quality factors. RMS value compares a given AC to a set amount of DC. These direct current flows continuously in one direction.

Step up transformer (closed core)

More turns on secondary side, less turns on primary. Increase voltage, decrease amperage Operates on mutual induction Typical turns ratio is 700:1 Increase voltage 500 to 1000 V Feeds into both anode and cathode

Voltage & turns ratio

Number of coils in primary/secondary=directly proportional VS = NS VP = NP

Slip rings

Only in alternating current generator. Feed the current.

Electromagnetic induction

Operates transformers, generators, & motors in x-ray machines

Crest

Points of high amplitude

Trough

Points of low amplitude

Electromagnet (generator)

Provide magnetic field

Brushes (generator)

Push power through current

Auto transformer

Single coil wrapped around a ferromagnetic bar Variable transformer KVP selector Source of voltage, sends voltage to step up transformer Sends amperage to step down transformer Operates on the principle of self induction

Alternating current cycles are best represented by?

Sinusoidal (sine) curve

Eddy currents

Small currents found in core and in the shell and closed core transformers. Bad- create heat = less function/contribute to inefficiency

Motor

Starts with current, and then make something move

Generator

Starts with something moving and then make current

Transformer, efficiency

Transformers are 95% efficient

How many types of AC motors?

Two

Laminated core

Used in closed core transformers and shell type transformers Makes transformer more efficient. Reduce heat by stopping current flow.

How to reduce heat

Using materials with low magnetic retentivity decreases the loss of power due to hysteresis (iron, silicone).

Electrical power in our homes

Utilizes 120 or 240 Volts

Volts

Voltage - potential difference

Induction motor

What rotates the anode in the x-ray tube Contains electromagnets, stators, rotor Rotor: iron core with copper bars, rotate the anode Stators: outside envelope

Parts of Direct current generator

armature, electromagnet, **commutator ring, brushes Still a functioning, alternating current, but commuter rings stabilizes current to ensure direct feed out of generator to circuit

Parts of Alternating current (AC) generator

electromagnet, **slip rings, brushes, armature