Physics Test 3

All transformers always and only regulate

Voltage

Voltage and current are ________ proportional on transformers

inversely

All transformers ______________

work on the principle of Faraday’s law and opperate on AC

Autotransformers

Where the tech has the oppertunity to select volts major, volts minor, mA

Autotransformers operate on

the theory of self induction

What are the components of the theory of self induction?

There is a primary side=NP, on the secondary side we “tap off” of different wires/selectors - “secondary windings“ = NS

Step up transformer

Also known as high voltage transformer and tension transformer. Operates on the theory of mutual induction

What are the components of the theory of mutual induction?

There are seperate primary(NP) and secondary(NS) cores, where we go from voltage(primary) to kilovoltage(secondary)

Since there are more windings on the secondary side, voltage will _____

increase

Number of windings and change in voltage across transformer are _______ proportional

directly

If there is 1 winding on primary and 1000 windings on secondary, for every volt on primary how many volts are on secondary?

1000

Turn’s Ratio

Ns/Np

Helpful equation related to turn’s ratio

Ns/Np=Vs/Vp=Ip/Is

Np

number of windings on primary side

Ns

number of windings on secondary side

Vp

volts primary

Vs

volts secondary

Faraday’s law must operate on

AC

Step down transformer

Also known as filament transformer and is measured in amps, uses fillament current, heats up fillament, causes voltage to decrease because Ns<Np

Ip

current/amps primary

Is

current/amps secondary

Faraday’s law only opperates ___ and is all about ____

on AC, EMF

First rule of Faraday’s law

a wire will emit EMF and the right hand rule falls under this

Right hand rule

Place right hand around a wire that has current with the thumb in the direction of the current. Your fingers will point in the direction of the EMF given off by the wire.

Current and electrons travel in _________ directions in the wire

opposite

Faraday’s second law

The wire with current will emit EMF around the wire. If we take that wire and wrap it around a metal core the EMF from the wire will create EMF (magnitism) in the core.

Faraday’s third law

If we take a secondary core and place it next to the primary core the EMF in the secondary core

Faraday’s fourth law

If we wrap a wire around the secondary core, the EMF from the secondary core will now create current in the secondary wire.

Tube current is measured in _______ while fillament current is measured in ____________

mA, amps

The three types of transformers, how step up and step down are constructed

open core, closed core, and shell type

Open core

least efficient core type

Closed core

more efficient core type, captures more EMF on the secondary core

Shell type

most efficient core type, secondary core or Ns captures more EMF emitted by Np

Transformers increase volts 

on the step up with mutual induction

Transformers decrease volts

on the step down with mutual induction

Autotransformers use

self induction

Can I calculate current with a transformer?

Yes, but it’s a function of voltage, inversely proportional

Rheostat

kVp major and minor, mA selector, also always regulates voltage but ALSO can operate on AC or DC

A machine is using 200 mA, .40 sec, 40 in SID. The machine has 80 windings on the primary side of thestep up transformer and 100,000 windings on the secondary core. What is the secondary voltage of primary voltage is 72?

90,000 volts

What is the current on the secondary side in mA if the primary current is 20 amps?

16 mA

Timer

Is located on the primary side of the step up transformer because it controls the amount of time that the voltage (kv) drive electrons from the negative side to the positive

Why do we check the timer?

It breaks relatively frequently and is much less expensive to fix than the transformer

spining top test equation

# of imps/sec

Single phase timer checks

measures number of dots

3 phase timer checks

measures degree of arc