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Rad Tech 110

Rad Tech 110. Circuits. Conditions Necessary X-ray Production. High voltage In the kilovoltage range Electrons A supply of electrons A need to stop the electrons suddenly. Types of Transformers. Shell type. Core type. How do transformers work?. They can only work using AC current

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Rad Tech 110

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  1. Rad Tech 110 Circuits

  2. Conditions Necessary X-ray Production • High voltage • In the kilovoltage range • Electrons • A supply of electrons • A need to stop the electrons suddenly

  3. Types of Transformers Shell type Core type

  4. How do transformers work? • They can only work using AC current • On the principle of induction • Mutual • Self • The basic premise is that AC current ‘induces’ alternating magnetic fields.

  5. Transformers work? • These alternating magnetic fields are distributed throughout the core of the transformer. • The alternating magnetic fields ‘induce’ an electrical current in loops (coils) of wire.

  6. What gets transformed? • Both voltage and current • In a step-up transformer the voltage is increased • The primary side (incoming) has less coils than the secondary (outgoing) side. • Because there are more coils on the secondary side a higher voltage is produced • Increases voltage is reflected as a higher amplitude of the waveform.

  7. At the same time as voltage increases the current correspondingly decreases. • This occurs due to the conservation of energy. • If you increase one aspect, voltage, you have to decrease the other, current. • (Voltagep)(currentp)=(voltages)(currents)

  8. Step down transformer • Here the primary side has more coils than the secondary side. • The result is a decrease in voltage through the transformer.

  9. The X-ray Circuit

  10. Three sections of the x-ray circuit • Operating (control) console • High voltage generator • X-ray tube

  11. Operating (control) console • Line voltage compensator • Autotransformer • kVp selector • mA selector • Timer • Pre-reading kVp meter

  12. Line voltage compensator The purpose of the line voltage compensator is to maintain a constant voltage to the system. In the modern system this is done automatically.

  13. Autotransformer The autotransformer works on the principle of self-induction. It has a single core and is responsible for varying the voltage. Because of its ability to adjust voltage, the autotransformer can be either a step-up or step-down transformer.

  14. kVp selector • kVp is adjusted at the autotransformer • Taps are available so that different voltages can be achieved.

  15. Pre-reading kVp meter • The kVp meter is considered pre-reading because it is not actually measuring kVp but measuring voltage off the autotransformer. • Remember, the autotransformer is used to adjust voltage.

  16. Timer • Historically, there have been many types of timers. • Today, all timers are electronic timers of various types. • mAs • Phototiming (AEC) • Regular electronic

  17. mA selector • Allows for adjust of the filament voltage • Precision resistors • Choke coil

  18. High Voltage Generator • Step-up transformer • High voltage transformer • High tension transformer • Step-down transformer • Filament transformer • Rectifiers

  19. Step-up Transformer • This transformer is responsible for producing the high voltages necessary for x-ray production. • Turns ratio of 500:1 or 1000:1

  20. Filament Transformer • Intended to lower voltage and increase current • Allows for thermionic emission to occur at the filament • Ultimately, provides the electrons necessary for x-ray production. • Tube current measured in mA.

  21. Rectifiers • Current traffic cops • Intended to allow electrons to flow in only one direction • Provide the mechanism that converts AC to DC current. • 4 rectifiers are required to fully convert AC to DC.

  22. Types of Circuits • Single phase • Full wave • Half wave • Three phase • 6 pulse • 12 pulse • Medium and High Frequency • Capacitor discharge • Found predominantly in portables.

  23. Single Phase • Full • Half

  24. Three phase • 6 pulse • 12 pulse

  25. Three phase transformers • Three phase units use delta and ‘wye’ transformers • 6 pulse • 2 ‘wye’ and 1 delta • 12 pulse • 2 delta and 1 ‘wye’ • They also require 12 rectifiers

  26. Advantages of 3 phase • Higher beam quantity and quality • Higher mA stations are also possible

  27. Why higher quantity and quality for three phase? • Because the voltage ripple is less • Basically when the tube is energized it stays energized. full 3 phase 12 pulse

  28. Medium/High Frequency Generator

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