Transformers in the x-ray unit

Question 1

The auto transformer

Answer 1

• It taps its voltage from the mains supply
• The power supplied to the x-ray imaging system is first delivered to the autotransformer
• It consists of a laminated soft iron core with only a single winding on it (self-induction)

Question 2

Functions of the autotransformer

Answer 2

• Compensation of the mains line voltage
• Provide voltage for the filament circuit
• Provides a primary voltage for the HTT
• Provision of the method for varying the voltage

Question 3

Advantages of the autotransformer.

Answer 3

• It is relatively simple, robust and fairly small
• Able to accommodate a large number of tapping’s on the input and output side.
• Operated using controls sited on the x-ray units control panel
• Able to control the output of the high tension transformer(HTT) by varying the voltage supply to the primary winding of the HTT.

Question 4

Function of the filament circuit

Answer 4

To heat the filament to very exact temperatures so that the # of electrons freed by the thermionic emission is just right for x-ray generation

Question 5

Main components of the filament circuit

Answer 5

1. Voltage/filament stabilizer,
2. Space charge compensator,
3. mA selector
4. Filament transformer.

Question 6

Filament stabilizer

Answer 6

• The voltage stabilizer ensures that the voltage supplied to the filament remains constant, despite fluctuations in the main power supply.
• connected to the filament circuit immediately after the ATF

Question 7

2 main functions of the filament circuit

Answer 7

• Ensures that the voltage supplied to the filament remains constant, despite fluctuations in the main power supply.
• To compensate for any change in the mains frequency to overcome the effect of frequency change on the filament.

Question 8

Space charge compensator and Kvp

Answer 8

• At lower kVp settings, the space charge effect is more pronounced, which can reduce the efficiency of electron flow.
• The space charge compensator mitigates this effect, allowing for stable electron emission even at lower kVp

Question 9

space charge compensator

Answer 9

• The space charge compensator helps to stabilize the electron emission from the X-ray tube’s filament.
• It compensates for the space charge effect, which is the repulsion between electrons in the electron cloud around the filament.
• This effect can limit the number of electrons that reach the anode, especially at lower kVp settings1

Question 10

mA selector

Answer 10

• The mA selector adjusts the amount of current flowing through the X-ray tube’s filament. This current determines the number of electrons emitted by the filament, which in turn affects the number of X-ray photons produced