X -ray Generator

1. X-ray generators
Mr Sujan Poudel
B.Sc.MIT (2015)
Department of Radio Diagnostic and
Imaging

2. Outline
• Definition
• Components
• Types

3. Definition
Generators means an electrical device which
transform mechanical energy into electrical
energy.
But x-ray generator supplies electric power to
x-ray tube.
 x-ray generator begin with the source of
electrical energy.
Radiology department will have 3 phase power
available in range of 220V.

4. Components
Transformer
Rectifiers & capacitors
Subsidiary circuit

5. Transformer
Types of transformer used in x-ray equipment
Auto transformer
Filament transformer(step down transformer)
High voltage transformer(step up transformer)

7. Generators types
• Types
Single phase x-ray generator: uses single phase
voltage source(220V) and produces two pulse DC
waveform.

8.  3 phase six pulse generator: commercial
electric power is usually delivered as three
phase.

9. Contd……
phases 120o apart
Single Phase Power Three Phase Power

10. Contd..
Incoming 3-phase supply can be connected two
ways :
Star connection(wye connection):generally
secondary winding of transformer. It has 3 phase
and four wire system
In which one wire is earthed(zero volt)
So we can get line voltage ie 440 and phase
voltage ie 220v
Delta connection: generally primary winding of
transformer is delta connected

11. Rectifier
Convert AC into DC
PN junction is used as rectifier where P and N
are semiconductors
When +ve end is connected to P side and -ve
end is connected to N it is called forward
biased.

13. Working of Segment AB
• In 1st +ve half cycle when point A is (–ve) and B is
(+ve).
• Diodes R3 & R2 gets forward biased and R1& R4
gets reverse biased
• Flow of electron is from point A R3 Filament-
anode R2 finally to (+ve) terminal B
• In next (–ve) half cycle when point A is (+ve) and B
is (–ve)
• Diodes R1 & R4 gets forward biased and R3 & R2
gets reverse biased.
• Flow of electron is form point B R1 filament
anode R4 finally to (+ve) end A.

14. 3 phase 12 pulse x ray generator
To obtain 12 pulse from six phase an additional
delta connection is added on secondary
winding of transformer.
So delta lags wye by 300 that means in each
300 phase difference a pulse is obtained. So,
total 12 pulse can be obtained.

15. 4

16. Working of segment AB
• IN 1st +ve half cycle of AC input
• Suppose end A becomes +ve and end B
become –VE
• Diodes R1& R6 gets forward biased and diode
R5 & R2 gets reversed biased
• Flow of electron from point B R1
xraytube R6 and to point A.
• After 300 output of delta is given out
• End A’ is +ve and B’ Is –ve
• Diodes R1’ and R6’ gets forward biased and
diode R5’ and R2’ gets reverse biased.

17. Contd..
• Flow of electron point B’ R1’ x-ray tube R6’
to +ve end A’.
• In –ve half cycle of AC input end A becomes –ve and
B becomes +ve.
• Diodes R5 and R2 gets forward biased and diodes R6
and R1 gets reverse baised.
• Flow of electron from point A R5 x-ray tube
• R2 and finally to positive end B.
• After 3o degree delta circuit is activated.

18. Contd…
High frequency x-ray generator:
uses high frequency
current to provide constant voltage to the x ray
tube.
Principle:
when high frequency current is fed to
primary winding of transformer it cause change in
magnetic flux which produces high voltage EMF in
secondary winding of transformer.
Output voltage obtained i.e V is directly
proportional to frequency to ac
No of turns of transformer
Area of iron core

19. Block diagram of high tension
transformer

20. Advantages
Independent of input power supply i.e it can
operate either in single phase input or 3 phase
input
Has less ripple factor ie (1%)
Compact in size so can accommodate in x ray
tube housing

22. Power discharge generators
Types
Capacitor discharge generator:
It uses high voltage capacitor
to store the charge and when exposure is done
discharging of capacitor occurs.
Battery powered generator:
It uses Ni-CD batteries to
supply input power to x ray tube.

23. Working
• DC supplied by nickel caddmium batteries
inverter high frequency AC
Transformer high voltage AC
Rectifiers high voltage pulsed DC
Capacitor high voltage smooth DC
X RAY TUBE
USES
• Used in mobile x ray unit for ward radiography.