High Voltage Supply

High voltage SuppliesGenerators should provide a smooth constant high voltage to the X-ray tube.

Transformers

ondary

primary

ondary

primary

V

V

number

number

secsec

Step up transformers

Nprimary= 100 Nsecondary = 50000

V primary = 240V V secondary = 120 kV

N primary

N secondary

Single phase Full Rectification

High frequency power supplies

Modern High Voltage supplies use a high high frequency chopped DC voltage (500V) which is transformed to a high voltage (74kV) The 500V DC signal is chopped at between 20kHz and 30 kHz and transformed using a step up transformer to 74kV. The smoothed supply may have a ripple of below 3%

A Typical Frequency Generator : HSA RPKilovolts      kV selections: 80,1 00,120, and 140 kV

      Basic kVp Accuracy: + 3% +/- (3% + 2kV) Excludes first 10msec of exposure

      kVp during first 10 ms: Basic accuracy +/- 5 kV

 Milliamperes        mA selections: 40 to 400 mA, by 10 mA increments

Patient scanning subject to tube limitations and 48kW maximum

Chopped 550 Supply

Resonance Voltage Control