High Voltage X-Ray Generator failure and repair

The focus of this blog however is the X-Ray generator system, more specifically the High-Voltage Generator.

Function of High Voltage Generator and its Key components

In order for the electrons to accelerate from cathode and strike the anode at high speed to produce X-Rays, a high potential needs to be sustained in the x-ray tube between the anode and the cathode. The line voltage is converted to high voltage required to maintain high potential between cathode and anode (typically between 20 kV and 150 kV for medical applications) using a high voltage transformer or step-up transformer. Another component in the high voltage generator includes the filament or step-down transformer, which provide power to cathode filament. 

In HF X-Ray machines, the X-ray generator involves a high-frequency generator using a high-frequency inverter typically made up of a high-frequency oscillator, a high-frequency high-voltage transformer, a high-frequency high-voltage rectifier, and a high-frequency high-voltage filter.  All X-ray generators use a high-voltage divider to measure the high-voltage outputs accurately. High-voltage capacitors and resistors and various other electronic components used in HV generators are costly.

The high-voltage output of the X-ray generator is connected to the X-ray tube anode and cathode with a pair of high-voltage coaxial cables.

Causes of HV Generator Failure

The X-Ray tubes are filled with dielectric oil for the purpose of insulation and cooling. Over time with usage, the dielectric strength of the insulating oil in the tube diminishes. This is one of the reasons for tube arcing. Tube arcing, which is a common problem in x-ray tubes, may cause a short circuit across the tube end of the high-voltage cable. This short circuit could reflect back most of the energy received from the line. Both the oncoming and reflected energy coming together could cause a very large voltage spike at the generator end of the line. The voltage spike thus caused, results in energy oscillattion along the line in the HV Cable for some time, till it is fully dampened. Due to this large voltage spike, output components, such as capacitors and resistors and HV cable of an X-ray generator could be damaged, if unprotected, when the X-ray tube arcs.

The other points of failure are the cable sockets at the junction of the HV Cables to the HV generator or the X-Ray tube end. The HV Cables are connected to the two ends with sockets that may crack with stress of usage over a period of time, resulting in leaks and disconnections.

Sometimes the HV transformer or filament transformer can fail due to windings damage. The copper wire windings, that form the main part of a transformer, withstand dielectric, thermal and mechanical stress during in the x-ray generation process. The winding may break, burn-out or get punctured etc. Transformer windings need to be restored.

HV Generator Repair

In some cases the HV generator fails due to damage to HV Cables. In such cases the HV Cables may need replacement. In case of components failure, the HV x-ray generator could be repaired by replacing faulty components.

Should you ever face arcing issues, HV generator failure or other problems in the X-Ray tube, contact us! PrimedeQ can assist you with HV generator repair, cable sockets replacement, HV Cable repair/ replacement, transformer windings, x-ray tube oil re-filling, vacuum treatment services and several other types of X-Ray repair services.