Safety Protection Design of High-Voltage Power Supply for Electron Beam Additive Manufacturing

The safety protection of the high-voltage power supply for electron beam additive manufacturing should cover electrical safety, mechanical safety and process safety. A multi-level protection system is constructed according to the characteristics of high voltage (10-40kV) and high power output to avoid electric shock, equipment damage and process accidents.
Electrical safety protection is the core: a double insulation structure is adopted. The main circuit insulation layer uses high-voltage resistant polyimide film (breakdown voltage ≥ 100kV/mm), and the auxiliary insulation layer uses silicone rubber to ensure an insulation resistance ≥ 1000MΩ; a grounding protection system is set up, with a grounding resistance ≤ 4Ω. When insulation damage occurs, the leakage current is quickly led out through the grounding circuit, and at the same time, overcurrent protection is triggered to cut off the main circuit power supply, with a response time ≤ 10ms; for overvoltage risks, a multi-level voltage clamping circuit is designed. When the output voltage exceeds 10% of the rated value, the first-level clamping circuit absorbs overvoltage energy through a varistor. If the overvoltage persists, the second-level clamping circuit triggers thyristor short-circuit protection to prevent damage to power supply devices.
Mechanical safety protection focuses on structural design: the power supply shell is made of impact-resistant cold-rolled steel plate with a thickness ≥ 2mm, and the surface is coated with an insulating coating to avoid electric shock caused by accidental contact; a door lock linkage device is set up. When the power supply cabinet door is opened, the high-voltage output is automatically cut off, and high voltage cannot be started when the cabinet door is open to prevent safety hazards during maintenance; for the vibration environment (such as vibration during the operation of additive equipment), shock-absorbing foot pads (damping coefficient ≥ 0.3) are used to reduce the impact of vibration on the internal components of the power supply and avoid short circuits caused by loose wiring due to vibration.
Process safety protection should be combined with the characteristics of the additive process: real-time monitoring of electron beam current stability. When the beam current fluctuation exceeds ±5% and lasts for 3s, the acceleration voltage is automatically reduced to a safe value (≤ 5kV), and an alarm signal is sent to prevent printing defects or equipment overload caused by abnormal beam current; a vacuum interlock protection is designed. If the pressure of the vacuum chamber of the additive equipment exceeds 1Pa (electron beam melting requires a high vacuum environment), the high-voltage power supply is immediately cut off to avoid arc generation due to air ionization and damage to the electron gun and power supply; in addition, an emergency stop button is set up with a response time ≤ 1s, which can quickly cut off all outputs in emergency situations to ensure the safety of personnel and equipment.
Through the above multi-level protection design, the high-voltage power supply can meet the GB 15579.1 safety standard, provide reliable guarantee for the stable and safe operation of electron beam additive equipment, and reduce safety risks in the production process.