How to isolate the transformer of medical equipment

In medical equipment, electrical safety is one of the primary considerations. Because medical equipment is often in direct or indirect contact with human body, especially in high-risk environments such as operating room, monitor and dialysis machine, the equipment must have a high degree of electrical insulation and isolation ability to prevent the occurrence of dangerous situations such as electric shock and short circuit. As a key component of power supply system, transformer plays a vital role in realizing electrical isolation. This paper will discuss its working principle, structural design and safety standards around the theme of "how to isolate the transformer of medical equipment".

First, the basic concept of electrical isolation
　　lectrical isolation refers to the electrical separation between the two circuits by certain means, so that the current cannot flow directly, thus avoiding the harm caused by the current passing through the human body or other sensitive parts. In medical equipment, the main purpose of electrical isolation is to isolate the high-voltage side (such as mains electricity) from the low-voltage side (such as patient contact part) of the equipment, so as to ensure the safety of patients and operators.

Second, the isolation principle of medical equipment transformer

Medical transformers usually adopt the design of isolation transformers. Its core principle is to transfer energy between the input winding (primary) and the output winding (secondary) by electromagnetic induction, instead of directly connecting them by wires. This design realizes the electrical isolation between input and output.

One or more insulating materials, such as polyester film, epoxy resin and silica gel, are usually added between the primary and secondary windings of transformers to enhance the isolation effect. In addition, some high-end medical transformers will adopt shielding technology to reduce electromagnetic interference and further improve isolation performance.

Third, the special requirements of medical grade transformer

Compared with ordinary industrial transformers, transformers used in medical equipment need to meet stricter safety standards. For example:

-IEC 60601-1 standard: This is a general standard for the safety of medical electrical equipment widely used in the world, which clearly stipulates the key parameters of transformers such as isolation voltage, leakage current, creepage distance and electrical gap.

-Higher insulation level: Medical transformers are usually required to reach the insulation level of BF type or CF type application parts, which means higher isolation requirements for the direct contact parts of patients.

-Low leakage current control: In order to prevent discomfort or danger caused by weak current passing through human body, the leakage current of medical transformer must be limited to a very low level, usually not exceeding 10μA A..

Fourth, the structural design ensures isolation performance
　　In order to ensure good isolation effect, there are many considerations in the structural design of medical transformer:

1. Physical spacing design: ensure that the air gap and creepage distance between primary and secondary windings meet the standard requirements.

2. Material selection: Use materials with high voltage resistance and high insulation performance as isolation layers between windings.

3. Sealed packaging: Many medical transformers adopt potting process, and the whole transformer is encapsulated in insulating resin, which not only enhances the isolation performance, but also improves the moisture-proof and corrosion-resistant capabilities.

V. Summary

In modern medical equipment, the electrical isolation function of transformer is not only the basis of normal operation of equipment, but also the key link to protect the safety of patients and medical staff. Through scientific electromagnetic induction principle, strict material and structure design and following international safety standards, medical equipment transformers can effectively isolate high-voltage and low-voltage systems, thus ensuring the stability and safety of equipment. In the future, with the continuous progress of medical technology, higher requirements will be put forward for the isolation performance of transformers, which will promote their continuous innovation in new materials and new processes.