Large medical equipment electric deepen design brief

Summary: this article to the PLA General Hospital project, for instance, introduced on a large medical equipment electric deepen design some experience, pointed out that design lies and Eagle professional engineer of communication and Exchange, on a correct understanding of English information, really grasp the device installation process and works.

China people's Liberation Amy Hospital Oncology Center building after 2 years was finally completed in use, it is Asia's most advanced cancer treatment centre, second floor, ground floor 15-story building area 3.5 million m2 of single body, with 26 sets of large medical equipment (cyclotron, faults Accelerator, DSA, PET/CT, DR, high-frequency heat therapy machine, Simulator, brachytherapy, etc.), of which 10 units are the first to introduce, as the engineering design of main electric specialty, each device are accompanied with many international equipment manufacturers, communication, design, validation, and then design, plot construction, tie, debugging steps process although difficult, but the harvest, see one received a smooth use of equipment, reception services in the community of the scene, that feeling unutterable.

Just want to put myself in with some deepening design technology to harvest some summary for peer reference.

Large medical equipment electrical design requirements will vary depending on the manufacturer of the differences, the key lies in the design and equipment manufacturers of professional engineers of communication, understanding of English information, real understanding device installation process and works.

Following the design of technology focused and difficult to do as follows.

First, the field distribution box

The device host must be equipped with dedicated on-site distribution box, the distribution box, as well as connected with on-off switch (EAT) and emergency switch (AT) must be installed before the installation in place.

Auxiliary equipment and other electrical facilities (such as lighting, air conditioning, etc.) of the power supply shall be provided in the public power network of hospitals, their control and protection circuits can be installed on site distribution box, but definitely not allowed on-site distribution box to its power supply.

The following is inserted DSA device distribution box host power supply circuit circuit principle:

The system complies with national norms, voltage 380V, maximum deviation shall not exceed 10%.

Frequency is 50 Hz, the maximum deviations not exceeding 0.5Hz. Voltage between phases between maximum deviation shall not exceed the minimum voltage of 2%. Maximum power for equipment, continuous power 20KVA 171KVA, power factor 0.9; equipment maximum peak current is a continuous current of 289A, 31A, you can use the rated current for circuit breakers 160A of empty open for protection. Equipment requirements for green electricity. Three-phase line indicating the phase sequence and a PE line and introduces distribution Cabinet. Wire cable must use multiple strand cable access inside the rated current for circuit-breakers 160A, and cable colors and breaker specification must conform to the standard Handbook for electrical installation. Distribution Cabinet must possess anti-open lid lock function to ensure electrical safety jobs. Distribution cabinet installation of emergency power-off button in the operations console in between the wall next to the operator in the event of an emergency power down the system.

Second, the system power supply cable

From the transformer to the field distribution box it is best to configure a dedicated power cable, and must be for copper conductor cable.

On the power cable are not allowed to access power inductive load such as air conditioning, elevators, freezer, etc. to avoid when starting and stopping the device causing the interference. In order to guarantee the power supply line resistance meets the requirements of the table, must be based on the actual length of the cable laying, transformer output with internal resistance as well as on-site distribution box of their own internal resistance, calculated by laying cable minimum cross-sectional area, laying length longer, transformer output and onsite distribution box of internal resistance, the higher the required cable section. Cable cross section area of selection can be calculated with the following experience:

Cable section A = (2 × laying length)/(56 × resistance of the cable itself).

Example: actual measured to: cable laying length 100m, transformer output with internal resistance 0.060 Chin ohm, onsite distribution box's own internal ohmic resistance 0.030 Chin.

Then: cable's own maximum allowed resistance = 0.11-0.06-0.03 = 0.02.

Cable section A = (2 * 100)/(56 × 0.02) = 178.5, cable section should at least 185mm2.

Third, the lighting requirements

Preferably by constant fluorescent lighting and adjustable incandescent lighting in the form of systems to meet the patient's comfort and convenience of the staff of the operation.

The following is inserted as an example, DSA recommends the following lighting scenarios:

IV. use of common grounding system and equipotential connection

Early in the design, device manufacturers will require separate earthing, we should be understood as the equipment to grounding plate grounded on the reattachment of other equipment in order to avoid interference.

Rather than individual play ground electrode. When we encountered some manufacturers stubborn requires a separate play ground, not adopt our common ground, I should start with the following aspects of interpretation.

1. international standard IEC61312 — 1. United States electrical code (NEC). Our lightning protection specification (section 6.3.3 and 6.3.4) require use of common grounding system and equipotential connection.

2. in the use of common grounding system of the electronic equipment in the building, to set up separate earthing is difficult.

Because the device shell, the entire building of metal structures, steel, electric protection earthing system access common grounding system. If you want to separate from an electronic device (function) the Earth wire leads to the outdoor separate ground electrode, and want to share with the grounding system totally isolated to prevent strikes back over voltage is difficult.

3. a separate dedicated grounding in high-frequency (information device frequency), the impedance is high, therefore requires resistance small is meaningless.

Because the self resonance dedicated grounding impedance infiniteLarge, equivalent to disconnect, become a antennas, enables the device to accept interference signals.

4. separate earthing protection against overvoltages.

5. in TN-S system context does not have to worry about power frequency current noise electronic equipment (PE and n is the number of separate, PE usually without current).

More in electronic devices, should be filled and closed steel wire packing lines, to avoid single-phase short-circuit current flows through the more common grounding system, causing interference to electronic equipment.

So in engineering design, on a number of foreign and domestic manufacturers follow old standards require separate grounded approach to redress.

These are large electrical medical equipment room, deepening the exchange of experience in the design, if it has not enough, please put forward correct me!

Reference documents

1. <<民用建筑电气设计规范>> JGJ/T16-92

2. United States GE Medical Equipment Division provides equipment information

3.IEC60364-7-710 INTERNATIONAL STANDARD