International Electrotechnical Commission IEC60364 standards set forth in the medical field, from the mains supply, or surgery for life-sustaining medical electrical equipment and lighting for theater lighting and similar equipment, the rated voltage exceeding AC25V or DC60V equipment, insulation resistance must be used with monitor IT systems. Objective Medical Isolated Power Systems (IT systems) is to ensure the provision of places for medical appliances within a safe and reliable power to ensure patient safety.

Chinese name: Medical Isolated Power Systems (IT systems)

Definitions: ungrounded power distribution system

Unit: International Electrotechnical Commission

Standard: IEC60364 standard

"Medical Isolated Power System" Introduction

First, the need for the medical field selected IT systems:

(IT systems, ie ungrounded power distribution system)

1. IT systems due to reduced contact voltage and power grids on Earth leakage current (direct and effective control of the leakage current of the heart), so the risk of electric shock after the personal level is minimized;

As we all know, when the electrical equipment of the human heart directly drain more than 10uA, it can cause electrical shock to the patient's micro injured accident. In general use buildings used RCD, ELCB and other earth leakage protection switch, which action response is mA level (eg: 30 mA), can not meet the needs of the medical field.

So, now the international medical field operating room, ICU, CCU and other important places usually localized "ungrounded power system" (ie "IT System" or "isolated power system.") Power supply. Single phase 3KVA-10KVA of Medical Isolated Power supply to these places, first to prevent other power supply circuit leakage current security threat fleeing the operating room, ICU, CCU medical electrical equipment to the patient through the ground line; In addition, Once isolated the power of the connected load (such as a variety of medical electrical equipment) ground fault occurs, because of the ground can not constitute a loop, can only produce a small capacitive leakage current, which greatly protect the patient from leakage current injury.

2. When the network load-side first insulation fault occurs, it will not cause the power breaker operation (tripping),

To ensure the continuity of supply;

In the medical field, some places demanding continuous power supply, so the design into two (or even triple) power supply (ground power supply system) automatically switches to ensure continuity of supply of these special places. But if the load side relative insulation fault occurs, the fault current through the neutral point of the power to form a loop, to form a large fault current, the fuse on an empty open or actions, resulting in power outages. And if the local power distribution system using IT in these special places, because of the power ungrounded, when the load side relative to the first point appears insulation fault, because it does not constitute a ground loop, only produce a small capacitive leakage current on the human body without harm, but the action will not lead to open space, thus ensuring the operating room supply connectivity.

3. reduces the leakage current, it improves fire safety.

Second, the domestic / foreign regulations:

Many national and international standards for the medical field, especially in life and death of those places, such as operating room, intensive care unit, cardiac care unit and other appliances made special provisions. Its purpose is to ensure the provision of places for medical appliances within a safe and reliable power to ensure patient safety. Related criteria are as follows:

German DIN VDE 0107

Austria OEVE-EN7

French NFC 15-211

Italian CEI 64-4

US NFPA 99-1993

Australia AS2500

British HTM2007 / 2014, BS7671

Brazil NBR 13543

IEC (International Electrotechnical Commission) 6034-7-710

International Electrotechnical Commission IEC60364 standards set forth in the medical field, from the mains supply, or surgery for life-sustaining medical electrical equipment and lighting for theater lighting and similar equipment, the rated voltage exceeding AC25V or DC60V equipment, insulation resistance must be used with Monitor IT systems.

Meanwhile, China's "civil electrical design specifications" in 14.7.6.3 states that "after a power interruption, has incurred significant medical dangerous place, should be ungrounded power system (IT system) power supply"; 14.2.8 the provisions "IT systems to be fitted with insulation monitoring and earth fault alarm system or a display device." As well as our November 26, 2002 release, December 1 start of the "cleansing operation of the hospital building technical specifications" 8.3.1.3 provides that "cleansing operation of the electricity of the buildings should be designed with the supply and distribution center. Depending on site requirements, the main choice of TN-S system, and two forms of IT systems "; 8.3.2.3 provides that" power should clean the operating room equipment leakage detection alarm system "; 8.3.4.2 provides that" cardiac surgery operating room must be provided with Medical Isolated Power functional grounding system "and other relevant regulations.

Third, the new (changed) to build hospitals choose how to design IT systems:

1. In the medical field to check all or therapeutic purposes, the device in direct contact with the patient (including wires), there are three types of applications:

● Apply Group Class 0: do not use mains power medical electrical equipment within the health facilities.

For example: patient room, waiting room, massage room, etc.

● Apply Group Class 1: within the medical options are available using the mains supply medical electrical equipment, which no member is inserted into the patient's body.

For example: ward, maternity ward, X-ray room

● Apply Group categories: the medical options are available to use grid power medical electrical equipment, these devices for cardiac surgery or inside the body, real-time monitoring of the patient or for maintaining the patient's life and so on.

For example: anesthesia room, operating room, surgery preparation room, surgical plaster room, surgical recovery room, cardiac catheterization room, intensive care unit, cardiac care unit, angiography room, premature child care room.
In the application group 2 class medical facilities must use isolated power system with insulation resistance monitoring (IT systems). Application Group Class 0 and Class 1 medical facilities can be used with a ground leakage current protection system, namely TN-S system.

2. Recommends grid electricity access to IT equipment:

a) the ventilator b) incubator

c) dialysis equipment d) anesthesia equipment

e) patient monitoring equipment f) high-frequency surgical equipment

g) infusion pump h) injection pump

i) heart-lung machine j) effort recorder

k) Pulse machine l) electronic pulse rhythm regulators, etc.

3. The operating room / ICU ward / CCU ward IT power system basic configuration:

⑴ Medical Isolated Power

⑵ Insulation Monitor

⑶ transformer load and temperature monitoring device

⑷ external alarm display device