This standard applies to information technology equipment powered by mains power or battery with a rated voltage not exceeding 600V, including electrical business equipment and related equipment. This standard also applies to information technology equipment designed and intended to be directly connected to a communication network, regardless of the power supply method. This standard also applies to information technology equipment designed to use AC mains power as a communication transmission medium (see Note 4 to Chapter 6). This standard specifies a series of requirements to reduce the risk of fire, electric shock or injury to operators and laymen who may come into contact with the equipment. When specifically stated, maintenance personnel are also included. This standard is intended to reduce the risks of installed equipment when it is installed, operated and maintained in the manner specified by the manufacturer. The installed equipment can be a system consisting of several devices interconnected, or a system consisting of several independent devices. The following equipment is included in the scope of this standard: accounting machines, bookkeeping machines, calculators, cash registers, copiers, data circuit terminal equipment, data preprocessing equipment, data processing equipment, data terminal equipment, dictation equipment, shredders, copy machines, electric plotters, degaussers, fax machines, key telephone systems, tape reels, mail processing machines, micro-office equipment, modems, currency processing machines [including automatic teller (cash dispensing) machines], electric document conveyors, automatic user exchanges, file sorting machines, document finishing machines (including punchers, cutters, sorters), pencil sharpeners, personal computers, photo printing equipment, plotters, sales terminals (including related electronic scales), postage machines, public information terminals, staplers, telephone answering machines, telephones (wired and wireless), text processing equipment, typewriters, visual display devices, printers, scanners, routers. Multimedia equipment, network terminal equipment, radio base stations, repeaters, communication switching equipment, etc. The equipment listed here is not all-inclusive, so equipment not listed is not necessarily out of the scope of this standard. Equipment that complies with the relevant requirements of this standard can be considered to be able to be used in conjunction with process control equipment, automatic test equipment and similar systems that require information processing. However, this standard does not include requirements for the performance or functional characteristics of the equipment. For the following equipment, it may be necessary to add some requirements to the safety requirements specified in this standard - Equipment intended to operate under special environmental conditions such as extremely high or low temperatures, excessive dust, high humidity or severe vibration, flammable gases, corrosion or explosion; - Medical electronic equipment directly connected to the patient's body; - Equipment to be used in vehicles, ships or aircraft, equipment used in tropical areas or on plateaus above 2000m; - Equipment intended for use in places where water may enter. The requirements for these equipment and related test guidelines are shown in Appendix T. GB 4943-2001 Safety of Information Technology Equipment GB4943-2001 Standard Download Decompression Password: www.bzxz.net

GB 4943-2001
All technical contents of this standard are mandatory. Foreword
This standard is equivalent to the third edition of the international standard IEC60950:1999 Safety of Information Technology Equipment. This standard is the second revision of GB4943. GB4943-1990 is equivalent to the first edition of IEC950-1986, GB4943-1995 is equivalent to the second edition of IEC950-1991, and this standard is equivalent to the third edition of IEC60950. The second edition adds Chapter 6 "Connection to Communication Network". The main changes of the third edition compared with the second edition are as follows: the safety requirements for connection to the communication network have been incorporated into the subject of the standard, and the content of the standard has been reorganized, and related topics have been merged together, which is more convenient to use; at the same time, technical updates have been made to the problems raised by various certification organizations during use. The purpose of this standard is to play a guiding role in the safety of the design, production and use of information technology products in my country; at the same time, product safety certification should be implemented in accordance with this standard to ensure that the products meet the safety requirements. This standard shall replace GB4943-1995 from the date of implementation. The appendixes A, B, C, D, E, F, G, H, J, K, L, M, N, P, U and V of this standard are normative appendices, while the appendices Q, R, S, T, W and X of this standard are informative appendices. This standard is proposed by the Ministry of Information Industry of the People's Republic of China. This standard is under the jurisdiction of the China Electronics Standardization Institute. The drafting unit of this standard is the China Electronics Standardization Institute. The main drafters of this standard are Li Lanfen, Wang Ying and Jia Zhen. The first release date of this standard is December 28, 1990. The first revision date of this standard is December 21, 1995. GB 4943-2001
IEC Foreword
1) IEC (International Electrotechnical Commission) is a global standardization organization composed of national electrotechnical committees (IFC National Committees). The purpose of the IEC is to promote international cooperation on standardization issues in the electrical and electronic fields. To this end, the IEC publishes, among other activities, international standards. The preparation of international standards is undertaken by technical committees, and any IEC national committee concerned with the subject matter may participate in the preparation of standards. Any international, governmental and non-governmental organization in contact with the IEC also participates in the preparation of international standards. The IEC maintains a close cooperative relationship with the International Organization for Standardization (ISO) under conditions agreed upon between the two organizations. 2) The formal resolutions or agreements of the IEC on technical issues are made by technical committees participated in by national committees with special concerns about these issues, and represent the international consensus on the issues involved as far as possible. 3 These resolutions or agreements are published in the form of standards, technical reports or guidelines, and are recommended for international use and, in this sense, are recognized by the national committees.
4 In order to promote international unification, the national committees of the IEC have the responsibility to adopt IEC standards as far as possible in their national and regional standards. Any differences between the IEC standards and the corresponding national or regional standards should be indicated in the national or regional standards. 5) The IEC does not express recognition in the form of a mark, nor does it assume responsibility for any equipment that claims to comply with its standards. 6) Attention should be drawn to the fact that some clauses of this International Standard may be subject to patents. IEC is not responsible for confirming these patent rights. International Standard IEC 60950 was proposed by IEC Committee 74 (Safety and Energy Effects of IT Equipment). The third edition cancels and replaces the second edition published in 1991 and its amendments 1 (1992), 2 (1993), 3 (1993) and 4 (1996), constituting a technical revision. The text of this standard is based on the following documents:
74/498/FDIS
Report on the voting
74/504/RVD
Details of the voting results of this standard can be found in the voting reports listed in the table above. Annex A, Annex B, Annex C, Annex D, Annex E, Annex F, Annex G, Annex H Annex J, Annex K, Annex 1, Annex M, Annex N, Annex P, Annex U and Annex V form an integral part of this standard. Appendix Q, Appendix R, Appendix S, Appendix T, Appendix W and Appendix X are for information purposes only. In this standard, the following fonts are used: - Requirements and difficult appendices: Traditional Chinese Www.bzxZ.net
- Inspection and test regulations: Traditional Chinese
- Notes and other prompts: Small traditional Chinese - Standard conditions in the table; Small traditional Chinese
- Terms specified in 1.2; Small letters
GB 4943—2001
0 Principles of safety
The following principles were adopted in the formulation of this standard. Introduction
These principles do not involve the performance and functional characteristics of the equipment. 0.1 General principles of safety
In order to design safe equipment, the designer must understand the basic principles of safety requirements. These principles cannot replace the detailed requirements of this standard, but only let the designer understand the principles on which these requirements are based. If the technology, materials or structural methods involved in the equipment are not clearly specified, the design of the equipment should at least achieve the safety level described in this safety principle. Designers should not only consider the normal working conditions of the equipment, but also the possible fault conditions and the resulting faults, foreseeable misuse and external influences such as temperature, altitude, pollution, humidity, overvoltage of power grid and overvoltage of communication lines. When determining which design scheme to adopt, the following priorities should be followed: 1. If possible, specify the design principles that can eliminate, reduce or protect against dangers; 2. If the implementation of the above principles will weaken the function of the equipment, then protection measures independent of the equipment should be used, such as personal protection equipment (not specified in this standard). 3. If the above schemes and other measures are not feasible, then measures to mark and explain the remaining dangers should be taken. The safety of two types of personnel needs to be considered, one is the user (or operator) and the other is the maintenance personnel. Users refer to all personnel except maintenance personnel. Safety protection requirements are based on the assumption that users have not been trained on how to identify dangers, but will not deliberately create dangerous conditions. Therefore, in addition to providing protection for designated users, these requirements also provide protection for sanitation personnel and temporary visitors. Generally, users should be restricted from accessing hazardous parts. To this end, such parts should only be located in the maintenance personnel access area or in the equipment in the restricted access area. If users are allowed to enter the restricted access area, they should be properly indicated. Maintenance personnel are professionals who can use their training and skills to avoid possible harm to themselves or others when there is an obvious danger in the maintenance access area of ​​the equipment or the equipment in the restricted access area. However, maintenance personnel should be protected from unexpected dangers. This can be done by, for example, placing the parts that are to be touched during maintenance away from electrical and mechanical hazards, setting up shielding to avoid accidental contact with dangerous parts, and using signs or warning instructions to remind maintenance personnel of residual dangers. Information on potential hazards can be marked on the equipment or provided with the equipment according to the possibility and severity of the harm it causes, so that maintenance personnel can obtain it. Generally, users should not be exposed to possible danger of injury, so the information provided to users is mainly to avoid misuse and potentially dangerous conditions, such as incorrect power connection and replacement of fuses with incorrect models. For mobile equipment, the power cord may be subjected to additional stress, which may cause the protective grounding wire to break, which will increase the risk of electric shock. For handheld equipment, the power cord is more likely to be worn, which is more dangerous. If the equipment falls, it may cause more serious danger. Portable equipment increases the number of dangerous cases because it may be used and carried in any direction. If a small metal object enters the opening on the casing, it may move inside the equipment and may cause danger. 0.2 Danger
The purpose of applying safety standards is to reduce the possibility of injury or harm caused by the following hazards: - Electric shock;
GB4943-2001
--Energy-related hazards Electricity
-Fire
Heat-related hazards!
- Mechanical hazard
- Radiation,
- Chemical hazard.
0.2.1 Electric shock
Electric shock is caused by the passage of electric current through the human body. The physiological reaction caused by the electric shock depends on the magnitude and duration of the current value and the path it takes through the human body. The current value depends on the applied voltage and the impedance of the power source and the impedance of the human body. The impedance of the human body depends in turn on the humidity of the contact area and the applied voltage and frequency. A current of about 0.5mA can produce a reaction in a healthy human body.Moreover, this unconscious reaction may lead to indirect harm. If the current is larger, it will have direct effects, such as burns or ventricular fibrillation. Under dry conditions, the peak voltage of up to 42.4V or the DC voltage of up to 60V on the contact area equivalent to one human hand is generally not considered to be a dangerous voltage. However, exposed parts that must be touched or operated by hand during use should be placed at ground potential or be appropriately isolated. Some equipment is intended to be connected to telephones and other external networks, and some communication networks are working. Signals (such as sound or ringing) are added to the steady DC voltage, and the sum will exceed the above-mentioned steady-state voltage value; and telephone company maintenance personnel often directly operate the parts of such circuits with their hands, but no serious injuries have occurred. This is because they use a well-designed handheld conductor, and the contact area of ​​the exposed conductor operated by the maintenance personnel is usually limited. However, the area where the user can touch the parts and the accessibility of the parts should be further limited (for example, by the shape and location of the parts). In order to prevent the user from being shocked, two levels of protection are usually required. Therefore, the equipment shall not cause electric shock hazard when operated under normal working conditions and under single fault conditions (including other faults caused by it). However, additional protective measures (such as protective earthing or additional insulation) cannot be used to replace well-designed basic insulation or reduce the requirements for basic insulation. Possible causes of danger
Contact with exposed parts that normally carry dangerous voltage. Breakdown of insulation between parts that carry dangerous voltage and accessible conductive parts under normal conditions.
Contact with circuits connected to communication networks with peak voltages exceeding 42.4V or DC voltage exceeding 60V.
Breakdown of insulation accessible to users.
Examples of methods to reduce the risk of electric shock from parts with dangerous voltage to accessible parts
Prevent users from contacting parts with dangerous voltage by fixed or locked devices, safety interlocks, etc.: Discharge accessible capacitors with dangerous voltage.
If basic insulation is used and accessible conductive parts and circuits are grounded, the accessibility to hazardous voltages is limited by the overcurrent protection device disconnecting the low-impedance fault-prone parts within the specified time: either a metal shield connected to the protective earth is installed between the cold parts, or double insulation or reinforced insulation is used between the parts so that the insulation between the accessible parts will not be broken down. Limit the accessibility and contact area of ​​such circuits and isolate them from ungrounded and unrestricted contact parts. The insulation accessible to users should have sufficient mechanical and electrical strength to reduce the possibility of contact with hazardous voltages. Limit the contact current to the specified value, or provide a more reliable contact current (leakage current), or the protective earth connection fails. Connect the protective earth connection. The touch current may include the current generated by the electromagnetic compatibility (EMC) filter element connected between the primary circuit and the accessible parts. GB 4943—2001
0. 2. 2 Energy-related hazards
When adjacent electrodes of a high-current power supply or a high-capacitance circuit are short-circuited, the following hazards may occur: combustion
-arcing
spilling of molten metal.
In this regard, even contact with circuits with safe voltages may be dangerous. Methods for reducing this hazard include:
Isolation:
Acid-free;
Use of safety interlocks.
0.2.3 Fire
Overload, component failure, insulation breakdown or loose connections under normal operating conditions may produce dangerously high temperatures. However, it should be ensured that the flames generated by the ignition point in the equipment will not spread beyond the immediate area of ​​the fire source and will not cause damage to the surrounding area of ​​the equipment. Methods to reduce this hazard include:
Provide overcurrent protection devices;
Use structural materials with appropriate combustion characteristics that meet the requirements; select parts, components and consumables to avoid high temperatures that may cause fire; limit the amount of flammable materials used;
Shield or isolate flammable materials from possible ignition sources; use protective fillings or baffles to limit the spread of fire to the inside of the equipment; use suitable materials to make the casing to reduce the possibility of fire spreading to the outside of the equipment; 0.2.4 Heat-related hazards
High temperatures under normal operating conditions may cause the following hazards: burns caused by contact with hot accessible parts; degradation of insulation levels or performance of safety components; ignition of flammable liquids.
Methods to reduce this hazard include:
Take measures to avoid high temperatures in accessible parts; - Avoid temperatures above the ignition point of the liquid: If contact with hot parts is unavoidable, provide warning signs to inform users. 0.2.5 Mechanical hazards
The causes of danger are:
Sharp edges and corners:
Moving parts that may potentially cause harm; Instability of equipment;
Fragments from imploding cathode ray tubes and bursting high-pressure lamps. GB 4943—2001
Methods to reduce this hazard include:
Rounding sharp edges and corners 1
Equip with protective devices:
-Use safety interlocks;
Make floor-standing equipment sufficiently stable: - Choose cathode ray tubes that can resist implosion and high-pressure lamps that can resist bursting: - Provide warning signs to inform users when contact is unavoidable. 0.2.6 Radiation generated by vehicle radiation equipment may pose a hazard to users and maintenance personnel. Radiation may be audio frequency radiation, radio frequency radiation, infrared radiation, ultraviolet radiation and ionizing radiation, high-intensity visible light and phase light (laser) radiation. Methods to reduce this hazard include:
--limit the energy level of potential radiation sources;
screen radiation exposure;
use safety interlock devices;
-if exposure to vehicle radiation hazards is unavoidable, provide warning signs to inform users. 0.2.7 Chemical hazards
Contact with certain chemicals or inhalation of their gases and fumes may be dangerous. Methods to reduce this hazard include:
avoid the use of accumulated and consumable materials that may cause harm due to contact or inhalation when the equipment is used under the intended and normal conditions;
avoid tea parts that may leak or vaporize; provide warning signs to inform users of the danger. 0.3 Materials and components
The materials and components used in the equipment structure should be appropriately selected and reasonably configured so that the equipment can operate safely and reliably during its intended life without causing any danger and, in the event of a serious fire hazard, without exacerbating the spread of fire. The selected components should remain within the rated values ​​set by the manufacturer under normal operating conditions and should not cause any danger under fault conditions. 1 General
1.1 Scope
National Standard of the People's Republic of China
Safety of information technology equipment
Safety of information technology equipment 1.1.1 Equipment to which this standard applies
GB 4943-2001
eqIEC60950:1999
Generation GB4943—1995
This standard applies to information technology equipment powered by mains or batteries with a rated voltage not exceeding 600V, including electrical business equipment and related equipment.
This standard also applies to information technology equipment designed and intended to be directly connected to a communication network, regardless of the power supply method. This standard also applies to information technology equipment designed to use AC mains power as a communication transmission medium (see Note 4 to Chapter 6). This standard specifies a series of requirements to reduce the risk of fire, electric shock or injury to operators and laymen who may come into contact with the equipment. When specifically stated, maintenance personnel are also included. This standard aims to reduce the risk of installed equipment when it is installed, operated and maintained in the manner specified by the manufacturer. The installed equipment can be a system composed of several equipment units interconnected, or a system composed of several independent equipment. The equipment that falls within the scope of this standard are listed below: accounting machines, bookkeeping machines, calculators, cash registers, copiers, data circuit terminal equipment, data preprocessing equipment, data processing equipment, data terminal equipment, dictation equipment, shredders, copiers, electric plotters, degaussers, fax machines, key telephone systems, tape winders, mail processing machines, micro-office equipment, modems, market processing machines [including automatic teller (cash dispensing) machines], electric document conveyors, automatic user exchanges, file sorting machines, file finishing machines (including punchers, cutters, sorters), pencil sharpeners, personal computers, photo printing equipment, plotters, sales terminals (including related electronic scales), postage machines, public information terminals, staplers, answering machines, telephones (wired and wireless), text processing equipment, typewriters, visual display devices, printers, scanners, routers, multimedia equipment, network terminal equipment, radio base stations, repeaters, communication switching equipment, etc. The equipment listed here does not include all equipment, so equipment not listed is not necessarily outside the scope of this standard. Equipment that complies with the relevant requirements of this standard can be considered to be able to be used in conjunction with process control equipment, automatic test equipment and similar systems that require information processing. However, this standard does not include requirements for the performance or functional characteristics of equipment. 1.1.2 Additional requirements
For the following equipment, it may be necessary to add some requirements to the safety requirements specified in this standard Equipment that is intended to work under special environmental conditions such as extremely high or low temperatures, excessive dust, high or severe vibration, flammable gases, corrosion or explosion!
Medical electronic equipment directly connected to the patient's body: Equipment to be used in vehicles, ships or aircraft, equipment to be used in tropical areas or on plateaus above 2000m above sea level; Equipment intended to be used in places where water may enter. The requirements for these equipment and the guidance for related tests are shown in Appendix T. Note: It should be noted that only certain national competent authorities require additional requirements. 1.1.3 Inapplicable Equipment
This standard is not applicable to:
-Security equipment, such as air conditioning, fire detection or fire extinguishing systems: Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on November 12, 2001 and implemented on May 1, 2002
GB 4943-2001
-Power supply systems, such as electric generator sets not integrated with the equipment, battery backup systems and transformer building installation wiring;
Devices that do not require power supply.
1.2 Definitions
This standard adopts the following definitions. When the definitions of "voltage" and "current" are used, unless otherwise specified, they refer to effective values. 1.2.1 Equipment electrical ratings
1.2.1. 1 Rated voltage rated voltage The power supply voltage specified by the manufacturer (for three-phase AC power supply, it refers to the line voltage). 1.2.1.2 Rated voltage range rated voltage range The power supply voltage range specified by the manufacturer, expressed by the upper rated voltage and the lower rated voltage. 1.2.1. 3 Rated current rated current The equipment input current specified by the manufacturer. 1.2.1.4 Rated frequency rated frequency The power supply frequency specified by the manufacturer.
1.2.1.5 Rated frequency range ratedfrequencyrenge The power supply frequency range specified by the manufacturer, expressed by the upper rated frequency and the lower rated frequency of the frequency range. 1.2.2 Working conditions
1.2.2.1 Normal load normal load
is as close as possible to the most severe operating mode in normal use as specified in the operating instructions. However, when the actual operating conditions are significantly more severe than the recommended maximum load conditions, a load representing the maximum load conditions that may be encountered should be used. Note: Appendix L lists the normal load conditions for certain types of equipment. 1.2.2.2 Rated operating time réted operating time The operating time specified by the manufacturer for the equipment. 1.2.2.3 Continuous operation Unlimited time operation under normal load conditions. 1.2.2.4 Short-time operation Operation is performed under normal load conditions for a specified period of time. This operation starts when the equipment is in a cold state and there is enough time between each period of operation for the equipment to cool to room temperature. 1.2.2.5 Intermittent operation is performed in a specified series of identical cycles, each cycle consisting of a period of operation under normal load conditions and a period of rest immediately after the equipment is powered off or idling. 1.2.3 Equipment mobility 1.2.3.1 Mobile equipment refers to any of the following equipment: equipment with a mass less than or equal to 18 kg and not fixed, or equipment equipped with rollers, casters or other devices to facilitate the operator to move it as required to complete the intended application. 1.2.3.2 Hand-held equipment Hand-held equipment is a mobile equipment that is held by hand during normal use, or a component of any type of equipment. 1.2.3.3 Tranaportable equipment is a portable equipment that is intended to be carried regularly by the user. NOTE Examples include laptop personal computers, pen-entry computers and their portable accessories such as printers and CD-ROM drives. 1.2.3.4 Stationary equipment Equipment that cannot be moved.
GH 4943—2001
1.2.3.5 Built-in equipment Equipment intended to be installed in a pre-prepared recess, such as in a wall or similar installation. NOTE Usually built-in equipment does not have exterior surfaces on all sides, because some surfaces are protected after installation. 1.2.3.6 Direct plug-in equipment Equipment intended for use without a power cord, where the power plug and equipment exterior form an integral unit and the weight is carried by a wall socket. 1.2.4 Equipment protection categories against electric shock
NOTE: Some information and technical sections of equipment cannot be confirmed as meeting any of the following categories. 1.2.4.］Class I equipment Equipment that achieves protection against electric shock by: - ​​basic insulation and
a connection device is also provided to connect those conductive parts that carry dangerous voltages if the basic insulation fails to the protective earth conductor in the building wiring.
Note! Class 1 equipment may have parts with double insulation and reinforced insulation. 1.2.4.2 Class 1 equipment Equipment that not only relies on basic insulation but also takes additional safety measures (such as equipment with double insulation or reinforced insulation). Such equipment does not rely on protective earthing or protective measures of the installation. 1.2.4.3 Class 1 equipment Equipment that achieves protection against electric shock by relying on power supply from a safety extra low voltage (SELV) circuit and does not generate dangerous voltages. Note: For class ■ equipment, although there is a requirement for protection against electric shock, the other requirements of this standard apply. 1.2.5 Method of connection to the power supply
1.2.5.1 Pluggable equipment type A Item is intended to be connected to the building installation wiring through non-industrial plugs and sockets, or through non-industrial appliance couplers, or through both.
1.2.5.2 Pluggable equipment type B Item is intended to be connected to the building installation wiring through industrial plugs and sockets that comply with GB/T11918 or similar national standards, or through industrial appliance couplers, or through both. 1.2.5.3 Permanently connected equipment Permanently connected equipment Equipment intended to be connected to the building installation wiring by screw terminals or other reliable methods. 1.2.5.4 Detachable power supply cord Detachable power supply cord A cord intended to be connected to the equipment using an appropriate appliance coupler for power supply. 1.2.5.5 Non-detachable power supply cord Non-detachable power supply cord A cord fixed to or assembled with the equipment for power supply. Such cords may be:
Ordinary cord: a cord that can be easily replaced without the use of specially prepared cords or special tools or Special cord: a cord that is specially prepared or requires the use of specially designed tools for replacement, or a cord that cannot be replaced without damaging the equipment.
The term "specially prepared" means a cord that is equipped with an integral cord sheath, using cable ears, forming rings, etc., but does not mean that the wires are re-formed before being connected to the terminal, nor does it mean that the wires are tightened to make the ends of the wires tight. 1.2.6 Enclause
1.2.6.1 Enclasure
A part of an equipment that has one or more of the functions specified in 1.2.6.2, 1.2.6.3 or 1.2.6.4. Note: One type of enclosure can be inside another type of enclosure (e.g. an electrical enclosure inside a fire enclosure, or a fire enclosure inside an electrical enclosure). In addition, one enclosure can provide the functions of multiple types of enclosures (e.g. having both the functions of an electrical enclosure and a fire enclosure).
1.2.6.2 Fire enclosure fire enclosure GB 4943—2001
A component of equipment used to minimize the spread of fire or flames within the equipment. 1.2.6.3 Mechanical enclosure mechanical enclosure A component of equipment used to reduce the risk of injury caused by mechanical hazards and other physical hazards. 1.2.6.4 Electrical enclosure electrical enclosure A component of equipment used to limit contact with components that may carry dangerous voltages or reach dangerous energy levels or components in TNV circuits.
1.2.6.5 Decorative part A component of equipment located outside the enclosure that does not provide safety protection. 1.2.7 Accessibility
1.2.7.1 Operator access area operator access area An area that an operator can access under normal working conditions:
An area that can be accessed without the use of tools, or an area that can be accessed in a predetermined manner, or an area that can be accessed by instructions, regardless of whether or not manual labor is required to access it. In this standard, the terms "access" and "accessible" are defined as above and refer to the operator access area unless otherwise specified. 1.2.7.2 Service access area An area that maintenance personnel must access during maintenance, even when the equipment is powered on, in addition to the operator access area. 1.2.7.3 Restricted access area restricted &ccess location The area of ​​the equipment specified by the following two paragraphs:
- An area accessible only by maintenance personnel or users who are aware of the reasons for the restricted access to the area and the precautions to be taken; and
- An area accessible only by the use of tools, locks and keys or other safety measures and controlled by the responsible authority. Note: Equipment intended to be installed in a restricted contact change area has the same requirements as the operator access area, in addition to meeting the requirements of 1.7.17, 2.1.3 and 4.5.1. 1.2.7.4 Tool
Screwdriver or any other tool that can be used to install and remove screws, latches or similar fasteners. 1.2.7.5 Body
All accessible conductive parts, shaft handles, knobs, clips, etc., and all accessible surfaces of insulating materials after the metal box is attached.
1.2.7.6 Safety interlock devicesafety Interlock is a device that can prevent contact with the hazardous area before the danger is eliminated, or automatically eliminate the hazardous state when a dangerous state is reached. 1.2.8 Circuits and circuit characteristics
1.2.8.1 AC mains supply ACmainssupply External AC power distribution system that supplies power to the equipment. These power supplies include public or dedicated devices, and unless otherwise specified in this standard (such as 1.4.5), they also include equivalent power sources such as motor-driven generators and uninterruptible power supplies. Note: See Appendix V for typical examples of AC power distribution systems. 1.2.8.2 Primary circuit Primary circuit Circuit directly connected to the AC mains supply. Examples include devices connected to the AC mains supply, primary windings of transformers, motors and other loads.
Note: Conductive parts of interconnecting cables may be part of the primary circuit, as described in 1.2.11.6. 1.2.8.3 Secondary circuit Secondary circuit A circuit that is not directly connected to the mains supply but is powered by a transformer, converter or equivalent isolation device located inside the equipment or powered by a battery.
GB 4943—2001
Note: Conductive parts of interconnecting cables may be part of a secondary circuit, as described in 1.2.11.6. 1.2.8.4 Hazardous voltage hazardousvoltage is a voltage exceeding 42.4V AC peak or 60V DC value in a circuit that meets neither the requirements for a current-limited circuit nor the requirements for a TNV circuit.
1.2.8.5 ELV (extra-low voltage) circuit ELV (extra-low voltage) circuit is a secondary circuit in which, under normal operating conditions, the voltage between any two conductors of the circuit or between any conductor and earth (see 1.4.9) does not exceed 42.4V AC peak or 60V DC value; isolated from hazardous voltages by basic insulation, but it meets neither the full requirements for a SELV circuit nor the full requirements for a current-limited circuit. 1.2.8.6 SELV (safety extra-low voltage) circuit SELV (safety extra-law voltage) circuit A secondary circuit that is properly designed and protected so that its voltage value does not exceed a safe value under normal operating conditions and single fault conditions.
1 The voltage limits under normal operating conditions and single fault conditions (see 1.4.14) are specified in 2.2. See also Table 1A. 2 The definition of SELV circuit in this standard differs from the term "SELV system" used in IEC 61140. 1.2.8.7 Limited current circuit A circuit that is properly designed and protected so that the current that can flow from the circuit under normal operating conditions and single fault conditions is a non-hazardous current.
Note: The current limits under normal operating conditions and single fault conditions (see 1.1.14) are specified in 2.4. 1.2.8.8 Hazardous energy level hazardousenergylevel Stored energy level equal to or greater than 20J, or a continuous power level equal to or greater than 240VA at a voltage equal to or greater than 2V.
1.2.8.9 TNV (telecommunication network voltage) circuit TNV ​​(telecommunication network voltage) circuit A circuit in equipment with limited accessible contact areas, which is appropriately designed and protected so that its voltage does not exceed the specified limits under normal operating conditions and single fault conditions (see 1.4.14). TNV circuits can be considered as secondary circuits within the meaning of this standard. Note 1: The voltage limits under normal operating conditions and single fault conditions (see 1.4.14) are specified in 2.3.1, and the accessibility requirements of TNV circuits are specified in 2.1.1.1.
As in 1.2.8.10.1.2.8.11, 1.2.B.12, TNV circuits are divided into TNV-1, TNV-2 and TNV-3 circuits. Note 2: The voltage relationship between SELV circuits and TNV circuits is shown in Table 1A. Note 3: The conductive parts of the interconnecting cable may be part of the TNV circuit as described in 1.2.11.6. Table 1 Voltage range of SELV circuits and TNV circuits Normal operating voltage
Is overvoltage from the communication network possible? Yes
1.2. B.1D TNV-1 circuitTNV-1 circuitwithin SELV limits
TNV-1 circuit
SELV circuit
Exceeding SELV limits but within TNV limits
TNV-3 circuit
TNV-2 circuit
A TNV circuit whose normal operating voltage does not exceed the limits of SELV circuits under normal operating conditions and which may be subject to overvoltages from telecommunication networks on its circuits. 1.2.8.11 TNV-2 circuit TNV-2 circuit Under normal operating conditions, its normal operating voltage exceeds the limit of SELV circuit; and 1) A list of referenced documents is given in Appendix Q "References". GB4943-2001
- TNV circuit that does not withstand overvoltage from the communication network. 1.2.8. 12 TNV-3 circuit TNV-3 circuit - Under normal operating conditions, its normal operating voltage exceeds the limit of SELV circuit; and - TNV circuit that may withstand overvoltage from the communication network on its circuit. 1.2.9 Insulation
1.2. 9. 1 Functional insulation functional Insulation Insulation that is only required for the normal operation of the equipment.
The functional insulation defined does not provide protection against electric shock. However, it can be used to reduce the possibility of ignition and fire hazards. 1.2.9.2 Basic insulation basicinsulation Insulation that provides basic protection against electric shock. 1.2.9.3 Supplementary insulation supplementary insulation Independent insulation applied in addition to basic insulation to reduce the protection against electric shock in the event of basic insulation failure. 1.2.9.4 Double insulation doubleinsulation Insulation consisting of basic insulation plus supplementary insulation. 1.2.9.5 Reinforced insulation rcinforced insulation A single insulation structure that, under the conditions specified in this standard, provides a level of protection against electric shock equivalent to double insulation. Note: The term "continuous insulation structure" does not mean that the insulation must be a uniform whole. This insulation structure can be composed of several insulating layers that cannot be tested separately like supplementary insulation or basic insulation. 1.2.9.6 Working voltage working voltage The highest voltage to which the insulation or component under consideration is subjected or capable of withstanding when the equipment is operating under normal use conditions. 1.2.9.7 Peak working voltage peak working yoltage The highest peak or DC value of the working voltage, including repetitive peak pulse voltages generated within the equipment, but excluding transient values ​​from the outside.
1.2.9.B Required withstand voltage
required withstand voltage
The peak voltage that the insulation under consideration needs to withstand. 1.2.9.9 Nains transient voltage The highest peak voltage expected to appear at the power input end of the equipment, resulting from external transient values ​​on the AC power grid. 1.2.9.10 Telecommunication network transient voltage Telecommunication network transient voltage The highest peak voltage expected to appear at the communication network connection terminals of the equipment, resulting from external transient values ​​on the communication network. 1.2.10 Clearance and creepage distances
1.2.10.1 Clearance
The shortest spatial distance measured between two conductive parts or between a conductive part and the interface of the equipment. 1.2.10.2 Creepage distance The shortest path between two conductive parts or between a conductive part and the protective interface of the equipment measured along the insulating surface. 1.2.10.3 Bounding surface The outer surface of the electrical protective enclosure. For accessible insulating materials, it can be considered as a surface such as a metal foil pressed on the surface of the material. 1.2.11 Components
1.2.11.1 Thermostat
A circulating temperature-sensitive control device that can maintain the temperature between two specific temperature values ​​under normal working conditions. It can be equipped with a device for the operator to set.
1.2.11.2 Temperature limiter A temperature sensitive control device which, during normal operating conditions, keeps the temperature below or above a specified value and which may be fitted with means for operator setting.9 Power supply transient voltage nains transient voltage The highest peak voltage expected to appear at the power input end of the equipment, generated by the external state value on the AC power grid. 1.2.9.10 Telecommunication network transient voltage The highest peak voltage expected to appear at the communication network connection terminal of the equipment, generated by the external state value on the communication network. 1.2.10 Electrical clearance and creepage distance
1.2.10.1 Electrical clearance
The shortest spatial distance measured between two conductive parts or between a conductive part and the interface of the equipment. 1.2.10.2 Creepage distance The shortest path between two conductive parts or between a conductive part and the protective interface of the equipment measured along the insulating surface. 1.2.10.3 Bounding surface The outer surface of an electrical enclosure. For accessible insulating materials, it can be considered as a surface such as a metal foil pressed against the surface of the material. 1.2.11 Components
1.2.11.1 Thermostat
A circulating temperature-sensitive control device that can maintain the temperature between two specific temperature values ​​under normal working conditions. It can be equipped with a device for the operator to set it.
1.2.11.2 Temperature limiter A temperature-sensitive control device that can maintain the temperature below or above a specific temperature value during normal working conditions. It can be equipped with a device for the operator to set it.9 Power supply transient voltage nains transient voltage The highest peak voltage expected to appear at the power input end of the equipment, generated by the external state value on the AC power grid. 1.2.9.10 Telecommunication network transient voltage The highest peak voltage expected to appear at the communication network connection terminal of the equipment, generated by the external state value on the communication network. 1.2.10 Electrical clearance and creepage distance
1.2.10.1 Electrical clearance
The shortest spatial distance measured between two conductive parts or between a conductive part and the interface of the equipment. 1.2.10.2 Creepage distance The shortest path between two conductive parts or between a conductive part and the protective interface of the equipment measured along the insulating surface. 1.2.10.3 Bounding surface The outer surface of an electrical enclosure. For accessible insulating materials, it can be considered as a surface such as a metal foil pressed against the surface of the material. 1.2.11 Components
1.2.11.1 Thermostat
A circulating temperature-sensitive control device that can maintain the temperature between two specific temperature values ​​under normal working conditions. It can be equipped with a device for the operator to set it.
1.2.11.2 Temperature limiter A temperature-sensitive control device that can maintain the temperature below or above a specific temperature value during normal working conditions. It can be equipped with a device for the operator to set it.
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