Some standard content:
National Standard of the People's Republic of China
Installation and operation of residual current operated protective devices
GB13955—92
Installation of leakage current in low-voltage distribution systems Protectors (residual current operated protectors) are one of the effective measures to prevent electric shock accidents, and are also technical measures to prevent electrical fires and damage to electrical equipment caused by leakage. However, after installing the leakage protector, prevention should still be the main focus, and other technical measures should be taken to prevent electric shock and damage to electrical equipment. 1 Subject content and scope of application
This standard specifies the relevant requirements for the correct selection, installation, use of current-operated leakage protectors and their operation and management. This standard is applicable to power supply systems with an operating voltage of AC 50Hz and a 220/380V power supply with the neutral point directly grounded. The leakage protector referred to in this standard refers to a leakage protection device that can automatically cut off the power supply or alarm when the leakage current in the circuit exceeds the allowable value, including various types of leakage circuit breakers, plugs (seats) with leakage protection, leakage protection devices, etc. Protection relays, leakage fire alarms, combined electrical appliances with leakage protection functions, etc.
2 cited standards
GB3787 Safety technical regulations for the management, use, inspection and maintenance of hand-held power tools GB6829 Leakage current action protector
GB4776 Electrical safety terminology
GB9706.1 Medical electrical equipment Part 1: General safety requirements JBI284 low-voltage circuit breaker
3 Terms
3.1 Direct contact direct contact
Contact between human body, domestic animals and live conductors. 3.2 Indirect contact indirect contact is the contact between human body, livestock and exposed conductive parts of equipment that becomes live under fault conditions. 3.3 Impulse voltage non-operating type residual current leakage protector impulse voltage non-operating type residual current operated protective devices
When the leakage protector is in a closed circuit state, it does not operate under the specified impulse voltage. 3.4 Main protection main protection
The leakage protector is installed at the power supply end or incoming line end of the low-voltage power grid to achieve overall protection of the network to which it belongs. 3.5 Graded selective protection selective sectionprotection leakage protectors are respectively installed at the power supply end, branch (trunk) line, and load end, forming a two-level or above leakage protection system, and the leakage action current values ??and action times of the leakage protectors at each level are Coordinate and cooperate to achieve selective hierarchical protection. 3.6 Combined leakage protector assemble type residual current operated protective devices National Technical Supervision Kitchen approved 20 on 1992-12-19 | | tt | Application
4.1 Protection against direct contact
4.1.1 The leakage protector is only used as an additional protection for the basic protection measures in contact protection. 4.1.2 When used for direct contact electric shock protection, a high-sensitivity, fast-acting leakage protector should be selected. The operating current does not exceed 30mA.
4.2 Indirect contact protection
4.2.1 Indirect contact electric shock protection mainly adopts the protection method of automatically cutting off the power supply to prevent the exposed conductive parts of electrical equipment from continuing to be dangerous when a ground fault occurs Voltage may cause electric shock hazard. 4.2.2 In indirect contact protection, when using a leakage protector that automatically cuts off the power supply, it should be correctly matched with the system grounding type of the power grid.
4.2.3 When used for indirect contact electric shock protection, the correct use of leakage protectors in various system grounding types (see Appendix A): 4.2.3.1TN system
a. In TN system When an insulation damage fault occurs in the circuit and the fault current value is less than the operating current value of the over-current protection device, a leakage protector must be installed;
b. In a TN system using leakage protectors, the exposed conductive parts of the electrical equipment used can be separately grounded according to the specific conditions of the electric shock protection measures to form a local TT system. 4.2.3.2TT system
For the electrical lines or electrical equipment of the TT system, priority should be given to installing leakage protectors as a protective measure against electric shock. 4.3 Protection against electrical fires
4.3.1 In order to prevent electrical fires caused by insulation damage to electrical equipment and circuits, it should be installed that can send out audible and visual signal alarms or automatically cut off the power supply when the leakage current exceeds a predetermined value. leakage protector. 4.3.2 The relationship between leakage protectors, leakage relays or alarm devices installed to prevent electrical fires and terminal protection should form hierarchical protection.
4.4 Graded Protection
4.4.1 In order to reduce the scope of power outages caused by personal electric shock and ground fault cutting off the power supply, the graded protection of leakage protectors is generally divided into two levels. The rated leakage operating current and operating time of the two-stage leakage protector should be coordinated. 4.4.2 The leakage protector installed at the power supply end should be a low-sensitivity delay type leakage protector. 4.5 Equipment and places where leakage circuit breakers must be installed belong to mobile electrical equipment and handheld power tools, a.
b.
Electrical appliances installed in places with harsh environments such as humid and highly corrosive environments Equipment; c.
d.
e.
f.
g.
h.
i
Electrical construction machinery and equipment at construction sites; electrical equipment for temporary power use,
Socket circuits in guest rooms of hotels, restaurants and guest houses; Socket circuits in government agencies, schools, enterprises, residences and other buildings: swimming pools , underwater lighting equipment in fountains and baths; power supply lines and equipment installed in the water; electrical medical equipment in hospitals that are in direct contact with the human body 2; other places where leakage protectors need to be installed. j.
Note: 1) Electrical products can be divided into four categories: 0, I, I, and " according to the insulation level of protection against electric shock. Category 1 is a product whose protection against electric shock not only relies on the basic insulation of the equipment, but also includes An additional safety precaution is to connect potentially accessible conductive parts to 21
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GB13955-92
protective wires in the installed fixed wiring. Connected so that accessible conductive parts do not become electrified in the event of damage to the basic insulation. 2) Class H medical equipment according to GB9706.1. 4.6 Application of alarm-type leakage protectors
Electrical devices or places that will cause accidents or significant economic losses when power leakage occurs should be installed with alarm-type leakage protectors, such as:
passage lighting and emergency lighting in public places; a.||tt| |Elevators for fire protection and equipment to ensure the safety of public places; b.
c.
Power supply for fire-fighting equipment, such as fire alarm devices, fire pumps, fire passage lighting, etc.; used for anti-theft alarms power supply;
d.
e.
Other special equipment and places that do not allow power outages. 4.7 Equipment that does not need to be equipped with leakage protectors
use safe voltage for power supply. Electrical equipment: a.
b.
Electrical equipment with double insulation or reinforced insulation used under general environmental conditions; c.
Electrical equipment powered by an isolation transformer: d ．
Electrical equipment used in places where ungrounded local equipotential bonding safety measures are adopted: electrical equipment in places where there is no indirect contact with electric shock hazards e.
5 Selection of leakage protectors.
5.1 The technical conditions of the leakage protector should comply with the relevant regulations of GB6829 and have the national certification mark. Its technical rating should match the technical parameters of the protected line or equipment (see Appendix B). Use a leakage protector as the power supply method of the equipment. a. Electrical equipment powered by a single-phase 220V power supply should use a two-pole two-wire or single-pole two-wire leakage protector; b.Electrical equipment powered by a three-phase three-wire 380V power supply should use a three-pole leakage protector; c. Electrical equipment powered by three-phase four-wire 380V power supply, or circuits shared by single-phase equipment and three-phase equipment, should use three-pole four-wire type or four-pole four-wire type electrical protectors.
5.3 Select the rated leakage operating current of the leakage protector based on the normal leakage current of the electrical circuit. 5.3.1 When selecting the rated leakage operating current value of the leakage protector, the normal leakage current value that may occur in the protected line and equipment should be fully considered. If necessary, the leakage current value of the protected line or equipment can be obtained through actual measurement. 5.3.2 The rated leakage non-operating current of the selected leakage protector should not be less than 2 times the maximum normal leakage current of the electrical lines and equipment
5.4 Select the leakage protector for leakage protection according to the environmental requirements of the electrical equipment The protection level of the device should be adapted to the environmental conditions of use; a.
b.
For electrical equipment with large power supply voltage deviations, electromagnetic leakage protectors should be preferred: c.||tt| |Electrical equipment in high-temperature or ultra-low-temperature environments should give priority to electromagnetic leakage protectors; electrical equipment in areas with frequent lightning activity should use impulse voltage non-operating leakage protectors, d.
Installed in flammable, For leakage protectors in harsh environments such as explosive, humid or corrosive gases, leakage protectors with special protection conditions should be selected according to relevant standards, otherwise corresponding protective measures should be taken. 5.5 Selection of operating parameters of leakage protectors 5.5.1 For hand-held power tools, mobile appliances, and household appliance socket circuit equipment, priority should be given to fast-acting leakage protectors with a rated leakage operating current of no more than 30mA.
5.5.2 A single motor equipment can use a leakage protector with a rated leakage action current of 30mA and above and a fast action of below 100mA.
5.5.3 For total protection of multiple devices, a fast-acting leakage protector with a rated leakage operating current of 100mA or above should be selected. 22
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GB13955-92
5.6 For special loads and places, leakage protectors should be selected according to their characteristics 5.6.1 Hospitals When installing a leakage protector on medical electrical equipment, a leakage protector with a rated leakage operating current of 10mA and fast action should be selected.
5.6.2 Electrical equipment installed in humid places should use leakage protectors with a rated leakage operating current of 15~30mA and fast action. 5.6.3 For lighting circuits installed in swimming pools, fountains, water playgrounds, and bathrooms, fast-acting leakage protectors with a rated leakage operating current of 10 mA should be used.
5.6.4 When working on metal objects, operating hand-held power tools or portable lights, a leakage protector with a rated leakage operating current of 10mA and fast action should be selected.
5.6.5 Electrical equipment connected to outdoor overhead lines should use impulse voltage non-operating leakage protectors. 5.6.6 For general protection with overhead lines, leakage protectors with medium or low sensitivity and delayed action should be selected. 6 Installation of leakage protectors
6.1 Installation requirements of leakage protectors
6.1.1 The installation of leakage protectors should comply with the requirements of the manufacturer's product instructions. 6.1.2 The installation of the leakage protector should fully consider the power supply line, power supply method, power supply voltage and system grounding type. 6.1.3 The rated voltage, rated current, short-circuit breaking capacity, rated leakage operating current, and breaking time of the leakage protector should meet the requirements of the protected power supply line and electrical equipment.
6.1.4 Installation and wiring of the leakage protector It should be correct. The correct wiring method of the leakage protector in the single-phase, three-phase three-wire, and three-phase four-wire power supply systems with different system grounding forms is as shown in Table 1. 6.2 Requirements of the leakage protector on the low-voltage power grid 6.2. Load of the leakage protector The neutral line on the side must not be shared with other circuits. 6.2.2 When the electrical equipment is equipped with a high-sensitivity leakage protector, the grounding resistance of the separate grounding device of the electrical equipment can be relaxed to a maximum of 500Ω, but the expected contact voltage must be limited to the allowable range. 6.2.3 The leakage current of lines and electrical equipment protected by leakage protectors must be controlled within the allowable range and must meet the provisions of Section 5.3.2 of this standard. When the leakage current is greater than the allowable value, the power supply line with good insulation must be replaced. 6.2.4 The insulation resistance value of motors and other electrical equipment installed with leakage protectors during normal operation should not be less than 0.5M2. 6.3 Construction requirements for installing leakage protectors
6.3.1 The leakage protector is marked with the load side When connecting to the power supply side, the wiring should be installed according to regulations, and reverse connection is not allowed. 6.3.2 When installing a leakage protector with short-circuit protection, it is necessary to ensure that there is sufficient flying distance in the arc ejection direction. The arcing distance shall be in accordance with the regulations of the leakage protector manufacturer.
6.3.3 The control circuit connected externally to the combined leakage protector shall use copper wires, and its cross-sectional area shall not be less than 1.5mm. 6.3.4 After installing the leakage protector, the grounding protection measures for low-voltage power supply lines and electrical equipment cannot be removed, but inspection and adjustment should be carried out according to the requirements in 6.1.4 and 6.2.1. 6.3.5 After the leakage protector is installed, the test button should be operated to check the working characteristics of the leakage protector, and it is allowed to be put into use only after confirming that it can operate normally.
6.3.6 Inspection items after installation of leakage protector a. Use the test button to test 3 times and it should operate correctly; b. Open and close the switch with load three times, and there should be no malfunction. 6.3.7 The neutral line and the protective line must be strictly distinguished during installation. The neutral line of a three-pole four-wire or four-pole leakage protector should be connected to the leakage protector. The neutral wire passing through the leakage protector shall not be used as a protective wire, and shall not be repeatedly grounded or connected to exposed conductive parts of the equipment. The protection wire must not be connected to the leakage protection device.
6.3.8 The installation of leakage protectors must be carried out by electricians who have passed technical training and assessment. 23
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7 Operation and management of leakage protectors
GB 13955--92
7.1 After the leakage protector is put into operation, the user should establish an operation record (see Appendix C for the operation record format) and establish a corresponding management system
7.2 After the leakage protector is put into operation, it must be in the energized state every month. Press the test button to check whether the leakage protector operates reliably.
7.3 After lightning strikes or other unknown reasons cause the leakage protector to operate, check the leakage protector. The operating characteristics and changes during operation should be tested regularly. Characteristic test items:
Test leakage operating current value;
a.
b Test leakage without action. Current value;
c.
Test breaking time.
7.5 Before using the leakage protector that has been taken out of operation, press 7.The items specified in Article 4 shall be tested for operational characteristics. 7.6 When conducting the operating characteristics test of the leakage protector, special testing instruments that have been tested and qualified by the relevant national departments should be used. It is strictly prohibited to use the test method of directly touching the grounding device with the phase line. 7.7 After the leakage protector operates, if the cause of the accident is not found after inspection, it is allowed to send power once. If it operates again, the cause should be found out and the fault should be found out. If necessary, its operating characteristics should be tested, and power should not be forced to be sent continuously. Unless the inspection confirms that the leakage protector itself is faulty, it is strictly prohibited to remove the leakage protector without permission and force the power supply. 7.8 Regularly analyze the operation of leakage protectors and replace faulty leakage protectors in a timely manner. 7.9 The operating characteristics of the leakage protector are set by the manufacturer. They should be used according to the product instructions and should not be changed at will during use. 7.10 The maintenance of the leakage protector should be carried out by professionals. If any abnormality occurs during operation, an electrician should be consulted to avoid expanding the scope of the accident. 7.11 If an electric shock casualty occurs within the protection range of the leakage protector, the operation of the leakage protector should be checked and the reasons for failure to protect should be analyzed. The site should be protected before investigation, and the leakage protector must not be dismantled. 7.12 In addition to regular testing according to the leakage protection characteristics of the leakage protector used, the circuit breaker part should be regularly inspected and maintained according to the relevant requirements of low-voltage electrical appliances.
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A1TN system
GB 13955-92
Appendix A
Types of system grounding
(reference part)
The power system has one point directly grounded, and the exposed conductive parts of the electrical device are connected to the ground point through a protective wire. TN system can be divided into:
TN-S system: the neutral line and protective line of the entire system are separated (Figure A1); TN-C system: the neutral line and protective line of the entire system are combined (Figure A2); TN-CS system: The neutral line and protection line of some lines in the system are integrated (Figure A3).
LO
Lo
Lo
NO
PEQ
Power system grounding point
Exposed conductive parts|| tt||Figure A1TN-S system
L,o
Lo
L,o
PENO
=
Power system connection Location
Exposed conductive part
Picture A2TN-C system
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LO
L,o
Power system grounding point
A2 TT system
GB 13955-92
Exposed Conductive parts
Figure A3TN-CS system
PE
The power system has one point that is directly grounded, and the exposed conductive parts of the electrical equipment are connected to the ground point of the power system through a protective grounding wire. Ground electrode (Figure A4).
LO
LO
L,O
NO
Power system ground point
A3IT system
Exposed conductive Part
PE
Lo
L:O
LO
NO
PE
Power system grounding point|| tt||Figure A4TT system
b
Exposed conductive parts
There is no direct connection between the power system and the earth, and the exposed conductive parts of the electrical device pass through the protective grounding wire and grounding electrode connection (Figure A5).
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