Article 16 of the Fire Protection Law stipulates that building fire protection facilities should be comprehensively inspected at least once a year to ensure that they are in good condition and effective, and the inspection records should be complete and accurate and filed for future reference; Article 27 stipulates that the quality of electrical products and gas appliances must meet the national standards or industry standards, and the installation and use of electrical products and gas appliances, as well as the design and laying of lines and pipelines must meet the national technical regulations on fire safety. This requires intermediary agencies to provide intermediary testing services, thus providing legal protection for the emergence of electrical fire safety testing companies.
Specific differences between building fire protection facilities and electrical fire safety detection
Electrical fire safety inspection and building fire control facilities inspection
Electrical fire safety inspection is an important aspect of fire safety inspection. The original methods such as eyes, hands and nose are not enough for the fire safety inspection of electrical circuits and equipment. Advanced instruments and equipment and modern detection technology must be used.
1 Purpose of electrical fire safety inspection
Electrical fire safety inspection is an important part of electrical fire safety inspection. Its purposes are: first, to prevent fire and explosion accidents caused by various faults and improper operation of electrical systems and electrical equipment; The second is to prevent electric shock accidents and casualties. The electrical fire safety test shall be approved by the tester and the tested party. Before the national laws and regulations are not clearly defined, electrical fire safety testing should not become a difficult work to share. In the process of fire safety inspection, the public security fire department uses necessary instruments to carry out safety inspection on electrical systems and equipment, which is a specific administrative act of implementing fire supervision on enterprises according to the Fire Protection Law of People's Republic of China (PRC). It is not for the purpose of charging and profit, and no extra fees should be charged.
2 detection range
The scope of electrical fire safety inspection is mainly aimed at power users, that is, newly built, rebuilt and expanded industrial and civil buildings with voltage levels below 10 kV and 10 kV. The detection of high-voltage and ultra-high-voltage power supply systems above 10kV shall be carried out by the power system. In addition, the electrical fire safety inspection in explosive dangerous places should be cautious, and companies that have not been trained in fire prevention and explosion-proof professional knowledge and explosion-proof testing instruments and equipment should not undertake this inspection.
Specific scope of electrical fire safety inspection:
(1) Substation, including: oil-immersed power transformer, dry-type power transformer, high-voltage power distribution device, low-voltage power distribution device, power capacitor and low-voltage electrical appliances (such as low-voltage circuit breaker, low-voltage disconnector, leakage protector, distribution box and switch box);
(2) Indoor low-voltage distribution lines, including indoor wiring, conductor connection, conductor connection with equipment, conductor insulation strength, power cable lines, etc.
(3) Lighting devices, switches and sockets;
(4) General low-voltage electrical equipment, such as motors, rectification equipment and other small electrical equipment;
(5) Grounding and equipotential connection.
3 test requirements
Before electrical fire safety inspection, first check the environmental conditions (such as high temperature, humidity, dusty, corrosive gas, etc.). ) the electrical wiring and equipment are suitable for the specified working conditions. Electrical fire detection should be carried out after the electrical lines and equipment have been running under load for a certain period of time and entered the normal thermal stable working state. According to the requirements of fire prevention work, electrical fire safety inspection shall be carried out in time in the following situations:
(1) Before the completion acceptance of new construction, reconstruction, expansion and decoration projects;
(two) before the use and opening of dance halls, theaters, hotels, restaurants, shopping malls and other public gathering places;
(3) before holding large-scale activities (such as large-scale literary evening, lantern festival, fireworks evening, large-scale exhibition, etc.);
(4) On the eve of thunderstorm season;
(5) On the eve of electricity consumption peak;
(6) Before using new large-scale electrical equipment;
(7) After electrical failure and fire accident.
4 the content of the test
(1) temperature. Under abnormal conditions, abnormal temperature of electrical circuits and equipment is inevitable. Therefore, temperature detection is an important aspect of electrical fire safety detection.
(2) Insulation resistance. The insulation resistance value reflects the insulation capacity of electrical lines and equipment, and the decrease of insulation resistance value indicates that insulation aging, overheating, short circuit and other faults occur, which is easy to cause fire accidents.
(3) Grounding resistance. Grounding of electrical devices is divided into protective grounding and functional grounding. In order to ensure the normal operation of electrical equipment, there must be a good grounding system. Grounding resistance is an important index reflecting the quality of grounding system, especially for lightning protection, explosion protection and anti-static places.
(4) Harmonic component and neutral line overload current. The neutral current consists of three-phase unbalanced load current and harmonic current of cubic and odd nonlinear load current. When the cross section of the neutral line is the same as the cross section of the phase line, the effective value of the neutral line current should not exceed the phase line current; When the cross section of the neutral line is twice that of the phase line, the effective value of the neutral line current should not exceed twice that of the phase line current.
(5) Spark discharge. Spark discharge is the fire source condition of fire, and accurately grasping the position of spark discharge is the premise of preventing electrical fire. Ultrasonic leak detector can detect spark discharge in electrical equipment.
5. Detection methods and related instruments and equipment
Electrical fire safety detection is a highly technical work, which needs to be completed by advanced technology and methods. At present, electrical fire detection generally adopts infrared temperature measurement technology, infrared thermal imaging technology, ultrasonic detection technology and harmonic detection technology, combined with professional electrician measurement technology. The main instruments and equipment used are VC 15A, VC 15B fire-fighting electrical detection box, VC- 12 building fire-fighting facilities detection box, infrared thermometer, infrared thermal imager and ultrasonic leak detector. Common electrical measuring instruments and tools include voltage, current, insulation resistance, grounding resistance and current harmonics.
1. Using infrared thermometer, the temperature of abnormal heating parts, the field temperature of electric contact parts and hot surface parts can be tested, and the normal temperature rise or failure of equipment can be judged by comparison method. Commonly used models are F68, F572, KR90, etc.
2. The infrared thermal imager can automatically scan, check the temperature, identify the temperature difference change, and determine the hidden position and nature of the fire. It can take thermal images of the heating parts of key electrical circuits and equipment, analyze and process the temperature field distribution of the thermal images by computer software, and issue thermal image reports for inspection and analysis. Commonly used models are IRI 10 1 1, IRI40 10, etc.
3. Use the ultrasonic leak detector to detect the electrical equipment that causes spark discharge leakage due to high resistance grounding, virtual wire connection, insulation damage and leakage, poor connector contact, lines in ceiling, lines in concrete, buried cable lines or local electromagnetic field rise, and capture the ultrasonic waves and ultrasonic signals of spark discharge, and convert them into sounds that can be heard by human ears, thus achieving the purpose of accurately diagnosing the hidden state of spark discharge leakage. There are mainly ULTRAPROBE2000 and ULTRAPROBE500 models produced by UE company in the United States, and UT 100K is mainly selected for domestic models, with lower price.
4. The clamp grounding resistance tester can accurately measure the grounding resistance of lightning protection, static electricity and electrical protection, without piling grounding. Japan made 4200 French made CA64 15.
5. Digital insulation resistance tester can measure the aging degree and voltage insulation resistance of wire and cable insulation layer. Japanese models 3005 and 3007, domestic VC60, etc.
6. The high-voltage electroscope can measure the voltage of 0- 10 kV for the safety protection of testers.
7. The socket detector can measure the "left zero and right fire" wiring and grounding protection line of the socket without disassembling the socket, and can also simulate the test of 30mA leakage circuit breaker, which is convenient and accurate.
8. Testing voltage, current, frequency and other related parameters with true rms AC /DC clamp meter and common clamp ammeter requires high test resolution, high test precision and many test functions. This instrument has the characteristics of large jaw diameter, high measurement resolution and accuracy, accurate measurement of small current and inrush current, etc. At the same time, the humanized design of the clamp table is very suitable for use in narrow spaces. It can accurately and quickly measure the load current value of lines and electrical equipment.
9. The leakage switch tester can test DC sensitive circuit breakers and has three indicator lights to check the circuit. Whether the phase angle switches of 0 and 180 degrees are consistent with the quick test readings, the trip time will be displayed on the digital screen. /
10. The pipeline fault tracker can detect and track wires, cables and any metal conductors in walls or floors. And find the short circuit or open circuit fault position of wires and cables. It can also work without power supply. If multiple signal transmitters are used, the line can also be divided under the condition of power failure or uninterrupted power supply. The main models are VC 15B.
1 1. Three-phase power harmonic/balance analyzer is mainly used to measure and analyze the load and characteristics of electrical equipment. Liquid crystal display 10 sets of measurement data, which can be connected with four current clamps to measure three-phase and four-wire, 1PW, 1PW, 3P3W2M and 3P4W power measurement. True rms measurement. Power KW, KVAR, KVA, PF, θ, Hz and energy KWh, KVARh and KVAh measurement, automatic continuous data recording (5 12KB memory, 20,000 records), settable recording start and end time, RS-232 interface transmission, with three-phase voltage and current waveform display and harmonic analysis functions. Commonly used models are P 102 and FR3600 of Beijing Xinyu Shengli Instrument.
12. As one of the necessary detection tools in daily detection, digital multimeter is mainly used to detect voltage, current, frequency and other related parameters, and its resolution is required to reach at least 4 1/2 bits (19999 words). At present, the resolution of this multimeter commonly used by maintenance personnel can reach 4 4/5 bits (50,000 words), which can fully meet the requirements of the specification for test accuracy. At the same time, this multimeter has the characteristics of good anti-fall, anti-burn, anti-magnetism, anti-sputtering, intelligent alarm and so on, which is very suitable for testing field.
13. Induction electric probe. The induction probe is mainly used to check the live part of the live bus. At present, the inductive electric probe commonly used by inspectors adopts inductive detection without physical contact, which greatly ensures the personal safety of maintenance personnel. American F- 1AC (low voltage) /AC (high voltage) induction probe.
14. The phase sequence tester is mainly used to test the phase sequence of three-phase alternating current. This kind of phase sequence table is portable and simple to test, which is very suitable for field test. At present, testers usually use Japanese 8030 and VC850 phase sequence tables.
15. smoke detector function tester (smoke intensity) and temperature detector function tester (temperature gun): mainly used to generate simulated fire signals and test the functions of automatic fire alarm and linkage control system. Commonly used models are Beijing Xinyu Shengli Instrument VC-08 and VC-3.5.
16. Anemometer: measure the wind speed and temperature of the smoke outlet and air supply outlet.
17. Illuminator: measure the illuminance of various occasions and the brightness of emergency indicator light to judge the requirements of evacuation lighting in case of fire.
18. sound level meter: measure the noise level in various places.
19. Thermohygrometer: measure the ambient temperature and humidity, and monitor the test environment.
20. Combustible gas detector: used to continuously detect the concentration of flammable gases such as alkanes, alcohols and organic volatiles in the working environment.
2 1. Fire-retardant coating thickness gauge: to detect the thickness of fire-retardant coating of steel structure.
22. Domestic series of commonly used instruments (tools) are used for auxiliary detection.
The digital image and computer information processing system introduced and developed by our center, using the above instruments and equipment for comprehensive detection, is the leading professional detection and analysis system for electrical fire prevention in China at present, which can fully meet the technical requirements of fire protection facilities inspection and electrical fire safety inspection in general places.
6 detection standard
The basis of electrical fire safety inspection should be current national or local relevant technical standards and specifications, such as Beijing Technical Specification for Electrical Fire Detection DB11065-2000, Basic Standard for Low-voltage Electrical Appliances GB 1497- 1985, Safety Requirements and Testing of Lamps. The criteria for judging low-voltage distribution should be based on specific regulations. For indoor low-voltage distribution lines, the insulation resistance between the phase line of each branch insulated conductor and the ground should not be less than 0.5 MD, and the maximum allowable temperature of the core and contact for long-term operation is 70? C, rubber line is 65? C.
Electrical fire safety detection is a complex work, which is highly technical and policy-oriented. To do a good job in electrical fire safety inspection, we should not only strengthen the management of inspection work and formulate unified inspection regulations, but also study and formulate relevant policies, such as formulating clear fire risk judgment standards, that is, solving what is a major electrical fire hazard and what should stop using electricity (work). When necessary, the fire department should actively cooperate with the electric power department to make the electrical fire safety inspection work develop in a long-term and standardized way.