【 Weak current College 】 electrical equipment safety testing-Power By 【 China power house network 】

Analysis of electric fire
Electrical fires are caused by the fire source of electric energy. Its direct due mainly to the leakage current, short circuit, overload, bad, overload, arc, EDM, etc, resulting in high-temperature heating and ignite combustibles causing fire around.
◆ Leakage: wire or the scaffold insulation capacity, that conductors or between a conductor and the Earth between trace of current leakage through the EDM can be a fire with fire;
◆ Short circuit: electrical lines, for various reasons, the potential of different touches or touch two points to produce current suddenly increasing phenomenon. Due to the short circuit current is large, in the short point, it is easy to produce strong EDM and wire arc, and melting of metal conductors and denudation defect marks this strong short circuit arc and melting-temperature metals can result in the burning of combustible material. Through short circuit current of the wire, because of the very short heating value is very large, even cause short circuit of rapid combustion of the wire insulation, and can cause conductors near fuel combustion, resulting in a fire;
◆ Overload: guidelines adopted by the current more than security current value. Because the wire itself has a resistance, current will flow through the electrical heating, heating value, the higher the temperature of the wire insulation. Once the insulated conductors of the temperature exceeds the maximum allowable working temperature, the wire's insulation will accelerate ageing, even burning, fire accidents;
◆ Contact resistance is too large: on power cables and power cords and switches, protective devices and larger electrical devices connected place, due to poor contact, contact local resistance is too large. In a large current through the electrical circuit, and in case of contact resistance is too large, in their local scope will produce great heat, you can make the metal discoloration even melting, and cause electrical wiring insulation, nearby combustibles and accumulation of flammable dust ignition, start a fire;
◆ Sparks and arcing. EDM is the result of the discharge electrodes, arc is a large concentration of EDM. Arc of the temperature should be above EDM 3000qC and arc easily combustible combustion, fire or explosion.
Several electrical devices running
◆ Good running condition. Various run technical parameters (voltage, current, frequency, etc.) to normal, warm parts of temperature and temperature rise in the technical specification of the allowable range, no spark and arc phenomena;
◆ There electrical accident status. Basic technical parameters properly, heating parts of a slight increase of temperature rise, over technical specifications stipulate the allowed values for the arc-discharge and does not appear, but no fuel around electrical equipment. It may endanger the physical safety or cause electrical equipment and wiring faults;
◆ Electric fire hazard exists. Basic technical parameters properly, but the heating temperature and temperature rise of exceeds the allowed values for technical specifications, even a spark and arc phenomena and electrical devices around there combustibles. In this case, the electric fire in three basic conditions were all met.
Electric fire accident can be divided into hot-risk and discharge. Hot-risk of basic characteristics is the electrical equipment or lines of high-temperature heating parts generate an exception, thereby igniting electrical equipment and wiring of insulating materials and surrounding fuel; discharge characteristics of vulnerability is electrical equipment and wiring insulation damage, the gap and surface free discharge and Corona, serious would create insulation breakdown and flashover, performance for the EDM and arc. Electrical facility security detection technology
Guarantee electrical appliance running, you can use infrared temperature measurement technology, ultrasonic detection technology combined with electrical measurement technique to detect the existing problems.
Infrared temperature measurement technology primarily to detect overheating of electric fire hazard. It leverages optics, electronics conversion system receives the object of radiant energy, into temperature and displayed, is a non-contact temperature measurement method. It is convenient to use, widely used, the current widespread use of a temperature, hot TV and thermal imager.
Ultrasonic detection primarily testing discharge electrical fire hazard. Electrical equipment and wiring for insulation against moisture, decay, caused by mechanical operation of electric arc or spark and leaking oil in electrical equipment, ultrasonic detection will detect abnormal sound, the abnormal sound corresponding arc-discharge and frequency or wavelength, so you can identify the electrical fire hazard exists.
Electrical measuring instruments, including voltage, current, resistance, resistance, current harmonic content and true RMS, etc. Electrical facility security detection range □ variable power distribution unit □ high and low voltage electrical line □ motors, welding machines, transformers □ □ LV electrical switches and electrical lighting decoration □ electric equipment (including the central air conditioning equipment) □ control electrical and fire protection of electrical □ electrical installations □ facilities for temporary power electrical appliance □ grounding □ explosion-proof and fire electric device □ special environment of electrical equipment and lighting □ other electrical equipment