Leakage protection plugs  [2015-3-13]

Do you want to install on residential electricity leakage switch, there are several erroneous views, GFCI may malfunction, causing power outages, and therefore do not install the GFCI; as long as the ground reliable, you can not install the GFCI, has installed a GFCI, electrical housing of the device connected to an ungrounded not matter; GFCI already installed, then the electrical equipment enclosure with the water pipe connected to how authentic ......

Leakage current device called leakage protection, also known as leakage protection switch, is mainly used in the event of equipment failure and leakage of deadly danger of personal electric shock protection.

Leakage protection in the field of electrical safety is still a relatively new technology. The last thirty years, with the development of electronic technology, high sensitivity, fast action leakage protection device was a great development. Germany, France, Britain, the United States, Japan and other countries and the International Electrotechnical Commission has established and have revised the leakage protection device product standards and their associated standards and regulations. In our country many leakage protection device manufacturers, product variety, the state developed a national standard "leakage current device" (GB6829-86), the standard leakage protection characteristics, classification, working conditions and installation conditions, structure and aspects of performance requirements, test methods, inspection rules made clear.

First, the leakage protection principles and constitution

Leakage protection with high sensitivity and fast action in response shock and leakage protection, which is the other protective devices, such as fuses, automatic switches, etc. can not be compared. Automatic switch and fuse the normal load current through their actions to protect the value to avoid the normal load current setting, so their main role is to cut off the system phase fault (some automatic switch also has overload protection ). The leakage protection system is the use of residual current response and action, normal operation residual current system is almost zero, so it moves tuning setting values can be very small (typically mA level), when the system generates physical shock or equipment When live shell, larger residual current, leakage protection is detected and processed by the residual current operated reliably, cut off the power.

So how leakage protection protects effect?

We know that when the electrical equipment leakage, will show abnormal current or voltage signal by detecting leakage protection, to handle this abnormal current or voltage signal, prompting the executing agency action. We called current leakage protection device according to the fault current leakage protection action, called voltage-leakage protection leakage protection fault voltage according to the action. Since the voltage leakage protector complex structure, the operating characteristics of outside interference, poor stability, high manufacturing costs, has been basically eliminated. Current leakage protection of domestic and foreign research and application are current-leakage protection for dominance.

Current-leakage protection is part of the circuit in the zero sequence current (often referred to as residual current) signal as the action, and many electronic components as an intermediate body, high sensitivity, fully functional, so this protection devices are more widely applications.

Second, leakage protection classification

Leakage protection can protect their functional, structural characteristics, installation, operation mode, the number of poles and lines, movement sensitivity classification, where the main function and purpose of their protection classification is described, and can be divided into leakage protection relays, leakage protection and leakage protection switch socket three.

1. leakage protection relay refers to a leakage current detection and judgment of functionality without having leakage protection devices and turn off the main circuit functions. Leakage protection relay by zero sequence transformer, auxiliary contacts release composition and output signals. It can be used with large current automatic switch, as a low-voltage grid of the total leakage protection or trunk road, grounded or insulated surveillance protection.

When the main circuit leakage current, since the auxiliary contacts and main circuit switch separate series into a loop trip. So turn on the auxiliary contacts separate release and disconnect the air switch, AC contactor, etc., to make it out of the gate, cut off the main circuit. Auxiliary contacts can also be turned audible signal devices emit an alarm signal leakage, reflecting insulation condition of the line.

2. leakage protection switch means not only that it, like other main circuit breaker can be turned on or off, and has a current leakage detection and judgment function, when the main circuit in the event of leakage or insulation damage, the leakage protection switch according to Analyzing the results of the main circuit switching element is turned on or off. It fuses with thermal relay function may constitute a complete low-voltage switchgear components.

This form is currently the most widely used device leakage protection, leakage protection switch on the market according to the function commonly used are the following categories:

1. Only power-off function with leakage protection, protection devices must cooperate with fuses, thermal relays, overcurrent relays, etc. use.

2. Simultaneously with overload protection.

3. both overload and short circuit protection.

4. At the same time short-circuit protection.

5. At the same time has a short circuit, overload, leakage, overvoltage, undervoltage function.

3. Leakage protection socket refers to a leakage current detection and judgment and to cut off the circuit outlet. 20A rated current is generally less leakage current 6 ~ 30mA, high sensitivity, commonly used in portable electric power tools and portable electrical equipment protection and family, schools and other civilian sites.

Third, the selection principle leakage protection

Countries in order to regulate the proper use of leakage protection, have issued a series of standards and regulations "leakage protection safety monitoring requirements" (Lao Zi (No. 1999) 16) and the "leakage protector installation and operation (GB13955-92), etc. .

Based on these standards and regulations, we follow the main principles of selection leakage protection should be in:

1. Purchase leakage protection when buying products with the production of qualified manufacturers and product quality inspection. Here to remind everyone: Currently on the market there are a lot of leakage protection is unqualified. October 28, 2002, AQSIQ announced leakage protection product quality sampling results, about 20% of product failure, the main problem is: some can not properly breaking short-circuit current, eliminate fire hazards; some do not play Protective effects of the physical shock; there should not be a trip to trip some time, affecting the normal electricity.

2. should be based on the scope of protection, personal safety equipment, and environmental requirements to determine leakage protection of the supply voltage, current, leakage current and operating time and other parameters.

3. The power supply uses a hierarchical protection leakage protection do, should meet on selective lower switching operation. Generally a leakage protection is not less than the nominal leakage current leakage protection under a nominal leakage current, both to protect sensitive personal and equipment safety, but also to avoid grade trip to narrow the scope of an accident inspection.

The hand-held power tools (except for Class III), mobile life with appliances (except outside the class III), other portable electrical equipment, as well as a greater risk of electric shock device, you must install leakage protection.

5. construction sites, temporary line of electrical equipment should be installed leakage protection. This is the "construction site temporary electrical safety technical specifications" in (JGJ46-88) specifically requested.

6. agencies, schools, businesses, residential buildings within the outlet circuit, hotels, restaurants and guest houses, rooms outlet circuit, you must also install leakage protection.

7. power lines and equipment installed in the water and damp, workplace temperature, metal and other conductive possession coefficient greater good places, such as machining, metallurgy, textile, electronics, food processing and other industries, as well as boiler room, pump room, dining room, bathroom, hospitals and other places, must be used to protect leakage protection.

8. fixed-line electrical equipment and normal production workplace, should be used with leakage protector power distribution box. Small temporary use electrical equipment should be used in leakage protection plug (seat) or with leakage protection socket box.