With the improvement of living conditions of residents, a large number of household appliances enter the bathroom, such as Yuba, electric water heaters, multi-function toilets, lamps, etc., there may be leakage when using electricity, the use of household appliances to life Convenient brings with certain safety hazards, but some people think that measures have been taken in the bathroom: electric water heaters, Yuba and other electrical equipment shells have been grounded (connected to PE line), the entire building has been carried out Equipotential bonding, leakage protection devices have been installed in the user's power distribution box, and are not used as repeated local equipotential bonding. In fact, such statements are wrong.
The leakage protection device is a kind of protection for leakage of equipment. The operating current is 10-30 mA and the operation time is 0.1 s. The leakage protector in the low-voltage distribution system is one of the effective measures to prevent personal electric shock accidents. It is also to prevent electrical leakage caused by electric leakage. Technical measures for fire and electrical equipment damage accidents. However, the installation of the leakage protector does not mean absolute safety. It should be based on prevention during operation, and other technical measures to prevent electric shock and electrical equipment damage should be taken at the same time. The bathroom is listed as a special place for electric shock hazard by international electrical standards. Electric shock accidents in our bathroom are also frequent. This is because people are soaked in the body during bathing, the body's impedance is greatly reduced, and the voltage of 10~20V introduced into the bathroom along the metal pipe or other equipment is enough to cause ventricular fibrillation and death, so the bathroom with leakage protection device is There is no safety requirement, and now the better precaution is to make a local equipotential bonding in the bathroom. In this way, no matter where the abnormal voltage is introduced, due to the action of the equipotential bonding, the potentials of all the conductive parts in the place are simultaneously raised to the same potential level, and no potential difference is generated, so that the electric shock can be greatly avoided. hurt. The principle is similar to the bird standing on the high-voltage line. It is the same reason that there is no potential difference between the two feet and will not be shocked. Therefore, the electric shock accident will naturally not occur, and the personal safety and the safety hazard can be effectively ensured. Therefore, it is necessary to increase the local equipotential in the bathroom.
What is a local equipotential bonding should first find out what is the equipotential bonding. The definition is given in the new Residential Design Code standard implemented in June 1999. The equipotential bonding is to electrically connect all the large metal components inside the building and the building itself with busbars or wires to make the whole building. The normal non-charged conductor of the object is in electrical communication. Usually equipotential bonding is divided into three levels, namely total equipotential bonding, local equipotential bonding and auxiliary equipotential bonding. Local equipotential bonding is generally caused by electric shock accidents in particularly dangerous places such as bathrooms, swimming pools, hospital operating rooms, etc. It is more dangerous and requires a lower contact voltage. There are multiple auxiliary equipotential bonding in these local ranges to meet the requirements. This connection is called local equipotential bonding. Simply put, a local equipotential bonding can be seen as a total equipotential bonding in a localized range. According to theoretical analysis, the smaller the equipotential bonding range is, the safer the electrical is. If the equipotential bonding is performed within the range of the residential building, the effect is of course much better than the grounding.
At present, lightning protection design of building buildings, electrical building designers in the drawings for the building grounding mostly use the basic steel bars as the grounding body, the roof using pre-discharge lightning rods or lightning protection grid as the lightning body, the construction of some of the main steel bars as the down conductor Through the grounding body and the lightning body, the local equipotential bonding of the bathroom is often too simple to explain, even just saying "requires the installation of local equipotential devices", and the current bathroom water supply and drainage materials use plastic pipes, even using floor heating, as Construction units often ignore the importance of local equipotentials in the bathroom, and even believe that local equipotentials may not be provided.
In view of the above phenomenon, the following describes the local equipotential bonding in the bathroom in combination with the actual situation of the equipment used in the existing bathroom. The introduction of local equipotential grounding should use 40*4 or 25*4 galvanized flat steel, and lead the welding to the local equipotential box of the bathroom from the lightning protection down conductor of the nearby building (multiple from the diagonal main rib of the structural column), and the structure When the main ribs of the column are welded, the doubling requirement is double-sided welding, the length is more than 2 times the width of the flat steel, and the local equipotential box is provided with a copper row, and the connection between the copper row and the flat steel in the box is screwed. In the bathroom, Yuba, water heater socket ground wire, radiator, heating metal pipe, water supply and drainage and other metal pipes need to reserve 86 boxes in advance, and use PVC20 electric flame retardant pipe (the inside of the pipe is not less than BRV4mm2) to reserve 86 boxes and The local equipotential box is penetrated, and the ends of the BRV line are hot tinned and pressed to connect the nose. Ground steel mesh (when the wall is a concrete wall, the steel mesh in the wall should also be connected) can be connected with the copper bar in the equipotential box by 40*4 or 25*4 galvanized flat steel, the ground reinforcing mesh and the reinforcing mesh in the wall Before the concrete is poured, the welding is carried out, and the longitudinal and transverse reinforcing bars are penetrated, and the overlapping multiple is not less than 5 times the diameter of the steel bar.
After the connection of the local equipotential box is completed, the continuity test shall be carried out. The test instrument may use a megohmmeter. If the resistance between the equipotential bonding terminal plate and the end of the metal pipe is not more than 3 ohms, it can be considered as effective. If it is found that there is a pipeline that does not meet the resistance requirements, you can make a jumper connection.
Since the implementation of equipotential bonding in China is still in its infancy, there are still considerable gaps in other developed countries. Terminal boards and accessories for equipotential bonding are already mature products in developed countries, but there are still no fixed products, bathtubs, etc. in China. There is no terminal for the equipment. Therefore, it is necessary to make the terminal board, hoop, etc. at the construction site, which is laborious and time-consuming. The long-term use of the grounding resistance is unstable, easy to be removed and less beautiful. The paper was published to ensure safety. . The paper was published to ensure safety. . In the actual construction, most residential toilets only reserve the upper and lower water pipes, radiators and other potential interfaces and equipotential bonding terminal plates. Bathtubs, water heaters, Yuba and other equipment are installed at the later stage of the household, while households or decoration units often ignore such Safety requirements, only pay attention to the aesthetic effect of decoration, the decoration unit has no electrical installation professionals, to do local equipotential in the bathroom and how to do it without knowing or feeling it is not necessary, which results in the bathroom part after the completion of the renovation of the household, etc. The potential does not reach the expected effect, and it becomes a decoration. For this purpose, there must be a process handover procedure between the developer and the decoration unit. This procedure can be used to make this unfinished local equipotential approach and importance through the house instruction manual. It is clear that the residents complete the remaining repetitive grounding devices during the renovation to meet the specification requirements. The paper was published to ensure safety. . When the property company needs to check the structure of the house after the decoration of the decoration unit is completed, it is necessary to unify the equipotential connection of the bathroom into the acceptance content. For the unqualified one, it is necessary to give a reminder to perfect or force recovery to ensure the safety of electricity consumption.
Displacement sensor, also known as linear sensor, is a linear device belonging to metal induction. The function of the sensor is to convert various measured physical quantities into electricity. In the production process, the measurement of displacement is generally divided into measuring the physical size and mechanical displacement. According to the different forms of the measured variable, the displacement sensor can be divided into two types: analog and digital. The analog type can be divided into two types: physical property type and structural type. Commonly used displacement sensors are mostly analog structures, including potentiometer-type displacement sensors, inductive displacement sensors, self-aligning machines, capacitive displacement sensors, eddy current displacement sensors, Hall-type displacement sensors, etc. An important advantage of the digital displacement sensor is that it is convenient to send the signal directly into the computer system. This kind of sensor is developing rapidly, and its application is increasingly widespread.
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