![<?echo $_SERVER['SERVER_NAME'];?>](/template/twentyseventeen/skin/images/header.jpg)
Modern life is changing with each passing day, and people can't live without electricity for a moment. There are electrical safety issues in the process of electricity use, in electrical equipment, such as motors, cables, household appliances, and so on. One of their normal operations is the degree of insulation of the insulating material, ie the value of the insulation resistance. When heated and damp, the insulation ages. Its insulation resistance is reduced. This causes electrical equipment leakage or short circuit accidents. In order to avoid accidents, it is required to measure the insulation resistance of various electrical equipment frequently. Determine if the insulation level meets the needs of the equipment. Common resistance measurements are usually measured at low voltage and at high voltage. The insulation resistance is higher due to the general value (generally megaohms). Measurements at low voltages do not reflect true insulation resistance values ​​operating at high voltages. The megohmmeter is also called an insulation resistance meter. It is the most commonly used meter for measuring insulation resistance. It has a high-voltage power supply when measuring the insulation resistance, which is the difference between it and the resistance meter. The megohmmeter is convenient and reliable for measuring insulation resistance. However, if used improperly, it will bring unnecessary errors to the measurement, we must use the megohm insulation resistance to measure correctly.
When the megohmmeter is working, it generates high voltage itself, and the measuring object is electrical equipment, so it must be used correctly, otherwise it will cause personal or equipment accidents. Before using, you must first make the following preparations:
(1) Before the measurement, the power of the device under test must be cut off and short-circuited to the ground. The device must not be energized for measurement to ensure the safety of the person and equipment.
(2) For devices that may induce high voltage, the possibility must be eliminated before measurement can be made.
(3) The surface of the object to be tested should be cleaned to reduce the contact resistance and ensure the correctness of the measurement results.
(4) Before the measurement, check whether the megohmmeter is in normal working condition, mainly check the two points of “0†and “∞â€. That is, the handle is shaken to make the motor reach the rated speed. The megger should be in the “0†position when it is short-circuited and “∞†when it is open.
(5) The megger should be placed in a stable and strong place and away from large external current conductors and external magnetic fields.
After the above preparations are made, the measurement can be carried out. When measuring, pay attention to the correct wiring of the megohmmeter, otherwise it will cause unnecessary errors or even errors.
There are three terminals of megohmmeter: one is “Lâ€, that is, the line end, one “E†is the ground end, and another “G†is the shield end (also called the protection ring). Generally, the insulation resistances to be tested are connected. Between the "L" and "E" ends, but when the surface of the tested insulator leaks severely, the shield ring of the test object or the portion that does not need to be measured must be connected to the "G" end. Thus, the leakage current flows directly back to the negative end of the generator via the shield end "G" to form a loop, rather than flowing through the megohmmeter measuring mechanism (moving coil). This fundamentally eliminates the influence of surface leakage current. In particular, it should be noted that when measuring the insulation resistance between the cable core and the outer surface, the shield terminal "G" must be connected because the air humidity is high or the cable is insulated. When the surface is not clean, the leakage current on the surface will be very large. In order to prevent the measured object from being affected by leakage, its internal insulation measurement is generally added to the outer surface of the cable with a metal shielding ring, and the megger of the megohmmeter. "End connected.
When using the megohmmeter to measure the insulation resistance of electrical equipment, be sure to note that the "L" and "E" ends cannot be reversed. The correct connection method is: "L" line end button is connected to the conductor of the device under test, "E" The grounding device is grounded, and the “G†shield terminates the insulated part of the device under test. If the "L" and "E" are reversed, the leakage current flowing through the insulator and the surface is collected to the ground through the outer casing, and the ground flows through the "L" into the measuring coil, so that the "G" loses the shielding effect and gives the measuring tape. There is a big error. In addition, because the inner lead of the "E" end is insulated from the outer casing by a degree of insulation lower than the "L" end and the outer casing, when the megohmmeter is placed on the ground, when the correct wiring is used, the "E" end is opposite to the outer casing of the instrument. The insulation resistance of the shell to the ground is equivalent to a short circuit and does not cause an error. When the "L" and the "E" are reversed, the insulation resistance of the "E" to the ground is in parallel with the measured insulation resistance, and the measurement result is biased. Small, bringing a big error to the measurement.
Still using a foot pump to inflate the articles? Try the Electric Air Pump to free your foot, With Rechargeable Air Mattress Pump, you can relax and enjoy the outdoor journey totally. It is not only a Rechargeable Air Bed Pump suitable for air bed, air mattress, but also a multiple use Rechargeable Air Pump For Inflatables for pool floatings, balloons. Very essential product for every person who go out for camping & water sports. a Rechargeable Air Bed Pump will be a good helper
Our electric air pump is battery operated, with built in batteries and strong air flow to inflate the airticles easy & quickly. Each product are certified wtih CE, Rohs, FCC, PSE, KC eat. Welcome to contact us for product information!
Rechargeable Air Mattress Pump,Rechargeable Air Pump For Inflatables,Trespass Rechargeable Air Pump,Rechargeable Air Bed Pump
SHENZHEN SMARTNEWO TECHNOLOGY CO,. LTD , https://www.newopump.com