The digital megohmmeter has large capacity, strong anti-interference, synchronous display of hands and digital, AC and DC, simple operation, automatic calculation of various insulation indexes (absorption ratio, polarization index), and various measurement results with anti-power-down function. Features. The working principle is that the DC high voltage generated by the DC/DC conversion of the battery in the machine is passed from the E pole to the L pole through the tested product, thereby generating a current from the E to the L pole, and is completed by the I/V conversion through the divider. The calculation directly displays the measured insulation resistance value by the LCD. The megohmmeter (insulation resistance meter) commonly used in electrician operation has a hand-operated megohmmeter and a digital megohmmeter. The hand-operated megohmmeter consists of a dial, a pointer, and a terminal (E-ground terminal, L-phase line). Terminal block), nameplate, manual rocker, instructions for use, red test clips, and black test clips. The digital megger is composed of a digital display, a test line connection jack, a backlight switch, a time setting button, a measuring knob, and a range adjustment knob. Digital megohm display, display symbols and instructions Digital megger use practice The method for detecting the insulation resistance of a transformer using a digital megger is as follows: 1. View the transformer to be tested When using a digital megohmmeter to detect the insulation resistance of a transformer, it is necessary to separately detect the insulation resistance between the windings of the transformer and the insulation resistance between the cores. 2. Adjust the range of the digital megger and connect the test leads Adjust the range of the digital megohm meter to "500V", and the display will also display the range of 500V; then insert the red test lead into the "LINE" hole of the line, and then insert the black test lead into the ground "EARTH" In the hole. 3. Test the insulation resistance of the transformer primary winding and the core Place the digital megger red test pen on any core of the primary winding of the transformer. The black test pen is placed on the metal casing of the transformer. Press the test button of the digital megohmmeter. At this time, the digital megohmmeter The display panel shows an insulation resistance of "500MΩ". 4. Test the insulation resistance between the secondary winding of the transformer and the core Place the digital megger red test pen on any of the secondary windings of the transformer. The black test lead is placed on the metal casing of the transformer, and then the digital megohm test button is pressed. At this time, the digital megaphone The display panel of the Euro meter shows the insulation resistance as "500MΩ". 5. Test the insulation resistance between the primary winding and the secondary winding of the transformer Place the digital meter's red test pen on any of the secondary windings of the transformer. The black test lead is placed on any of the primary windings of the transformer, and then press the test button of the digital megger. At this time, the display panel of the digital megohmmeter shows that the insulation resistance is "500 MΩ". When using a megohmmeter to measure the insulation resistance of the cable, when the megohmmeter is applied with a voltage of 1000V, the insulation resistance of the cable should reach “1MΩ†or more. If the applied voltage is 10kV, the cable The insulation resistance should reach "10MΩ" or more, which indicates that the cable has good insulation performance. If the insulation performance of the cable does not meet the above requirements, it may cause a short-circuit fault during operation with the connected electrical equipment. There are many models of megohmmeters, and the more common ones are BY2671, WD-3121 and WD-3125. The voltage levels range from 500/1000/2500/5000/10000V and need to be selected according to specific parameters. Below we detail several common electrician digital megohm models: Commonly available are ME20Z series pointer type insulation resistance tester, UT513 insulation resistance tester, MEV-5000 insulation resistance tester ME20Z series pointer type insulation resistance tester function: ME20Z series pointer type insulation resistance tester adopts ultra-thin wire head, multiple voltage level output, large capacity, strong anti-interference, AC and DC, simple operation and time prompt function. ME20Z series pointer type insulation resistance tester product features: 1. ME20Z series pointer type insulation resistance tester insulation test for ME2533 at 500V up to 20GΩ, 1000V up to 40GΩ, 2500V up to 100GΩ; for ME2550 at 2500V up to 100GΩ, at 5000V maximum 200GΩ is measured; for the ME2565, the maximum measurable 200GΩ at 5000V and 400GΩ at 10000V can be measured. 2. The rated output voltage can be kept as low as 4MΩ/8MΩ/20MΩ for the ME2533 load resistor; 20MΩ/40MΩ for the ME2550Z type; 40MΩ/80MΩ for the ME2565 type, enabling the meter to accurately measure the lower insulation resistance. 3, automatic conversion of the high and low range of double-scale indication, color scale is easy to read, and there are LEDs to display the corresponding color. 4. The whole machine adopts the portable design of ABS plastic casing, which has strong anti-interference ability, compact structure and beautiful appearance. 5. ME20Z series pointer type insulation resistance tester adopts ultra-thin type wire head and has strong seismic resistance. 6, each type C is AC and DC, built-in rechargeable battery and intelligent charging module, the whole machine output power. ME20Z series pointer type insulation resistance tester product parameters UT513 insulation resistance tester product introduction UT513 digital insulation resistance tester, also known as megger meter; the basic measurement range of the instrument is 0.5MΩ~1000GΩ, the test voltage is 500V/1000V/2500V/5000V four gears, the whole circuit design adopts microcomputer technology design as the core, to large scale The combination of integrated circuit and digital circuit is equipped with powerful measurement and data processing software to complete the measurement of insulation resistance, voltage and other parameters, with stable performance and simple operation. The products are suitable for electric power, telecommunications, post and telecommunications and general industrial and mining enterprises and railway systems. UT513 Insulation Resistance Tester Product Features 1, digital megohmmeter has automatic release voltage function 2, USB interface data transmission 3, the backlight function is easy to work in dark light 4, the bar chart shows the measurement results 5, high pressure prompt and red warning light 6, automatic shutdown function: 15 minutes after the end of the measurement will automatically shut down if not operating, automatically turn off the power and press the ON / OFF button for 1 second before booting 7, 18 sets of data storage functions 8, set the test time TIME function: automatically perform measurement within 15 minutes of the specified time 9, COMP measurement (comparative function measurement) 10. PI measurement (polarization index measurement) PI measurement can automatically measure the resistance ratio according to the setting at any two time points. 11, the error limit: ± (a% reading + word count), the guarantee period of one year 12, the ambient temperature: 23 ± 5 ° C UT513 insulation resistance tester technical parameters MEV-5000 Insulation Resistance Tester Product Introduction: This instrument is a new type of intelligent instrument, which is the best choice for testers. The short-circuit current of MEV5000 is more than 3mA, which overcomes the shortcomings of short-circuit current of ordinary type megohmmeter, inaccurate test and easy to be interfered. The MEV5000 takes a timely voltage and current sampling to perform the division operation, so even if the voltage changes during the test, the resistance value calculated by the ohm theorem is accurate. The meter adopts advanced single-chip control flow, man-machine interface dialogue, easy to carry and simple operation; battery is included, AC and DC are used, and undervoltage protection and battery overcharge protection are provided. The instrument can automatically display the current time, save 8 sets of historical test data and time, which provides great convenience for the testers. MEV-5000 insulation resistance tester product parameters: Digital megohmmeters are essential instruments for power, post and telecommunications, communications, electromechanical installation and maintenance, and industrial enterprises that use electricity as an industrial power or energy source. The digital megger is suitable for measuring the resistance of various insulating materials and the insulation resistance of transformers, motors, cables and electrical equipment. Megohmmeters, also commonly referred to as insulation resistance shakers, digital shakers, electric shakers, etc., are meters that measure high resistance and are often used to measure the insulation resistance of electrical equipment or power lines. The megohmmeter is easy to operate, simple in reading and small in size. It is a portable instrument. The dial of the megohmmeter is in megaohms (MΩ). The megohmmeter is mainly based on its voltage and measurement range to select the corresponding instrument. High-voltage electrical equipment needs to use a high-ohmmeter megohmmeter, and low-voltage electrical equipment needs to use a low-voltage megohmmeter. The general selection principle is: 500-1000 volt megohmmeter for electrical equipment below 500 volts; megger gauge for 2500 volts or more for porcelain bottles, busbars, and knife gates. The selection principle of the megohmmeter measurement range is: to adapt the measurement range to the value of the measured insulation resistance, effectively avoiding large errors in reading. For example, some megohmmeter readings do not start from zero, but start at 1 megohm or 2 megohm. Megohmmeters are not suitable for measuring the insulation resistance of low voltage electrical equipment in humid environments. Because the insulation resistance of this device may be less than 1 megohm, the meter can not get the reading, it is easy to mistake the insulation resistance is zero, which is easy to cause the result wrong. In the selection of the resistance range, it is necessary to pay attention to the two small black points on the dial scale of the shake table, and the area between the small black points is the accurate measurement area. Therefore, when selecting the meter, the insulation resistance value of the device under test should be within the accurate measurement area. When the megohmmeter is working, it will generate high voltage itself, and the measuring object is electrical equipment, so it must be used correctly, otherwise it will cause equipment accidents and even personal safety accidents. The use of megohmmeters requires the following preparations: (1) Before the measurement, the power of the device under test must be cut off, and the ground should be short-circuited. The device must not be energized for measurement to ensure the safety of the person and equipment. (2) For equipment 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), Megohm lead wire application of multi-strand soft wire, and should have good insulation; (6) Double-circuit overhead lines and busbars that cannot be completely de-energized are prohibited from being measured when the induced voltage of the circuit under test exceeds 12 volts, or when overhead lines during lightning storms and electrical equipment connected to overhead lines are used; (7) The megohmmeter should be placed in a stable and stable place and away from large external current conductors and external magnetic fields. Pay attention to the following points when measuring: 1, measuring the insulation resistance of electrical equipment, must first cut off the power supply, encountered equipment with capacitive properties, such as cables, the line must be first discharged. 2, the megohmmeter must be laid flat when used. 3, the megohmmeter should be rotated a few times before use to see if the pointer is at the maximum position, then short the two terminals "L" and "E", slowly rotate the megohmmeter handle, view Whether the pointer is at "zero". 4, Megohm lead must be well insulated, do not twist the two wires together. 5, the meter is measured, the reading after one minute of rotation shall prevail. 6, in the measurement, the megohmmeter should be rotated to 120 rpm. 7, the range of megohmmeter often reaches several gigaohms, and the minimum scale is about 1 megohm, so it is not suitable for measuring resistance below 100 kohm. The megohmmeter has the following considerations in its use: (1) It is forbidden to measure the insulation resistance during lightning or near high-voltage equipment, and only when the equipment is not charged or inductive. (2) During the shaking test, no one is allowed to work on the device under test. (3) The shaking table wires cannot be twisted together and should be separated. (4) It is strictly forbidden to touch the hand before the shake table has not stopped rotating or before the device under test is not discharged. Do not touch the metal part of the lead when disconnecting the wire. (5) At the end of the measurement, the large capacitance device is subjected to discharge treatment. (6) Regularly check the accuracy of the megohmmeter. Note the use of a megohmmeter to measure electrical insulation: The 1 megohm meter must be kept flat when in use. The speed of 2 megohms is 120 rpm. 3 Self-examination: A, open circuit test; the number of megaohms reaches 120r/min, and the pointer should be at “âˆâ€. B. Short circuit, slowly rotate the megohmmeter, the pointer should be at “0â€. 4 The insulation resistance between the windings, phase and phase, phase and outer casing of the motor should be ≥0.5MΩ. Mobile power tool ≥ 2MΩ 5 When measuring line insulation: phase and phase ≥0.38MΩ, phase and zero ≥ 0.22MΩ. 6 medium and small motors are generally selected 500-1000 type. 7 If the phase resistance is zero, it indicates that the phase is shorted. 8 If the phase resistance is 0.1 or 0.2 MΩ, the phase insulation resistance performance has been reduced. 9 The insulation resistance of electrical equipment is as large as possible, as far as possible. 10 If the insulation resistance of the motor or line is degraded, and a short circuit occurs, the megohmmeter needs to be repaired and cannot be used normally. 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