Insulation performance test equipment preferred [Shanghai Haiyue] high-voltage insulation tester

Chinese name: high voltage insulation resistance tester

Foreign name: High Voltage Insulation Resistance Tester

Common name: Megger

Function: measuring various transformers, motors, cables

Suitable for insulation testing in the maintenance, repair, testing and verification of various electrical equipment. The insulation resistance index line is even and clear, which is convenient for accurate reading. Easy to operate and easy to carry. Low power consumption, powered by 8 x 1.5V (AA, R6) battery, long time. Has a battery capacity check function. There are single-voltage and dual-voltage models, and the rated voltage and range are reasonably configured into various specifications. It adopts advanced digital processing technology, with large capacity and strong anti-interference ability. It can meet the requirements of high-voltage, high-resistance and large-capacity load test, and the indication value is accurate, stable and reliable. It has anti-vibration, moisture-proof and dust-proof structure to adapt to the harsh working environment. The protection function is perfect, can withstand short circuit and residual voltage impact of the measured capacitor.

Test voltage: 0V~10000V, various specifications are available, and can be customized according to requirements

Shanghai Haiyue Electronic Technology Co., Ltd. was established in 2006. Since its establishment, the company has been focusing on the R&D, production and sales of safety and electromagnetic compatibility test equipment. The company's main personnel have nearly 20 years of experience and rich practical experience. It has successfully provided a number of large-scale certification laboratories with the planning of test equipment and the supply of corresponding test equipment. The company produces hundreds of various types of safety equipment and test instruments, and undertakes non-standard custom test equipment.

The company has always adhered to the rigorous attitude, adhering to the "integrity as the cornerstone, providing professional technical services, perfect solutions, high-quality testing equipment" concept, constantly improve after-sales service, improve product quality, and strive to become the industry leader By.

Our company's high-voltage insulation resistance tester, English name: High Voltage Insulation Resistance Tester. The instrument is suitable for measuring the insulation resistance of various transformers, motors, cables, switches, electrical equipment and insulating materials.

High-voltage insulation resistance tester is commonly known as megohmmeter, or shaker, high-impedance meter, insulation resistance tester, etc. Insulation resistance meter is a kind of measuring instrument which is widely used in electric power websites and electrical equipment insulation resistance. It is of great significance to ensure product quality and personal and equipment safety during operation. The insulation performance of electrical products is an important indicator to evaluate its insulation quality. First, it is reflected by the insulation resistance.

1, high-voltage insulation resistance tester is mainly composed of three parts.

The first is a DC high voltage generator to generate a constant current high voltage.

The second is the measurement loop.

The third is the display.

(1) DC high voltage generator

Measuring the insulation resistance must apply a high voltage at the measuring end. This high voltage value is specified in the national standard of the insulation resistance meter as 50V, 100V, 250V, 500V, 1000V, 2500V, 5000V...

There are generally three methods for generating DC high voltage. The first type of hand-cranked generator. At present, about 80% of the megohmmeter produced in China is using this method (the source of the name of the shaker). The second is to boost the DC voltage through the mains transformer. The method used in general utility meters. The third is a method using a transistor oscillating or dedicated pulse width modulation circuit to generate a DC high voltage, a general battery type and a commercial type insulation resistance meter.

(2) Measurement circuit

In the shake table (Megohmmeter) mentioned above, the combination of the measurement loop and the display section is one. It has a flow ratio meter head. The head has two coils with an angle of 60° (left and right). One coil is at both ends of the voltage and the other coil is in the measuring loop. middle. The deflection angle of the head pointer is determined by the current ratio in the two coils. Different deflection angles represent different resistance values. The smaller the measured resistance value, the larger the coil current in the measurement loop, and the greater the angle of deflection of the pointer. . Another method is to use a linear ammeter as the measurement and display. The flow ratio used in the front of the meter is non-uniform due to the magnetic field in the coil. When the pointer is at infinity, the current coil is just where the magnetic flux density is the strongest. Therefore, although the measured resistance is large, the current coil current flows. Rarely, the deflection angle of the coil will be large at this time. When the measured resistance is small or 0, the current flowing through the current coil is large, and the coil has been deflected to a place where the magnetic flux density is small, and the angle of deflection caused thereby is not large. This achieves a nonlinear correction. The resistance display of a typical megohmmeter header needs to span several orders of magnitude. However, when the linear current meter is directly connected to the measuring circuit, the scales at high resistance are all squeezed together and cannot be resolved. In order to achieve nonlinear correction, nonlinear components must be added to the measuring circuit. Thereby, a shunting effect is achieved at a small resistance value. At high resistance, no shunting occurs, resulting in resistance values ​​that are orders of magnitude. With the development of electronic technology and computer technology, digital meters have gradually replaced pointer meters.

The digital measurement technology of insulation resistance has also been developed. Among them, the voltage ratio meter circuit is one of the better measurement circuits. The voltage ratio meter circuit is composed of a voltage bridge and a measurement bridge. The signals output by the two bridges are respectively converted into digital value display by A/D conversion and then by a single chip.

Tester

Determination of the insulation resistance of the product refers to the insulation resistance between the live part and the exposed non-charged metal part (outer case). According to different products, apply high-current high-voltage, such as 100V, 250V, 500V, 1000V, etc., to specify a minimum insulation. resistance. Some standards stipulate that the insulation resistance should not be less than 1MΩ per kV voltage. At present, in the standard of household appliances, usually only the thermal insulation resistance is specified, and the insulation resistance value under normal conditions is not specified. The insulation resistance value under normal conditions is determined by the enterprise standard. If the normal insulation resistance value is low, there may be some hidden danger or damage in the insulation structure. If the insulation resistance of the motor winding to the outer casing is low, it may be caused by damage to the insulation of the winding of the winding during the weld. When using an appliance, the circuit generates an overvoltage due to sudden power-on or power-off or other reasons, causing breakdown at the insulation damage, resulting in safety or threat to the person.

1, insulation resistance meter (Megohmmeter) - an electrical measuring instrument for measuring the direct acting analog indication of the insulation resistance, the unit of which is expressed in MΩ.

2. Measuring terminal - Insulation resistance meter is used to connect the terminal to be measured. The measuring end button of the insulation resistance meter shall be marked with the line terminal button L, the ground terminal button E, and the symbol of the shielding terminal button G, respectively.

3, the terminal voltage - the voltage between the insulation resistance meter line terminal and the ground terminal.

4. Rated voltage - Insulation resistance meter measures the nominal value of the output voltage when the terminal is in an open state.

5. Open circuit voltage - Insulation resistance meter measures the measured value of the output voltage measured when the terminal is in an open state.

6, the median voltage - insulation resistance meter measurement terminal L, E connected to the value of the output voltage measured by the median resistance.

Electrical insulation is not just a plastic polymer material wrapped around a wire. It is a complete system consisting of cable insulation, bushing insulators, conduit space, motors and general equipment. Mechanical stress, contamination, and temperature changes can cause these components to deteriorate over time, causing current leakage. Current leakage can cause the following problems:

1. When heat is passed through the insulation layer, heat is generated, which will deteriorate the insulation layer until the final insulation fails, and a fire hazard may be formed.

2. The leakage current must be returned to the source, which will flow back to the source through any available conductor, conduit, pipe, water or earth. This unfavorable current can create dangerous voltages.

3. Leakage current is inefficient. The current leaking through the insulating layer does not drive the motor, illuminate or heat, but still consumes.

4. Leakage current can cause the overcurrent protection device to trip, causing the motor and transformer to overheat. The result is poor electrical insulation that causes equipment failure and production line downtime. No factory now can withstand unplanned downtime. “Customers need to quickly diagnose faults. No one wants to lose production time, and many customers are eager to know if they need to repair equipment or simply replace it.”

An electrical system is like a piping system. The voltage is like the liquid pressure. The current is like the flow rate of the liquid, and the electrical insulation is like the wall. Insulation prevents electrons from leaking from the conductor - the magnitude of its effect is expressed by the insulation resistance. An effective insulation resistance system has a high resistance value, typically greater than a few megaohms (MΏ). Poor insulation systems have lower insulation resistance.

In order to find leaks in the piping system, you need to pressurize it. Since leakage is most easily detected at the highest water pressure, you cannot turn off tap water to check for leaks. However, you will limit the amount of tap water available so that you don't have to spray too much water around when you find a large hole. The ideal test is to provide a limited amount of water at high (but not particularly high) pressure. This is exactly what the electrical insulation tester has to do.

The insulation tester (Megohmmeter) applies a DC voltage to the insulation system and measures the resulting current. This makes it possible to calculate and display the value of the insulation resistance (how much insulation insulates the current in the wire, or the extent to which the current is prevented from leaking).

Portable insulation testers (Megohmmeters) typically output test voltages of 50 V, 100 V, 250 V, 500 V or 1000 V. As in the piping system, the aim is to provide a pressure (voltage) that is not particularly high. We hope to find existing leaks, but we don't want to overstress the system to create new leaks. Lower voltages are used for low voltage systems such as telephone, network or control lines; higher pressures are used to test power system insulation.

The role of testing

By testing the insulation resistance (transformers, switchgear, wires, motors) of the various components in the system, the technician can isolate and repair the failed component. The technician uses the test to verify the high insulation resistance between the wire and the ground or adjacent wires. Two common examples are testing the insulation between the motor windings and the motor base, as well as checking the resistance between the phase conductor and the ground wire/cage. Before powering up the system, it is verified by insulation testing that it is robust and can improve the performance of the system; insulation testing can identify manufacturing process problems and equipment defects that are generally not discovered before the equipment fails. In the European Union, this test is mandatory, even for the smallest civil systems.

1. Rotate the band switch at any voltage level and the power is turned on.

2. In the state of selecting the test number, press the setup button (12) to enter the query test result status.

3. Press the up and down keys (12) to increase and decrease the number of the test results. (The corresponding number is anti-black).

4. After selecting the number, press the test button (10) to enter the test result of the number. Press the up and down button (12) to query the number test result (current resistance, 15 seconds resistance, 60 seconds resistance, 10 minutes resistance, absorption ratio, polarization index).

5. After the query is completed, press the setup button (12) to return to the ready test state.

6. If you need to query again, press the setting button (12) again.

Dangerous matters

Do not measure circuits with AC/DC voltages above 600V.

Do not test in a flammable location. Activation may cause an explosion.

Do not operate the instrument if the surface of the instrument is wet or if the hands are wet.

When measuring, do not touch the conductive parts of the test pen.

Do not press the TEST button when the test leads are shorted to the instrument.

Do not open the battery cover while measuring.

When measuring insulation, do not touch the line to be tested.

Precautions

Before measuring the resistance, the circuit under test must be completely discharged and completely isolated from the power supply circuit.

If the test pen or power adapter is damaged and needs to be replaced, you must replace the test pen and power adapter of the same model and the same electrical specifications.

Do not use the instrument when the battery indicator indicates that the power is exhausted. If you do not use the instrument for a long time, remove the battery and store it.

Do not store or use the instrument in high temperature, high humidity, flammable, explosive or strong electromagnetic fields.

Use a damp cloth or detergent to clean the case. Do not use abrasives or solvents.

When the instrument is wet, please dry it and store it.

The company also sells a number of well-known safety equipment manufacturers at home and abroad, including: US COMPWEST, Italy ATS, US ED&D, Taiwan Whale, Japan SOKEN, Japan KIKUSUI, Japan YOGOGAWA, Taiwan Epps, Japan SOKEN, Japan ESPEC and many more.

The company provides complete EMI and EMS equipment in the field of electromagnetic compatibility. The agent supply includes European EM-TEST, Italian AFJ, German FRANKONIA, Swiss EMC-PARTNER, Japan MORITA and many other manufacturers. At the same time, the company is also the sales outlet of Beijing Kehuan in East China. .

It is our goal to improve the customer's test equipment, improve the customer's test level and increase customer satisfaction. We believe that Haiyue Club is your best partner with high quality testing equipment and professional technical services!