Q1: What is a insulation tester?
A1: Insulation tester, also known as megohmmeter or meggers, are widely used to measure cables for generators, motors, power transformers, wiring, appliances and other electrical installations such as control, signal, communication and power ) insulation resistance. They are often used in routine maintenance procedures to indicate changes in the insulation resistance of a motor over months or years. Large changes in insulation resistance may indicate potential failures. Therefore, regular calibration of the megohmmeter is required to ensure that the meter itself has not changed over time.
Q2: What is insulation resistance?
A2: Insulation resistance is the DC resistance of the insulation under the specified conditions, that is, the DC voltage is applied to the dielectric, after a certain period of polarization, the resistance corresponding to the leakage current flowing through the dielectric is called insulation resistance. It is the most basic insulation index of electrical equipment and electrical circuit.
Q3: How to measure insulation resistance?
A3: 1. Connect all the lines according to the method measured by the insulation resistance tester. The connection between the measuring lead and the pipe is more suitable for the use of magnetic joints or clips, and the connection point must be free of rust.
2. The measuring instrument should be a 500V/500MΩ (the error here cannot be greater than 10%) insulation tester. Turn the handle of the megohmmeter to reach the specified speed for 10 seconds. The resistance value indicated by the megohmmeter stably is the insulation resistance value of the insulating joint (flange), which is required to be greater than 10 megohms.
Insulation resistance tester working principle
The insulation resistance tester is the intelligent dual-display insulation resistance tester (two gears), which adopts the embedded industrial single-chip real-time operating system, and the digital analog pointer and the digital segment code display are perfectly combined. This series of meters has a variety of voltage output levels, large capacity, strong anti-interference, AC and DC dual-use, simple operation, various measurement results with anti-power failure function and so on. It is an ideal test instrument for measuring insulation resistance of large-capacity transformers, transformers, generators, high-voltage motors, power capacitors, power cables, arresters, etc.
The insulation resistance tester mainly uses Ohm's law to measure the resistance by exciting the device or network under test with a voltage, and then measuring the current generated by the excitation. For example, these electrical testers apply much higher voltages when making resistance measurements than the ohmmeter function equipped on a digital multimeter (DMM). Megohmmeters typically use voltages ranging from 50V to as high as 5 kV; while typical DMMs typically operate at less than 10 V. For insulation testing, the resistance value that needs to be measured has a wide range, the upper limit can reach 10TΩ, and the required voltage is higher.