The choice of megohmmeter: how big is the megohmmeter to buy
When selecting the size of the megohmmeter, it needs to be determined according to the withstand voltage level of the electrical equipment.
If you are an electrician engaged in low-voltage operation, you generally choose a 250V-500V megohmmeter, and if you are an electrician engaged in high-voltage operation, you can choose a 1000V-5000V megohmmeter.
When measuring 250V electrical equipment, you can use a 1000V or 5000V megohmmeter to measure its insulation resistance value, which is likely to be broken down. Explanation: The original resistance value is qualified.
Therefore, when choosing a megohmmeter, it is necessary to determine the range of the megohmmeter according to the withstand voltage level of the electrical appliance under test. Choose a 500 megohmmeter below 500V, and choose a 1000-2500 megohmmeter above 500V.
Megohmmeter selection requirements:
Choose the megohmmeter according to the measured object and the rated working voltage. The megohmmeter is classified according to the output voltage. The commonly used specifications include 250V, 500V, 1000V, 2500V, 5000V and other models.
When the working voltage of the measured object is low, you can choose a 250V megohmmeter. Most of the AC power supply in our country is three-phase 380V (single-phase 220V), and a 500V megohmmeter is generally used, which is also a necessary measuring instrument for the majority of electricians and home appliance maintenance personnel. However, 1000V, 2500V, and 5000V are mainly used on electrical equipment lines with high working voltage, and are used by electrical testing professionals.
The initial reading of some megohmmeters is not zero, but 1MΩ or 2MΩ. If this type of megohmmeter is used to measure electrical equipment, household appliances or lines in a humid environment, it may cause a false reading of zero megohm. sentenced.
Therefore, general electricians and home appliance maintenance personnel should choose a megohmmeter with a measurement range of 0-200MΩ or 0-500MΩ when choosing a megohmmeter.
