Insulation resistance test instrument The insulation resistance of the test equipment or circuit must be measured by a megohmmeter (digital megohmmeter or swing meter), not by a multimeter. Digital megohmmeter is a high voltage and easy to use test large resistance indicator meter. Its scale is measured in megohm, expressed in MQ. In the actual work, according to the measured object to choose different voltage levels and resistance measurement range of the instrument.
The principle for selecting the measuring range of digital megohmmeter is: The measuring range should not exceed the measured insulation resistance value too much to avoid large errors. The insulation resistance of electrical equipment or lines below 500V is generally measured on the construction site. Therefore, most of the 500V, resistance measurement range of 0-250m ω digital megohm meter. Digital megohmmeter has three terminals: L(line), E(ground) and G(shield). These three terminals are selected according to different measurement objects.
Test method for insulation resistance of electrical equipment and facilities
First, disconnect the power supply and measure the insulation resistance of the stator windings of the three-phase asynchronous motor to the shell (i.e. relative ground) and between the three-phase windings. Pendulum measurement of three phase stepping motor rotor winding measurement of relative phase. When measuring relative ground, "E test line is connected to motor shell water L" test line is connected to three-phase winding. That is, the three-phase winding of a shell test; If unqualified, separate the single phase with digital megohmmeter test; When measuring the relative phase, the phase coupling should be removed.
Several cases in which an insulation resistance test is required
1. Before the newly installed electrical equipment is put into operation;
2. Equipment that has not been used for a long time or before being used again after being discontinued for more than 3 months;
3. When the motor is overhauled or fails;
4, mobile electrical equipment (such as: grindstone machine, submersible pump, rammer, plate vibration engine, hose vibration engine, etc.) in the field before the first use;
5, hand-held power tools in addition to the first use before testing, after a period of regular testing;
6, safety isolation transformer (such as: running lamp transformer) before use.
Wuhan Xinshengneng Technology Co., Ltd. specializes in the production of grounding/insulation series of test equipment, the production of a variety of products, complete models, cost-effective products, welcome to call 0312-3188565 consultation!
