Multimeters, how easy and fast to test engine good and bad
With a multimeter to simply measure the motor is usually a common method in our work, with a multimeter to measure the motor is good or bad mainly with resistance block measurement and current block measurement of the two methods, the following I come to talk about how to use a multimeter to quickly and easily detect the motor is good or bad.
Use the multimeter to check my most common method is to check before the three-phase winding between the connecting wires apart, so that the three-phase motor windings are not connected to each other, and then the multimeter block to RX10K ohms block, and then the multimeter of a pen and the winding of one end of the connection, with the other pen and the motor casing is connected. At this time we can look at the multimeter indicates the size of the resistance, if the multimeter indicates the resistance value is very small, or even zero time, which indicates that the motor of this phase of the winding and the motor casing there is a grounding fault exists. If the measured resistance value is very large, then it shows that there is no ground fault.
We can also use the multimeter resistance block to measure the three have been independent of the winding, we first figure out the normal resistance of the three windings, in the measurement if the resistance of the three windings is the same, then it shows that the winding is normal, if the three independent windings of the resistance value of the difference, then it shows that the motor is not normal. Then you can use a shaking table (megohmmeter) to measure the insulation resistance value between the three windings of the motor. The resistance value between them is generally between 0.5 megohm and 1 megohm, which should belong to the normal value. Finally, the three windings were measured with a shaking table on the case (to ground) insulation. Normal resistance value should be in 0.5 megohm to 1 megohm or so should be normal.
Another method is to use the multimeter measurement is to use the multimeter current block, but can only be used in small three-phase motor, such as in the following 4KW three-phase asynchronous motor, which works when the rated current is in the 8.8 amperes of current. The current measurement value of our general multimeter is up to 10A range, if you go to measure the power of a larger motor, you can use a special clamp-on ammeter to measure. We use this method is mainly to measure the motor three-phase current is not balanced, if the current is not balanced, it means that the motor is also faulty.
In fact, in many cases, we can not use the multimeter to judge the basic condition of the motor, such as through the "see", "smell" and "touch" and so on can also be roughly judge the basic motor Failure, because the motor in the event of failure we can see from the situation in which it runs, such as the motor's speed suddenly slowed down, there is an abnormal noise, the surface temperature of the motor is too high, the motor shell charged, etc. are due to different faults caused by the motor.
