How to use a megohmmeter to tell if the motor is burned out

The exterior consists of three end buttons, namely the line (L), the ground wire (E), and the shield wiring (protection ring G).

Megohmmeter principle: when the handle is shaken evenly at a speed of 120 rpm, the DC generator in the meter outputs the rated voltage of the meter, there is a current i1 between the circle 1 and the resistance to be measured, there is a current i2 between the circle 2 and the additional resistance r2 in the meter, the two currents act with the magnetic field to produce opposite moments, when the current of i1 is the largest (that is, the resistance to be measured is 0), the pointer points to the scale 0. When the I2 current is maximum (i.e. open circuit state), the pointer points to the scale infinity, when the measured resistance is a certain value, the pointer refers to the value of the measured resistance, because the megohmmeter has no hairspring, can not produce a reaction moment, so the megohmmeter stays in any position (i.e., does not position) when it is not measured, instead of returning to zero, which is different from other pointer instruments.

That's how a megohmmeter works. The situation you are talking about should be that the generator inside the megohmmeter is damaged and cannot generate voltage.

The first floor is. Maybe he just wanted to grab the couch quickly. Ha ha. I didn't even see the landlord's problem.

1.Use a shake to check whether the coil of the phase winding is on the ground (that is, between the incoming wire and the casing). (Because the main function of the shake table is to see the strength of the insulating material, it can only be said here to be a general judgment).

2.If the resistance to ground is less than 1 megawatt. It's dangerous. If it is less than, then it is specified to burn. And it's burned very badly.

3.If it is said that the resistance to ground is larger. Then measure between the two phases.

If it is a three-phase motor, it is a star-shaped connection, and the short-circuit copper sheet in the junction box is taken down first. Then measure the resistance between the two phases. Let's see if there is a resistance value less than the three-phase winding.

If there is. Then the motor burns.

All we can say is that this is a shoddy test. Because I want to know if it burned. It can be seen correctly with a meter measuring resistance. There are three things you must know here.

4.If it is said to be measured at 1 time. Turning the watch can hit 0Then the bad ones are more serious. Either it's just somehow relatively. Either that or all of them burned down.

5.If it is said that when measuring 3. It's relatively fine. The relative phase-to-phase resistance is very low. Even to 0, then it can only indicate a short circuit between phases.

6.That's right. When you have tested it above, it will be fine.

Also measure both ends of the same phase winding. It doesn't work. If not.

It may be an open winding. If it makes sense, then I will take a look at the data I have just measured. It's the insulation that has been lowered.

Or the motor burned out.

7.Here, I want to say a little. Some people.

For example, the first floor. I talked a lot about what the principle is. That's useless.

In practical working use. The table should be shaken gently. When you see that the watch hand is pointing to infinity, it can slowly accelerate to 120 rpm.

When you see the hand pointing to 0, don't shake it for long periods of time or at an accelerated rate. Otherwise, there will be problems with the inside of the table.

Use the "line" of the megohmmeter to terminate the winding lead wire of the motor "grounding" to terminate the shell of the motor, how to shake the handle not to say, and then remove the connecting piece on the binding post of the motor, "line" and "grounding" are respectively connected to the winding of the u, v, w, any two of the phase insulation, below the megohm can not be used.

Megohmmeters usually measure the insulation resistance between the windings of the motor and between the windings and the housing, and cannot accurately measure the short circuit of the windings. Measurement method reference.

Look at what kind of motor it is.

Generally, a megohmmeter is used to measure the motor, mainly to measure whether there is a short circuit or leakage between the coil and the shell, if the impedance between the coil and the shell is very small, then there may be a short circuit or leakage.

Summary. Motor damage is rarely a complete inter-turn short circuit, as long as the motor is connected to the power supply, there will be a large short-circuit current, the circuit breaker will also act instantaneously, and the arc extinguishing cover will have obvious sparks caused by short-circuit current. Therefore, after the single-phase motor is damaged, you can try to power on to judge the fault.

If there is no response from the motor after power-on, it can be basically judged that the line is broken. There is no power, one wire is broken, or two wires are broken.

Hello dear, you can power on again to see if there is a spark, if there is a spark, it is burned, or there is a smell.

As long as the motor is connected to the power supply, there will be a large short-circuit current, the circuit breaker will also act instantaneously, and the arc extinguishing cover will have obvious sparks caused by short-circuit current. Therefore, after the single-phase motor is damaged, you can try to power on to judge the fault. If there is no response from the motor after power-on, it can be basically judged that the line is broken.

There is no power supply, a wire is broken, or the car is high and two lines are broken.

1.Brief introduction.

Burnout is one of the more common problems in the use of electric motors. There are many reasons why a motor burns out, it could be that the motor is overloaded or the circuit is damaged. To determine whether the motor is burned out, it is necessary to use an instrument to measure.

This article will take a multimeter as an example to explain how to use a multimeter to measure the state of a motor.

2.Tools and equipment needed.

First of all, we need to prepare a multimeter to measure the state of the motor. In addition to this, we also need to have some wires and plugs on hand so that they can be connected for measurement.

3.Measure the over-width Sun Cheng.

In the first step, we need to disconnect the motor from the power supply and remove the housing of the motor. Next, we need to plug in two wires at each end of the motor, paying attention to the connection of the positive and negative poles.

In the second step, set the multimeter to the resistance setting, and then connect the wiring plug to the electrodes of the multimeter. Next, we need to connect the black electrode to one port of the motor, and the red electrode to the other port of the motor.

Step 3: Press the test button of the multimeter to check if the reading is zero. If the reading is zero, then there is no problem with the motor and it does not need to be replaced. If the reading is not zero, then the motor may have burned out.

Fourth, next we need to test the insulation of the motor. Adjust the multimeter to the voltage level and connect the black electrode to one port of the motor and the red electrode to the other port of the motor. Then press the test button, if the reading shows infinity or a very high resistance value, it means that the motor insulation is damaged and the motor needs to be replaced.

4.Precautions for use.

When testing a motor with a multimeter, you need to pay attention to the following:

1.Before testing the motor, it is necessary to make sure that the motor has been disconnected from the power supply and that the housing of the motor is removed.

2.When connecting the wires, pay attention to the connection of the positive and negative poles.

3.When measuring a motor, it is important to select the correct test gear, otherwise the test results may not be accurate.

4.After the measurement, unplug the power supply and test instrument.

5.Summary.

This article describes how to use a multimeter to detect whether the motor is burned out. By measuring the resistance and insulation of the motor through a multimeter, you can quickly determine whether the motor needs to be replaced. At the same time, there are some safety and operational matters that need to be paid attention to when using a multimeter for measurement.

The insulation resistance between the windings of the motor and to ground should not be less than a megaohm (500 kohms).

In the general low-voltage line (400V level and below), the newly laid line should not be less than a megaohm (between lines and lines, lines and ground); The insulation resistance between the equipment and lines in operation and to the ground should not be less than 1 trillion ohms or 1 thousand ohms.

For the motor with a rated voltage of 380V, use a 500V or 1000V shake meter (megohmmeter) to measure to the ground, and if it is greater than that, it is considered normal (the bigger the better). The 6KV motor should use 1000V-2500V shake meter to measure the insulation resistance, and its value should not be less than 6M. The 380V motor uses a 500V shake meter to measure the insulation resistance, and its value should not be lower.

Motor insulation includes the following:

The main insulation of the motor coil refers to the insulation between the coil and other windings, and the various insulating components and connecting wires and lead wires used for various supports or fixed use at the end are extremely wide.

When measuring insulation resistance with a megohmmeter, the motor insulation is affected by electrical, thermal, and mechanical forces and different environmental conditions, and the insulation will gradually deteriorate. Therefore, the motor with a voltage below 500 volts is usually measured with a 500 volt megohmmeter, and the insulation resistance value between each two-phase winding and each phase winding and the casing is measured to judge the insulation performance of the motor.

The motor insulation structure is to play the role of power insulation, the basic factors of the insulation damage of the motor coil are the influence of heat, electricity, mechanical force and environmental conditions, enhance the mechanical energy of the film, can improve the motor tear strength and surface stiffness to improve the use of process performance.

Summary. The multimeter measures whether the motor burns out, first of all, it is necessary to figure out whether the pump motor is a three-phase motor or a single-phase motor, and the measurement method is different. 1. The measurement method of the three-phase motor hits the multimeter to the 200 ohm block of the electric resistance.

Measure the three-phase resistance value separately, generally the resistance value of the 750 watt motor is about 20 ohms, and the resistance value of the 4000 watt motor is 3 5 ohms, and the resistance value is slightly different according to the different motors. If the resistance value of the three phases is the same and the difference is not large, it can be preliminarily judged that the three-phase winding is basically normal and there is no inter-turn short circuit.

The multimeter measures whether the motor burns out, first of all, it is necessary to figure out whether the electric brother of the water pump is a three-phase motor or a single-phase motor, and the measurement method is different. 1. The measurement method of the three-phase motor hits the multimeter to the 200 ohm block of the electric resistance. Measure the three-phase resistance value separately, generally the resistance value of the 750 watt motor is about 20 ohms, and the resistance value of the 4000 watt motor is 3 5 ohms, and the resistance value is slightly different according to the different motors.

If the resistance value of the three phases is the same and the difference is not large, it can be preliminarily judged that the winding of the three phases is basically normal and there is no inter-turn short circuit.

Generally, a megohmmeter is used to measure the insulation resistance value of the motor, and the insulation resistance value between each two-phase winding and each phase winding and the casing should be measured to judge the insulation performance of the motor.

When using a megohmmeter to measure insulation resistance, a 500 volt megohmmeter is usually used to measure motors with voltages below 500 volts; Motors with a voltage of 500 to 1000 volts are measured with a 1000 volt megohmmeter. Motors with voltages above 1000 volts are measured with a 2500 volt megohmmeter.

Under the condition of thermal state (75), the insulation resistance value of the general small and medium-sized low-voltage motor should not be less than 0

5 megaohms, the insulation resistance value of the stator per kilovolt working voltage of the high-voltage motor shall not be less than 1 megaohm, and the insulation resistance value of the winding rotor winding per kilovolt working voltage shall not be less than 0

5 megaohms; The insulation resistance of the secondary circuit of the motor should not be less than 1 megaohm.

The steps to measure the insulation resistance of the motor are as follows:

1) Disassemble the coupling pieces of the 6 ends in the motor junction box.

2) Lay the megohmmeter flat, unwired first, and shake the megohmmeter. The watch hand should point to the " place, and then the two binding posts with "L" (line) and "E" (grounding) on the table should be shorted with a test clamp with a wire, and slowly shake the handle, and the watch hand should point to the "0".

3) Measure the resistance between the three-phase windings of the motor. Connect the two test clips to either end of any two-phase winding, lay the watch flat, shake the megohmmeter at a constant speed of 120 revolutions per minute for one minute, and read the stable indication value of the watch hand.

4) Using the same method, measure the insulation resistance value of each phase winding phase and the casing in turn. However, it should be noted that the binding posts marked "E" or "Grounded" on the table should be connected to the uninsulated place on the casing.

The insulation between the phases and the insulation to the ground must be greater than the motor is good!

Summary. What are the requirements for motor insulation resistance?

a) The stator coil of the high-voltage motor is measured with a 2500V megohmmeter, and its insulation resistance value is not less than 1m per kilovolt;

b) The stator coil of the low-voltage motor is measured with a 500V megohmmeter, and the resistance value is not less than;

c) The stator coil of the DC motor is measured with a 1000V megohmmeter, and the resistance value is not lower than that;

d) The measured value should be compared with the previous value at the same temperature, and if it is lower than 70% of the previously measured value, the cause should be ascertained.

e) Absorption ratio r60 "r15", the ratio is not less than.

Motor insulation measurement method.

The first step is to correctly select its voltage and measurement range.

The megohmmeter should not be used indiscriminately, and it should be selected according to the voltage of its measuring equipment. Usually 500V below to 100V electrical equipment or circuits, use 500V 100m and above megohmmeter, if you measure the insulation resistance of the motor, choose 500V 100M megohmmeter.

Can you use a 500 megger to detect a 220 motor?

What are the requirements for motor insulation resistance? a) The stator coil of the high-voltage motor is measured with a 2500V megohmmeter, and its insulation resistance value is not less than 1m per kilovolt; b) The stator coil of the low-voltage electric vending machine is measured with a 500V megaohm differential comma, and the resistance value is not less than that; c) The stator coil of the DC motor is measured with a 1000V megohmmeter, and the resistance value is not lower than that; d) The measured value should be compared with the previous value at the same temperature, and if it is lower than 70% of the previously measured value, the cause should be ascertained. e) Absorption ratio r60 "r15", the ratio is not less than.

The first step of the motor insulation measurement method is to correctly select its voltage and measurement range, and the megohmmeter can not be used indiscriminately, but should be selected according to the voltage of the measuring equipment. Usually 500V below to 100V electrical equipment or circuits, use 500V 100m and above megohmmeter, if you measure the insulation resistance of the motor, choose 500V 100M megohmmeter.

2. The insulation resistance between the windings measured by the megohmmeter is used to measure the insulation resistance between the windings of the motor using a megohmmeter (500V), and the measurement is shown in Figure 2. When measuring, remove the thick or terminal block and the connecting piece between the power line and the terminal, connect the L measuring wire of the megohmmeter to a phase winding and a terminal block, and the E measuring wire is connected to a terminal of another phase winding, and then shake the handle of the megohmmeter to measure, the insulation resistance in the middle of the winding code is greater than 1m to be qualified, and the minimum can not be lower. Then use the same method to measure the insulation resistance between other phases, if the insulation resistance of the winding to the ground is unqualified, it should be dried and re-measured, and it can be used only when it is qualified.

With 500V quietly shaking the meter, the insulation level of the motor is generally to take into account the voltage and power of the base motor, 1000V can also be used to measure 220V, 380V motor, but many people do not grasp the speed of the shake meter (too fast) when measuring, but the insulation of the motor is broken down! Because of this, it is best to use 500V to measure 220V and not to complicate things.