How to judge the head and tail of a three phase asynchronous motor

There are three ways to use a multimeter, a shake meter or a micro-ampere meter to determine the beginning and end of the six wires

Method 1: 1 Use the electric resistance of the shake meter or multimeter to find the two wires of each phase of the three-phase winding

2. First make the assumption number U1 and U2 for the wire end of the three-phase winding; V1, V2 and W1, W2 are connected together to form a two-phase winding series

3 u1, v2 wire with a light bulb on the end

4 W1, W2 two wires on the 36V AC power supply, if the bulb shines or with a meter to measure U1, V2 two wires have voltage, indicating that the number of the wire head U1, U2 and V1, V2 is correct If it does not emit light, or the voltage can not be measured with a multimeter, then the number of any two wires of U1, U2 or V1, V2 can be reversed

5. Then according to the above method, W1 and W2 two wire ends are distinguished

Method 2: 1 First, use the shake meter or multimeter block to find out the two wires of each phase of the three-phase stator winding

2. Assume that the windings of each phase are numbered as U1 and U2; v1，v2；w1，w2．

3. Connect the hypothetical U1, V1, and W1 together, and U2, V2, and W2 together, and measure these two wires with a multimeter (adjusted to the micro ampere) Turn the motor rotor by hand, if the multimeter (micro amplitude) pointer does not move, then the hypothetical number is proved to be correct; If the pointer is deflected, it means that one of the prime ministers is assumed to have the wrong number, and it should be remeasured one by one until it is correct

Method 3: 1 First distinguish the two wires of each phase of the three-phase winding, and make a hypothetical number, then connect the negative pole of the battery to U1, the positive pole is connected to U2 through the switch, and measure W1 to the positive electrode and W2 to the negative electrode with a multimeter

2 When the switch is closed, pay special attention to the direction of the swing of the pointer of the multimeter (micro ampere), if the pointer is deflected in the positive direction, the wire end connected to the positive pole of the battery and the wire end connected to the negative pole of the multimeter are the same name end (the same is the first end or the end) If the pointer is deflected in the negative direction, the wire end connected to the positive pole of the battery and the wire end connected to the positive pole of the multimeter are the same name end

3 Then connect the battery and the switch to the other phase of the two wires for testing, and the head and end of each phase can be correctly determined

It is generally marked on the junction box.

Regardless of the head and tail, the three-phase coil is the same.

Measure it with a multimeter.

Three-phase asynchronous motor this skin.

How to judge the good and bad:

1. Shake the watch. Shake: 500V shake the meter, shake the insulation resistance of the wire on the three binding posts to the motor shell, it should be above the euro, it means that there is no short circuit to the ground.

2. Multimeter.

Measurement: Measure the resistance between the three phases of ab c, whether it is equal, it should be about the same, and the difference is too much, but it will not take long, remember that the larger the motor, the smaller the resistance! Grip the belt but not all three phases are 0 ohms, unless you are particularly large, such as a motor above 50kw!

Remember that if it is the 6 terminals of the speed regulating motor.

The resistance value is not the same!

3. Check the bearings and fans, and generally wrap the motor to let them all be replaced! Because sometimes the bearing will burn the motor!

4. The no-load current of the motor is generally the rated current.

10% of 50%, sometimes the motor idling current is still zero!

5. When the rated current of the motor is running, it is running at full load and the output power is output.

It's basically 100%. The running current is small, which means that the output power of the motor becomes smaller, and it is a light load operation.

When the conductor cuts the magnetic field lines in the magnetic field, the induced current in the conductor will be generated, which will produce a rotating magnetic field, which will cut the rotor windings, thereby generating an induced current in the rotor windings.

The current-carrying rotor conductor will generate an electromagnetic force under the action of the stator rotating magnetic field, which will form an electromagnetic torque on the motor shaft, drive the motor to rotate, and the motor will rotate in the same direction as the rotating magnetic field.

How to dig the head and tail sequence of the three-phase motor, and how to detect the stator winding of the three-phase motor and its head and tail end.

1. Stator winding of three-phase motor Identification of three-phase motor The three-phase motor has three stator windings, each winding has two lead-out wires, and there are a total of six lead-out wires. Measuring the on-off with a multimeter can find out the two lead-out wires for each winding. The beginning and tail of the stator winding of the two-phase and three-phase motor can be further judged under the condition that the two lead wires of each winding of the three-phase motor are determined.

Measurement method 1: (1) Multimeter selection: DC 50 (2) Measurement process:

1. Connect one lead wire from each of the three windings of the motor together, and connect the remaining three lead wires (one for each winding) together. Do this into two sets of leadouts. Wrap two sets of lead-out wires around the two table pens of the multimeter.

Turn the motor rotor by hand, and observe the multimeter pointer at the same time, if the pointer does not deflect (swing), it means that the three wires connected together are the same three-phase winding head (or tail) lead wire, and the test is over. If the pointer is deflected (wobble), it means that one of the windings is reversed, and the next step of the test continues. 2. Swap the two lead-out wires of either winding, (Note:

Remember which winding is in tune. This makes two sets of lead-outs. Repeat the above test:

Wrap the two sets of lead-out wires around the Chai Na two meter pen of the multimeter. Turn the motor rotor by hand, and observe the multimeter pointer at the same time, if the pointer does not deflect (swing), it means that the three wires connected together are the same three-phase winding head (or tail) lead wire, and the test is over. If the pointer is deflected (wobble), it means that one of the windings is reversed, and the next step of the test continues.

3. Then the two lead-out wires of either winding in the remaining two windings are reversed, so that two sets of lead-out wires are made again. Repeat the above test: Wrap the two sets of lead-out wires around the two table pens of the multimeter.

Turn the rotor of the motor by hand, and observe the multimeter pointer at the same time, if the pointer does not deflect (swing), it means that the three wires connected together are the same as the three-phase winding judgment of the first end (or tail end) of this group, and the test is over. If the pointer is deflected (wobble), it means that one of the windings is reversed, and the next step of the test continues. 4. Restore the two leads of the first reversal (and then readjust).

At this time, the three wires connected together are the first (or tail) lead-out wires of the three-phase winding, and the test is completed. It can be verified by the method described above: two sets of lead-out wires are wound around the two meter pens of the multimeter.

Turn the motor rotor by hand while observing the multimeter pointer, which will not deflect (swing). Indicates that the judgment is correct. Measurement method two:

1) Multimeter selection: DC 50 (2) Measurement process: 1. Connect the two lead wires of one winding of the motor to the two meter pens of the multimeter respectively, and connect one lead wire of the other winding to one pole of the battery, and the other lead wire to touch the other pole of the battery, and pay attention to the deflection of the pointer of the multimeter at the same time

If the pointer is deflected in the positive direction, it means that the wiring of the positive pole of the battery is the same as the wiring of the negative pole (black pen) of the multimeter (black watch pen), and the other two lead wires are the same tail end (or the first end). If the pointer is reversed to deflect, it is explained.

1...The rotor is generally not a problem, 2....Generally, the stator winding is detected, and the resistance of the multimeter is measured in the three-phase resistance, and the resistance between the three phases should be the same, and the resistance deviation of more than 1kw does not exceed the ohm.

Use a shake meter (i.e. a megohmmeter) to measure the resistance of three relative to the ground, and it is written in the book that the value is faster than the megaohm, but it cannot be used if it is less than 10 megaohms on the real socks Chang group, and it is always tripping. . .

3...Check the bearing situation, whether it is a lack of oil, whether the steel ball is deformed, usually the bearing is damaged will hear the motor has an abnormal sound...

4...Don't you give points?

How to judge the quality of three-phase asynchronous winding motorFirst of all, let's summarize how to determine the three-phase asynchronous motor.

The quality of the coil, what instrument to use to check:

1. Multimeter: used to check the measurement of motor coil on-off.

2. Single-arm bridge: accurately measure the resistance of the coil, and you can know whether the electric resistance of each phase coil is close.

3. Megohmmeter: used to measure the insulation resistance of the motor between phases and between phases to the ground, not too low to less than megohm. Using a 500V megohmmeter to measure the insulation resistance is greater than the indication is good, and lower than the motor is broken, but this is only an appearance judgment, for the inter-turn short circuit interphase breakdown only disassembly inspection.

The stator and rotor may be burned, and the stator measurement method; Use a three-purpose meter to measure whether the phases are passable, if it is not passed, it is broken, and the insulation resistance of the spine winding to the motor shell is generally at least greater than the megaohm, otherwise it can not be used. The rotor is generally not very easy to break, the measurement method; Take out the carbon brush, use the three-purpose meter to measure whether the three slip rings are passable, and if they are not passed, they will be broken, and the slip rings are insulated with the swing table to insulate the motor shell, and the number of grandchildren is greater than the megaohm. The winding resistance of the motor is very small, and the winding resistance cannot be measured by the general three-purpose meter, and the reading is close to zero.

Power-on test method: first use the ohmic file of the multimeter to divide the six lead heads into three groups, and then connect any two groups in series to the AC power supply, and connect a bulb in series on the third group (15 or 25W, high power is not lit). After power-on, if the bulb is on, it means that the two groups in series are connected end to end; If the bulb does not light up, it means that the tail is connected or the head is connected, and so on.

Battery orientation method: first divide the six lead ends into three groups with the ohmic gear of the multimeter, then connect the two wires of the first group to the positive and negative poles of the milliampere file of the multimeter respectively, press the first wire of the second group on the negative pole of the dry battery with your finger and touch the positive pole of the battery with the other end, if the pointer of the multimeter is biased to the right side;

Indicate that the positive end of the multimeter and the number of negative pole ends of the dry battery are the head (tail), if the pointer is biased to the left, it means that the positive end of the multimeter and the positive end of the dry battery are the head (tail), and so on.

Steering method: for small motors, the head and tail of the winding can also be judged without a multimeter, and the two wires are the same phase when distinguishing, and then each phase takes a wire end, connects the three heads into a point, and groundes the point, and connects the two 380V power cords to the two lead heads of the motor in order to observe the rotation direction of the motor.

If it is connected three times and the motor turns the same, it indicates that the three-phase head and tail wiring is correct; If the motor is reversed twice after three connections, it indicates that the windings of the phase that have participated in these two reversals are reversed. For example, the first phase A and B, the second phase B and C are reversed, and phase B participates twice, indicating that phase B is reversed, and the two wire ends of phase B can be reversed.

The two windings of the transformer are connected in parallel and connected in series with a light bulb on the AC power supply. The frequency of this AC power supply should be adapted to the transformer core, the iron core transformer uses the industrial frequency, and the switching transformer is powered by a switching power supply.

Swap the two ends of either winding and connect them with the bulb to power them up. When comparing the two connection methods, you will find that the brightness is different, and the connection method with the darker brightness is the terminal of the same name.

When the direction of magnetic flux is superimposed (in the same direction), the inflow end of the two windings is their eponymous end, and the current outflow end of the two brigade windings is their other set of eponymous ends.

You can use a multimeter to distinguish 6 wires, divide the two wires into one phase, and then divide the six wires into three phases, and then judge the head and tail of the winding, the specific method: the DC milliampere of the multimeter is hit to the smallest gear, and the meter pen is connected to a certain group of two ends of the three-phase winding, and the positive and negative poles of the battery are connected to the two wires of the other phase.

When the switch is closed, if the swing direction of the watch hand is greater than zero, it means that the wire end connected to the negative pole of the battery and the wire end connected to the positive pole of the multimeter (red) are the same name end (both can be regarded as the head). By analogy, the head and tail of the other two phases can be measured.

Compared with single-phase asynchronous motors, three-phase asynchronous motors have good running performance and can save various materials. According to the different rotor structures, three-phase asynchronous motors can be divided into cage type and winding type. The asynchronous motor of the cage rotor has a simple structure, reliable operation, light weight and low cost, and has been widely used, but its main disadvantage is that it is difficult to regulate the speed.