Why does the fan have no capacitance, I can t see the capacitor when I disassemble the electric fan,

There are many types of motors we usually use, including single-phase motors.

Shaded pole motors, series motors, etc.? Only single-phase motors have a starter capacitor, and several other types of motors do not require a starter capacitor. This electric fan of yours.

It is possible to use a shaded pole motor, which has a short-circuit ring (indicated by the arrow) as the starting coil to make the stator.

Generating a bias drive rotor to turn. The physical picture is as follows:

1] The capacitor taken from an electrical appliance such as an electric fan must be short-circuited and discharged before the test, otherwise the residual high voltage on it is likely to damage the capacitance meter. You need to test it with an ordinary good capacitor of several micro-methods to see if the capacitance test file of the capacitance meter is damaged; 2] The internal resistance of each resistance file of the multimeter is different, and the internal resistance of a large range is larger than that of a small range. So when you test with the highest range of 2000 megaohms, because the internal resistance of the multimeter is large, it and the capacitor charge and discharge time is longer, you can see the change of the display content, when you use a small range test, the charge and discharge time of the capacitor is short, plus the response speed of the digital meter is slow, so you can't see this process; 3] The capacitor you talked about at the last time will have a smaller value, it may be that there is a problem with the capacitor (but this is rare), could it be that your fingers touch two watch pens at the same time (that is, the insulation between the watch pens is not good)?

Fans that use AC directly have capacitors, while rechargeable fans do not.

This electric fan of yours.

If there is no starting capacitor, then the motor used in this electric fan is not a single-phase motor.

It is possible that there are other types of motors:

This type of motor does not require a starting capacitor and has only one coil in the motor.

2. Series motor. This kind of motor is an AC and DC dual-purpose motor, circuit diagram.

As follows: <>

Your electric fan.

After replacing the starting capacitor, it still can't start, and the fault is as follows:

1. As we all know, the motor is a single-phase motor.

There is a group of starting coils in the single-phase motor, if the buzz after power-on, the fan does not rotate, can not start, first of all, the motor bearing lubrication is not good, the motor rotor bearings at both ends of the dry grinding, the resistance increases, it is difficult to start, sometimes it is good to dial it by hand, it is recommended to maintain it frequently, and fill the bearing with lubricating oil frequently.

2. The wire in the starting capacitor connection line has been broken and fallen off, and it has not been found, check whether the capacitor connection is firm.

Due to the fact that the starting coil is not open (open circuit), short circuit, and blackened (starting coil 3 4 in the figure), the motor cannot be started, indicating that the motor has been broken, and it is recommended to rewind the motor coil, or replace the motor of the same type.

4. The motor bearing is seriously worn, the radial clearance is too large, the motor rotor and the stator have the phenomenon of rubbing against each other, and after being energized, under the action of electromagnetism, they firmly adsorb each other, resulting in the rotor can not rotate, and it is recommended to replace the motor bearing.

5. Because the wire diameter of the transmission line is too thin and the voltage drop is too large, the mains voltage is too low (it is best to use a multimeter.

Measurement measurement), the fan cannot be started.

If the fan blade is flexible and cannot be started when the power is turned on (the temperature rise of the fan motor will rise for a while), it can be considered that the capacitor may be damaged, or the fan blade can be operated normally after the power is turned on (after a boost), and then it can be confirmed that the capacitor is damaged (or the motor starting coil is damaged).

Determine whether the new capacitor is good, try to change another one, if it doesn't work, it means that the motor starts the coil and opens the circuit, turn the shaft by hand when powering the motor to see if the motor can turn.

First of all, when there is no power, you should flip the blade by hand to see if the rotation is flexible?

If there is resistance to rotation, it should be caused by serious wear of the motor bearing or dry lubricating oil, and it should be replaced with a new bearing or lubricating grease to make it rotate flexibly without resistance.

If the rotation is flexible and there is no resistance, and the capacitor is also replaced, it should be that the motor coil has an inter-turn short circuit fault, and the motor should be replaced with a new one. You can use a multimeter to measure the resistance of the coil to judge the quality of the coil.

It may not be that the capacitor is broken, and most of the problems with the fan not rotating are that the motor is broken, so try to change the motor.

In this case, measure the motor to see if it is normal, whether the capacitance capacity is normal, and whether the bearing has grease

First of all, turn the motor shaft or fan blade by hand without power to see if the rotation is flexible? If there is resistance to rotation, it means that the motor bearing is seriously worn or the lubricating oil is dry, and the new bearing should be replaced or lubricated to make it rotate flexibly without resistance. When installing the fixed motor, it is necessary to tighten the screws diagonally, and it must be tightened gradually, not in one step, and at the same time, it is necessary to hit the shaft back and forth with a wooden handle driver to ensure that the shaft is concentric with the bearings at both ends, so that the rotation will be flexible and without resistance after fastening.

If it turns flexibly without resistance, there are several reasons:

First, the capacitor is damaged, and a new capacitor of the same capacity should be replaced.

The second is that there is an inter-turn short-circuit fault in the coil, and the resistance value of the running winding and the starting winding can be measured with a multimeter to judge the quality of the winding. If the resistance value is abnormal, it is necessary to replace the motor with a new one.

That's when the motor coil is broken.

How to judge the quality of the fan capacitance:

1. Measure with a pointer multimeter.

Turn the switch to the K range, and touch the positive and negative poles of the capacitor with the watch hand to see if the capacitor is discharged.

If the watch hand swings to the right and retreats to the left, it proves that the capacitance accident is good; If the watch hand is slowly withdrawn to a certain position after swinging, it proves that the capacitor has leakage and should be repaired in time.

2. Measure with a digital capacitance meter.

Compared with the pointer multimeter, this operation is simpler, first touch the positive and negative poles of the capacitance meter to the positive and negative poles of the capacitance respectively. The value is close to or equal to the nominal value of the capacitance of the capacitor housing, which proves that the capacitor is not damaged and can continue to be used; If the value is significantly lower than the nominal capacity of the capacitor housing, it proves that the capacitor has been damaged and should be replaced with a new one in time.

3. Short with two wires.

Connect the measurement non-short-circuit capacitor into the 220V hole, let the capacitor be charged first, and short the two wires on the capacitor, if you hear a snapping sound and an electric spark, it proves that the capacitor is good. If there are no sparks, the capacitor is damaged.

How to choose the capacitor of the electric fan

1. Because electric fans also have different powers, the capacitor size selected is also different. There are many capacitor models on the market, if your electric fan power is 40 watts, you can choose between 1 capacitor model.

2. If the power is slightly larger, and the electric fan reaches about 70 watts, the capacitance should be larger, and the 2uf one should be chosen. There is also an electric fan with a power of 180 watts, which may be a ceiling fan, and the capacitor chosen is 3uf.

3. When choosing, you must pay attention to the capacitance should not be too large, otherwise it will damage the motor. However, if the capacitance is too small, it will make the electric fan unable to rotate, generally speaking, it should not exceed 20%.

Summary. Hello, glad to answer for you.

Because the alternating current used in household electric fans is single-phase, single-phase electricity cannot produce a rotating magnetic field, and the capacitor or inductor has a phase-shifting effect, and the single-phase electricity after passing through the capacitor will be moved by an electrical angle of 90°, so after adding the fan winding, it will form a rotating magnetic field with the single-phase electricity without phase shifting. Therefore, without capacitors, the windings of the electric fan will only be single-phase electricity, and it will definitely not be able to rotate.

Why do fans have no capacitance?

Hello, I have seen your question and am sorting out the answer, please wait for a while Hello, I am happy to answer for you. Because the alternating current used in household electric fans is single-phase, single-phase electricity cannot produce a rotating magnetic field, and the capacitor or inductor has a phase-shifting effect, and the single-phase electricity after passing through the capacitor will be moved by 90 ° of the undefeated electric angle, so after adding the fan winding, it will form a rotating magnetic field with the single-phase electricity without phase shifting. Therefore, there is no dry line, there is a capacitor, and the winding of the electric dry fan will only add single-phase electricity, and it will definitely not be able to rotate.

Thanks. You are welcome.

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First of all, it is necessary to determine what the problem is, not necessarily the capacitor, there are other problems that will cause the fan to not rotate.

First of all, in the case of no power, turn the fan blades by hand to see if it can be easily rotated, if the rotation is relatively tight, or it is difficult to rotate, what the shaft is stuck, you can first add a few drops of oil or clothes car oil to the bearing of the shaft, and constantly rotate the shaft, so that the shaft can easily rotate until it is turned on, and then power on, if the capacitor of the same specification capacity has been replaced, there should be no problem, you can start and use normally.

If the shaft rotates flexibly, and the capacitor is changed or cannot be used, it means that the motor winding has an open circuit between turns, that is to say, the coil is burned out, and then it can only be replaced by a fan motor, which is generally about 20 30 yuan for a fan motor of the same specification.

If the fan motor is used for a long time (more than two summers), you can fill up the oil at the front and rear end covers, generally about 5 drops of oil. If the fan is not very long, just add oil to the front cover.

First of all, check that the fan is not powered on, if the fan shaft rotates very tightly, you can add oil until it is loose and free. If you change the capacitor or not, you should check whether the windings of the fan tung motor are normal, and when it is normal, the resistance value of each winding should increase or fall in a step, but there can be no open circuit.

Or short circuit, the resistance value can not be big and small and unstable state, otherwise the motor is broken.

It can also be a problem with the starting circuit of the motor, which can also occur if there is a problem with the capacitor itself or if the capacity is not right.