Do-it-yourself repair of household fans. Electrical circuit of the fan

Dear site visitors!!!

I believe that the information presented in this topic will be useful to you. The topic will address various issues in this area, and many questions arise in this area:

• How does a household fan electric motor work?
• how to replace a capacitor in a fan's electrical circuit;

how to rewind the fan motor stator, how to repair:

• wall fan;
• ceiling fan;
• window fan;
• floor fan;
• bathroom fan;
• kitchen fan;
• fan with timer;
• exhaust fan.

It is almost impossible to immediately and completely provide information on issues that arise related to malfunctions resulting from the operation of various types of electric fans.

The topic will gradually expand, that is, after a certain period of time, additions will be made.

Take an interest in various sources of information in this direction:

• technical sites;
• technical literature

and so on. Accumulate your experience and knowledge.

Connection diagram for motor via capacitor

There are 2 types of single-phase asynchronous motors - bifilar (with a starting winding) and capacitor. Their difference is that in bifilar single-phase motors the starting winding operates only until the motor accelerates. Afterwards it is turned off by a special device - a centrifugal switch or a start-up relay (in refrigerators). This is necessary because after overclocking it reduces efficiency.

In capacitor single-phase motors, the capacitor winding runs all the time. Two windings - the main and auxiliary, they are shifted relative to each other by 90°. Thanks to this, you can change the direction of rotation. The capacitor on such engines is usually attached to the housing and is easy to identify by this feature.

Connection diagram for a single-phase motor via a capacitor

When connecting a single-phase capacitor motor, there are several options for connection diagrams. Without capacitors, the electric motor hums, but does not start.

• 1 circuit - with a capacitor in the power supply circuit of the starting winding - starts well, but during operation the power it produces is far from rated, but much lower.
• 3, the connection circuit with a capacitor in the connection circuit of the working winding gives the opposite effect: not very good performance at start-up, but good performance. Accordingly, the first circuit is used in devices with heavy starting, and with a working capacitor - if good performance characteristics are needed.
• Diagram 2 - connecting a single-phase motor - install both capacitors. It turns out something between the options described above. This scheme is used most often. She's in the second picture. When organizing this circuit, you also need a PNVS type button, which will connect the capacitor only during the start time, until the motor “accelerates”. Then two windings will remain connected, with the auxiliary winding through a capacitor.

Connection diagram for a three-phase motor via a capacitor

Here, the voltage of 220 volts is distributed into 2 series-connected windings, where each is designed for this voltage. Therefore, the power is lost almost twice, but such an engine can be used in many low-power devices.

The maximum power of a 380 V motor in a 220 V network can be achieved using a delta connection. In addition to minimal power losses, the engine speed also remains unchanged. Here, each winding is used for its own operating voltage, hence the power.

It is important to remember: three-phase electric motors have higher efficiency than single-phase 220 V motors .
Therefore, if there is a 380 V input, be sure to connect to it - this will ensure more stable and economical operation of the devices. To start the motor, you will not need various starters and windings, because a rotating magnetic field appears in the stator immediately after connecting to a 380 V network.

Main causes of malfunction

Among the main reasons:

• Incorrect operation of the exhaust system. The engine may break due to improper handling of adjacent elements. For example, due to a clogged mesh filter that catches grease, the operation of the propulsion systems may be disrupted. The filter needs to be cleaned regularly, about once every three weeks. New models have an indicator light. When it lights up, then it is time to replace the filters. The signal is given during proper operation no earlier than after two years of engine operation.
• Failure to comply with basic operating rules. The exhaust fan must be turned on when the stove is turned off. If you start the air extractor while cooking, the motor may not withstand temperature changes and break (how to repair a kitchen hood fan with your own hands?). The hood should be turned on 2 minutes before cooking. And after finishing, turn it off after 15 minutes.
• Lost contacts. The engine runs with slight vibration, so poor-quality contacts may break. This usually happens in Chinese technology.
• Incorrect engine installation. Incorrect installation disrupts the air flow and clogs the engine slots with debris. This can happen due to a poor-quality connection of the wires in the terminal box or due to a strong bend in the corrugation (air duct).
• Problems with electrical wiring. Due to frequent short circuits or power outages, interference in the operation of the motor is possible, which leads to breakdown and improper operation.

Online calculation of motor capacitor capacity

Enter data for calculating capacitors - motor power and efficiency

There is a special formula that can be used to calculate the required capacity accurately, but you can easily get by with an online calculator or recommendations that are derived from many experiments:

The working capacitor is taken at the rate of 0.8 μF per 1 kW of engine power; The launcher is selected 2-3 times more.

Capacitors must be non-polar, that is, not electrolytic. The operating voltage of these capacitors must be at least 1.5 times higher than the network voltage, that is, for a 220 V network we take capacitors with an operating voltage of 350 V and higher. To make starting easier, look for a special capacitor in the starting circuit. They have the words Start or Starting in their markings.

Starting capacitors for motors

These capacitors can be selected using the method from smallest to largest. Having thus selected the average capacity, you can gradually add and monitor the operating mode of the engine so that it does not overheat and has enough power on the shaft. Also, the starting capacitor is selected by adding until it starts smoothly without delays.

During normal operation of three-phase asynchronous electric motors with capacitor start, connected to a single-phase network, it is assumed that the capacitance of the capacitor will change (decrease) with increasing shaft speed. At the moment of starting asynchronous motors (especially with a load on the shaft) in a 220 V network, an increased capacity of the phase-shifting capacitor is required.

Design of a typical floor fan

Do-it-yourself floor fan repair is on the agenda! You should start small: the simplest fans do not have a ground terminal. The device does not have a degree of electrical safety. The floor fan device includes a housing made of plastic. If water gets inside, expect a good shake. This type of floor fan should not be used near water. Starting with an aquarium with fish, ending with a flower vase. Particularly dangerous where small children live. If the thing falls, the child will guess to pour milk inside... Draw your own conclusions:

• the structure is unstable;
• the base breaks easily and bends;
• There is no protection against electric shock.

If a floor fan falls, there is a high probability that nothing will happen. Let's dive inside the structure. Let's leave aside for now the features of regulating the engine speed and buttons. Let's talk about the gearbox. The Krasnodar floor fan carries one asynchronous capacitor motor. The front side of the shaft is connected to the blades through a pin and a nut with a left-hand thread, the rear side goes to a gearbox formed by two gears, one double.

The shaft is equipped with a thread that engages the teeth of a large wheel as it rotates. The moment is transmitted to the small wheel, which drives the flywheel. The gear of the crank mechanism is the diameter of a hand, so the rotation is inferior to the speed of the original shaft of the asynchronous motor.

1. The blades spin at full motor speed.
2. The crank mechanism, thanks to the gearbox, moves more slowly.

Through the cardan transmission, the crank is hooked onto the leg, and the engine housing is mounted on the axle. When the shaft of an asynchronous motor rotates, the blades move smoothly in one direction or the other. However, you can stop the process. For a double gear, the roller is attached to the larger gear by two balls with a spring inserted into a through hole. If you pull the adjuster knob directly connected to the axle, the latch slides up. The connection between the gear and shaft is lost, and rotation stops. The mechanism provides fall protection: six grooves are cut into the inner mounting hole of the drive gear. Balls fit. There are six positions, the mutual transition is accompanied by a click, the axis rotates relative to the gear, the balls hit the walls, sliding into the grooves.

Clicking sounds are heard, there is a high probability that the floor fan has fallen. The drive is jammed, it works, clicking, a protective mechanism, protecting the motor from combustion.

We believe that the mode is unfavorable for a floor fan; if you do not turn off the device, the thermal fuse of the motor will certainly break. The gearbox is attached to the engine with three bolts and has a pair of lubrication holes through which the plastic gears can be lubricated. Refers to a drive rotating at the speed of an asynchronous motor.

Headache, how to fix a floor fan and assemble it. We see the situation: the relative position of the gearbox is incorrectly set, the legs through the gear, the head of the floor fan will move asymmetrically relative to the frontal plane. Can be annoying. Attach the gearbox, check the product by connecting power. Be careful not to get an electric shock, try to visually determine the correctness of the assembly.

Connection diagram and calculation of the starting capacitor

Failure of capacitors in the air conditioning compressor circuit is not so rare. Why do you need a capacitor at all and why is it there?

Low-power household air conditioners are mainly powered by a single-phase 220 V network. The most common motors used in air conditioners of this power are asynchronous with an auxiliary winding, they are called two-phase electric motors or capacitor motors .

In such motors, two windings are wound so that their magnetic poles are located at an angle of 90 degrees. These windings differ from each other in the number of turns and rated currents, and, accordingly, in internal resistance. But at the same time they are designed so that during operation they have the same power.

In the circuit of one of these windings, its manufacturers designate it as a starting winding, they include a working capacitor, which is constantly in the circuit. This capacitor is also called a phase-shifting capacitor, since it shifts the phase and creates a circular rotating magnetic field. The working or main winding is connected directly to the network.

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There are other schemes for connecting a motor through a capacitor, but we will consider these issues another time in another article.

Operating principle and startup scheme

Capacitors that are in a circuit can be charged. The required torque is provided by the displacement of phase currents in the windings of the IM. And in many cases, electrical equipment is driven by three-phase motors.

If you look at a plate where two currents are indicated through a fraction, it will be the smaller of them. The working capacitor is connected permanently in the winding circuit, the starting capacitor is closed briefly through the start switch. Installation and selection of components Capacitors have considerable dimensions, so they do not always fit into the inside of the boron junction box on the electric motor housing. It doesn’t make sense to immediately start calculating the connection diagram.

The capacity of the starting capacitor should be 2.5 - 3 times greater than the working capacitor. If the engine starts easily and has enough power to operate, then everything has been selected correctly. Everything is connected simply, it is fed into the thick wires. connecting a 380 to 220 volt motor

Calculation of the capacitance and voltage of the working capacitor

The calculation comes down to selecting such a capacitance so that at a rated load a circular magnetic field is provided, since at a value below or above the rated value the magnetic field changes its shape to an elliptical one, and this worsens the performance characteristics of the engine and reduces the starting torque. Engineering reference books provide a formula for calculating the capacitance of a capacitor:

Average = Isinφ/2 πf U n 2

I and sinφ – current and phase shift between voltage and current in a circuit with a rotating magnetic field without a capacitor

f- AC frequency

U – supply voltage

n - winding transformation coefficient, defined as the ratio of winding turns with and without a capacitor.

The voltage across the capacitor is calculated using the formula

Uc= U√(1+n 2 )

Uc - operating voltage of the capacitor

U - motor supply voltage

n - winding transformation ratio

The formula shows that the operating voltage of the phase-shifting capacitor is higher than the motor supply voltage.

Calculation manuals give an approximate calculation - 70-80 µF of capacitor capacity per 1 kW of electric motor power, and the capacitor voltage rating for a 220 V network is usually set at 450 V.

Also, a starting capacitor is connected in parallel to the working capacitor for the start-up period, for about three seconds, after which the relay is activated and turns off the starting capacitor. Currently, circuits with an additional starting capacitor are not used in air conditioners.

More powerful air conditioners use compressors with three-phase asynchronous motors; starting and running capacitors are not required for such motors.

How to disassemble a floor fan

From what has been said, it is clear: there is nothing to break inside the floor fan. This is a motor and a capacitor. The rest falls on the mechanical part, the gearbox. If there is whistling or noise, try lubricating the gears. How to do this is clear from what has been said. There are a couple of holes in the gearbox housing for these purposes. Solid oil is suitable for plastic parts.

Repairing a floor fan yourself shouldn't be too difficult. Replace the motor with one of suitable weight and size. The main types of breakdowns concern the mechanical part; restoration is carried out using conventional (welding plastic with polyethylene) methods with skilled hands.

Calculation of motor capacitor capacity

The winding with a smaller cross-section is the starting one. Such devices have a power factor greater than that of the short-circuited devices described above and develop greater torque in comparison with them. You can do this yourself or use online calculators. The circuit with a working capacitor does not provide for disconnecting the additional winding after starting and accelerating the engine.

If to connect an asynchronous motor you use not a three-phase network, but a household single-phase one, that is, power it through one winding, it will not work. Connecting capacitors (part 1)

Assembly

In conclusion, I note that during installation and operation, one should remember that there is no galvanic isolation of the device (a disadvantage compared to a transformer circuit) from a 220 volt network. Author of the article: Nikolay5739 (Kondratiev Nikolay, Donetsk.)

Connecting a single-phase electric motor: using a magnetic starter

But there is another way - connecting a single-phase electric motor as a generator to produce three-phase voltage.

The magnetic field of the main winding maintains rotation for a long time. The solution is to install a 3-pole switch. This procedure is implemented by simply changing the order in which the starting winding is turned on when it is connected to the working winding. This is due to the fact that when only the working winding C1-C2 is connected to the network, a single-phase capacitor motor will have a pulsating magnetic field rather than a rotating one, that is, it will not start. It is necessary to connect chokes to each of the network wires to eliminate interference.

The magnetic circuit of single-phase motors contains a two-phase winding, consisting of a main winding and a starting winding. Control of starting current indicators in such motors is carried out by a frequency converter. This will be one of the network wires. The most convenient is a magnetic starter controlled from alternating current. All containers included in the circuit must be of the same type.

If after this the engine turns out to be hot, then: The bearings may be dirty, jammed, or simply worn out. The idea of ​​​​using a starting capacitor is to include it in the circuit only at the moment the motor starts. Machines for processing raw materials, etc. Connecting a capacitor. How to connect a capacitor to an electric motor. Scheme.

Connecting a single-phase motor via a capacitor - 3 circuits

What happens with this?

If the heating is quite noticeable, then you need to look for its causes. If the capacity is significantly exceeded, intense heating will begin.

It is necessary that the rated voltage of the capacitor is equal to or greater than the calculated one. This is the optimal solution for achieving average performance. Afterwards it is turned off by a special device - a centrifugal switch or a start-up relay in refrigerators.

Secondly, and most importantly, the author was convinced in practice that even an extremely accurate calculation is not a guarantee of the correct operation of the engine. One of the windings is connected directly to the network, and the second is connected using a capacitor. In the geometric dimension, the windings in the stator are placed opposite each other. So, step by step, we figured out how to connect a three-phase asynchronous electric motor to a single-phase network and what you need to calculate and know for this.

Asynchronous or collector: how to distinguish

Two of them are stator structural elements connected in parallel. Based on the maximum current flowing through it, a magnetic starter belongs to one of seven standardized groups. In fact, the launcher only works for seconds. As a rule, the resistance of the windings will be no more than several tens of ohms.

For example, on the operating conditions of the engine itself, on the connection diagram, on the capacitors, or, more precisely, on their capacity. For this purpose, the circuit provides for the presence of a special button designed to open the contacts after the rotor reaches a given speed level. Another example when measurements can show 10 ohms, 10 ohms, 20 ohms.

When you need to quickly spin up the engine, a circuit with a starting capacitor is used. It makes no difference what kind of working winding you have and what kind of starting winding. For single-phase asynchronous AC motors with a running capacitor, the auxiliary winding is permanently connected through a capacitor. But in any case, losses will range from 30 to 50 percent.

The most common motors of this type can be divided into two groups: single-phase motors with a starting winding and motors with a running capacitor. She's in the second picture. Connect a three-phase motor to a single-phase network. Starting and running capacitors.

Disassembling the device: step-by-step instructions ↑

To repair a hood with your own hands, you need to know how to disassemble it. By following the instructions below, you should not have any serious difficulties with this process.

This instruction is an example of disassembling a modern kitchen hood. It is worth noting that in many models, individual blocks are mounted independently of each other. For example, to remove the engine, it is not necessary to unscrew the backlight unit.

Advice! If disassembly requires disconnecting connectors or wires, be sure to label or photograph the items before performing any manipulations. Thanks to this approach, you will not have any difficulties connecting blocks during assembly.

CONNECTING A COMPUTER FAN TO A 220 V NETWORK

In the process of resuscitation and modernization of Solntsev’s amplifier, we had to get rid of the bulky power supply made on the TS-180 transformer. A switching power supply based on IR2153 with a power of 200 W was manufactured. However, during operation, with a removed power of about 130 W, heating of the pulse transformer was detected. Not critical, but still present. In addition, the stabilizers L7815 and L7915 heated up quite noticeably. The tight mounting on the board did not allow installing large radiators.

To eliminate this effect I decided to use a cooler. The choice settled on a small-sized fan with a power of 0.96 W with a power supply of 12 volts and a current consumption of 0.08 A. Since a transformer power supply for it would have unacceptable weight and dimensions, I decided to assemble a transformerless power supply with a quenching capacitor.

Scheme

In general, a transformerless power supply is a symbiosis of a rectifier and a parametric stabilizer. Capacitor C1 for alternating current is a capacitive (reactive, i.e., not consuming energy) resistance Xc, the value of which is determined by the formula:

where f is the network frequency (50 Hz); C is the capacitance of capacitor C1, F. Then the output current of the source can be approximately determined as follows:

where Uc is the network voltage (220 V).

With a consumption current of 0.08 A, capacitance C1 should have a nominal value of 1.2 μF. Increasing it will allow you to connect a load with a large current consumption. Approximately, you can focus on 0.06 A for each microfarad of capacitance C1. I had 2.2 microfarads at 400 volts on hand.

Resistor R1 serves to discharge the capacitor after turning off the power supply. There are no special requirements for it. Nominal 330 kOhm - 1 Mohm. Power 0.5 – 2 W. In my case 620 kOhm 2 W.

Capacitor C2 serves to smooth out the ripples of the bridge-rectified voltage. Rating from 220 µF to 1000 µF with an operating voltage of at least 25 volts. I installed 470 uF at a voltage of 25 volts.

1N4007 from a used energy-saving lamp were used as rectifier diodes.

The zener diode (12 Volts) serves to stabilize the output voltage and by replacing it you can achieve almost any required voltage at the output of the power supply unit.

When assembling the circuit, you should keep in mind that the fan connection should be made correctly from the beginning. An error in soldering the fan wires in the wrong polarity will cause the fan to fail. And the connection itself (soldering) should be done in advance, since the no-load voltage at the fan connection points can be 50-100 volts. If the polarity is correct (the red wire is the positive power bus), then when connected to a 220 V network, the fan will have approximately +12 volts.

The printed circuit board is made using the LUT method. Etching was carried out with hydrogen peroxide, citric acid and table salt at the rate of 50 ml of peroxide, 2 tsp. acid and a teaspoon of salt.

In addition, I provide a diagram (maybe someone will need it) for adjusting the fan speed.

Essentially, this is a voltage regulator supplied to the fan motor. A change in voltage leads to a change in fan speed. A constant resistor R2 was specially introduced into the circuit, the purpose of which is to limit the minimum fan speed, so that even at the lowest speed, i.e. at the lowest voltage, ensure its reliable start.

Information selection

Remove the fan from the engine by releasing the spring clip or other fastener. First of all, the noise. In order to ensure air flow in the kitchen, either install a ventilation valve, which can be a wall or window, or make decorative perforations at the bottom of the kitchen door.

Why does the check valve sometimes not work and not close? A check valve is mounted on the tee on the kitchen side. Later, the appliance begins to heat up, which often leads to accelerated failure of the kitchen hood. We disconnect the panel with the lighting lamps, having first disconnected the power connectors. The first is its connection to electricity. Using buttons or a movable lever, the necessary contacts are switched, supplying voltage to the electric motor windings. A mixture of odors that are attractive at first turns over time into a mess of partially decomposed volatile organic matter, the presence of which in the air is unlikely to please anyone. When choosing a hood model, it is better to give preference to those devices whose anti-grease filters are equipped with an anti-corrosion coating. But electric motor malfunctions require major repairs and professional intervention. But this option is unlikely. Fan connection