Smooth Start Angle Grinder

How to make a speed controller with your own hands

In order not to complicate the perception of the principle of operation with complex terms, the principle operation of the circuit can be explained simply. It has a sensing element that reads the magnitude of the load. Depending on the read value, this element controls the shut-off device.

The principle of operation is similar to that of a water tap. In this case, you are the sensitive element that controls the water tap. The flow of water, depending on the need, becomes more or less. The same process occurs with the current.

It is necessary to correctly understand the moment that we will in no way be able to increase the rotation speed more than that indicated in the characteristics of the angle grinder. We can only lower the turnover. If the maximum rpm is 3000, then the range in which we can adjust the rpm will be below this value.

In its simplest form, you can use a thyristor-based regulator circuit. He will both feel and regulate. Two in one. This diagram has only five parts. It is very compact and fits easily into the case. Such a regulator will not work from zero rpm, but this is not necessary for an angle grinder.

If lower speeds are needed in the work, then it is necessary to use a different circuit on an integrated microcircuit, where a triac will be the locking element. Such a scheme will be able to regulate the speed from almost zero to the desired value.

And in that, and in the other scheme, the main load falls on the shut-off element. It must be rated for voltages up to 600 V and for currents up to 12 A. If your grinder is more powerful than 1 kW, then the locking element must withstand a load of up to 20 A.

Soft starter power tool

All the details of the circuit on the thyristor can be placed on a printed circuit board or simply surface-mounted. According to the second option, the parts are soldered onto a printed circuit board. The printed circuit board can be manufactured in different ways. It can be etched out of foil-clad PCB, you can even cut it with a cutter, but it will turn out very roughly. In principle, she can be asked to make a familiar radio amateur for a very modest remuneration.

When the finished board is ready, you need to choose a convenient place in the angle grinder case to install it. It is desirable to install it so that it is convenient to use, and so that it does not interfere with the work process.

Before installing the circuit in the car, you need to check it. To do this, instead of an angle grinder, an ordinary incandescent lamp must be connected to the output. A copy with a power of 60. 40 W at 220 V will do. The efficiency will be obvious by the change in the glow of the light bulb.

Now it remains to mount the device in the selected place and make a test run of the angle grinder. It will stop breaking out of your hands during start-up, and the speed will be smoothly adjusted by rotating the regulator.

If you have an old angle grinder among your tools, take your time to get rid of it. Using a simple wiring diagram, the tool can be improved by adding an option for adjusting the speed. Due to the usual control device, which you can create with your own hands within a few hours, the functions of the tool will significantly expand. By reducing the number of rotations per unit of time, the angle grinder can be used as a sharpening and grinding unit for different types of materials. There will be additional opportunities for using auxiliary equipment and attachments.

Connecting the regulator to the angle grinder

The frequency converter is connected to the instrument in series. If there is free space in the handle of the angle grinder, then this device can be placed there. The surface-mounted circuitry is glued with epoxy, which will serve as an insulator and vibration protection. Move the variable resistance resistor with a plastic handle outside to adjust the speed.

smooth, start, angle, grinder

What is the angle grinder for smooth start and speed controller?

In modern angle grinders, 2 necessary options are used that increase the characteristics and safety of the equipment:

  • speed regulator (frequency converter). a device designed to convert the speed of the motor in different modes of operation;
  • soft starter. a circuit that provides a leisurely increase in engine speed from zero to the limit value when the unit is connected.

They are used in electromechanical equipment, in the structure of which an AC electric motor with a collector is practiced. They help to reduce the wear of the mechanical part of the unit when it is turned on. Reduce the stress on the electrical components of the machine by bringing them into operation smoothly. As studies of the qualities of materials have revealed, a particularly strong development of contacting nodes is produced in the process of a sudden transition from a stationary state to rapid activity. For example, one start of an internal combustion engine in a car is equal to the wear of the piston and a group of sealing rings to 700 kilometers.

When power is applied, an abrupt transition is made from a stationary state to the rotation of a circle at a speed of 2.5-10 thousand revolutions in 60 seconds. Anyone who has used an angle grinder is well aware of the feeling that the tool “flies out of hand”. Just at this moment, most of the accidents associated with the mechanical part of the unit happen.

The rotor and stator windings are equally stressed. An alternating current electric motor with a collector starts up in a short-circuit mode, the EMF already pushes the shaft forward, but the inertia force still does not allow it to rotate. A jump in the starting electric current arises in the coils of the electric motor. Despite the fact that by design they are designed for such work, over time a moment comes (for example, with a voltage drop in the mains) when the winding insulator is not able to withstand and a short circuit occurs between the turns.

With the introduction into the electrical circuit of the instrumentation schemes for adapting a soft start and changing the frequency of rotation of the motor, all the above troubles spontaneously disappear. In addition, the issue of a sudden and significant decrease in voltage in the general power grid during the start-up of the tool is being resolved. Hence, it is clear that household electrical appliances will not be at risk of failure. And the automatic switches on the electric meter will not work and turn off the current in an apartment or house.

The soft start scheme is used in angle grinders of the middle and high price segment, the speed control unit is more and more in professional modifications of the angle grinder. Adjusting the speed makes it possible to process soft materials with an angle grinder, to carry out delicate grinding and polishing, since at high speeds the wood or paint will simply burn out. Auxiliary electrical circuit increases the cost of the toolkit, but extends the service life and the degree of safety in use.

Installation of the regulator in the cavity of the angle grinder housing

The electronic device, assembled separately from the angle grinder, is encased in a dielectric material since all components are energized. A portable electrical outlet with a cable is fixed to the body. The handle of the variable resistance resistor is brought out to the outside. The regulator is connected to the mains, and the tool to a portable power outlet.

How to assemble a regulator with your own hands?

A simplified and rather reliable frequency converter for an angle grinder is constructed with your own hands from available electrical parts. Below is a diagram that shows all the required components for mounting on a printed circuit board of the device of interest to us.

So, we need:

  • symmetrical triode thyristor (or triac, triac) DIAC (DB3);
  • resistor (resistance) R1 (its parameters should be 4.7 kΩ);
  • additional triac VT136 / 138 (TRIAC);
  • capacitor C1 (400 V, 0.1 μF);
  • additional resistance VR1 for 500 kOhm.

A similar scheme operates according to the following method.

  • The charging time of the capacitor is modified by an auxiliary resistor (it is called the trimmer). When voltage is applied to the circuit, the triacs are in the closed position, and a zero voltage value is observed at the output.
  • In the process of charging the capacitor, an increase in voltage is noted on it, which leads to the opening of the DB3 triac. As a result, the voltage falls on VT136 / 138. This thyristor element also opens up, and an electric current flows through it.
  • After that, the symmetrical components are closed again and remain in a similar status until the capacitor is completely recharged in the opposite direction.
  • Ultimately, at the conclusion, we acquire a deterministic signal of finite energy that is complex in its configuration. Its exact range is determined by the period of performance of the functions of the circuit capacitor. auxiliary resistance. resistance R1.
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Triacs are usually located on a printed circuit board. It is easy to create it from PCB (multilayer extruded plastic is used, consisting of heat-insulating fiber and foil). Individual craftsmen cut the board with a cutter. It is practiced to place the circuit elements using the hinged mounting method. Triystres are mounted only on an aluminum or copper heat exchanger. It plays the role of a good heat sink.

The test of the assembled device is carried out using an ordinary 40-60 W incandescent lamp. Connect it to the circuit and start to regulate the glow power. If the brightness changes, then you have done everything correctly. Now you can start installing the regulator in the shell of the angle grinder. This is not very easy to do, since it is necessary to ensure that the auxiliary device does not interfere with you when using the angle grinder.

You will need to calculate the installation location of the homemade control device yourself, in accordance with the design features of the angle grinder. Installation of the scheme is performed:

The circuit itself is connected to the device by integrating it into the electric power supply channel of the angle grinder. With this, you, I suppose, will not have difficulties.

Soft-start controller for angle grinder

Due to the design features, the start of the angle grinder is associated with high dynamic loads. Due to the mass of the working disk, at the beginning of rotation, inertial forces act on the gearbox axis. This entails some negative points:

    Axle loads during a sharp start create an inertial jerk, which, with a large diameter and mass of the disc, can pull the power tool out of the hands;

As a result, the brushes wear out and both windings of the electric motor overheat. With the constant turning on and off of the power tool, overheating can melt the insulation of the windings and lead to a short circuit, with subsequent costly repairs.

High torque with a sharp set of revolutions prematurely wears out the gears of the reducer. Angle grinder;

In some cases, teeth may break off and the gearbox will jam.

Overloading the working disc can destroy it when starting the engine.

Therefore, the presence of a protective casing is mandatory.

To better understand the mechanics of work, consider the device of the angle grinder in the drawing. All elements experiencing overload during a sharp start are clearly visible.

Schematic drawing of the arrangement of working bodies and control systems in an angle grinder

To reduce the harmful effects of a sudden start, manufacturers produce an angle grinder with speed control and smooth start.

The speed control is located on the tool handle

But only models of the middle and high price category are equipped with such a device. Many home craftsmen purchase an angle grinder without a regulator and slowing down the starting speed. This is especially true for powerful specimens with a cutting disc diameter of more than 200 mm. Such an angle grinder is not only difficult to hold in your hands during start-up, but mechanical and electrical wear occurs much faster.
There is only one way out. to install the smooth start of the angle grinder yourself. There are ready-made factory devices with a speed governor and a deceleration of the engine start at startup.

Finished soft start control device

Such blocks are installed inside the case, if there is free space. However, most users of an angle grinder prefer to make a circuit for a smooth start of an angle grinder on their own, and connect it to the break in the supply cable.

Electronic device testing

Before connecting the block to the angle grinder, check it. Take a plug-in electrical outlet. Insert 2 wires into it, one of which connect to the board, and the other to the network cable. Connect another wire to the network board. As you can see, the regulator is connected in series in the electrical circuit. Connect a light bulb to the circuit and test the operation of the device.

smooth, start, angle, grinder

How to connect?

If you need to connect the soft start function to the angle grinder with your own hands, then you need to do this through an adapter. The input pins of the conductor must be connected to the rectifier unit. The correct definition of the zero phase plays an important role in this. The contacts of the device are fixed with a blowtorch. In order to check the performance of the device, you must use a special tester.

Among other things, the speed controller of the grinder can be placed directly in the socket. The tool will work from it. The connection requires a junction box, a socket and a regular mains cable. A hole must be made in the junction box (can be drilled) to accommodate the AC regulator. The board is placed inside the box, and the socket is attached to it. This regulator is applicable not only to the grinder, but also to any device that will be connected to this outlet.

It is important to remember that these jobs involve high voltages. Therefore, it is imperative to observe safety precautions in order to avoid accidents.

So, it was considered above for what purposes in the angle grinders there is a soft start function and a cutting wheel speed controller. Usually, these functions are already built into modern tools, but if they are absent, if you really want to, you can install them and connect them yourself.

How to make a smooth start for an angle grinder, see the video below.

A very handy feature, especially in large instruments. The fact is that an angle grinder without a soft start turns on abruptly and sometimes it happens that being in an uncomfortable position, you can not hold the tool. In addition, you can injure yourself or damage the material being processed.

This function is most often found on angle grinders with a disc diameter of 180 and 230 mm.

Pros of soft start:

With a soft start, you can avoid sudden jolts of the tool.
Electricity flows smoothly into the tool, which prolongs the life of the angle grinder.
Work comfort.

Features and purpose

What is the soft start function for? The reason is that when the angle grinder is turned on, a large voltage is suddenly applied to its motor. This has an extremely negative effect on the electronics of the instrument, and also wears out the wiring. It is the sudden power surges that most often disable the angle grinder. In addition, with a sharp start, it is quite difficult to hold the instrument in your hands, because it begins to shake and lead to the side. All this can lead not only to breakage of the instrument, but also to injury. That is why most manufacturers have equipped their models with a soft start function and speed control.

The speed control function is useful in that such an angle grinder can perform various types of work. The speed of rotation of the disc is selected depending on what you need to do the angle grinder. grind, polish or cut the material. The speed of rotation of the discs can affect the quality of the surface cut. For example, hard surfaces require a high rotation speed of the disc, while softer surfaces require a low speed. Grinding work is very difficult without a wheel speed controller.

It is imperative to keep safety in mind when working with an angle grinder. This is a traumatic device, so negligence in handling it is unacceptable. It is necessary to work in a protective mask, gloves and hold the sander firmly with both hands so that it does not slip off the treated surface.

What is soft start

A smooth start-up of an angle grinder is an increasing voltage supply to its motor, at which it accelerates without starting current surges and with a gradual increase in torque. This mode protects the supply network from excessive power take-off and prevents it from “sagging”. This is especially true when the angle grinder is powered from autonomous voltage sources. In addition, it protects the motor windings from over-rated currents that can lead to their breakdown. With a soft start, the gearbox of the angle grinder does not experience shock loads, which protects it from premature wear.

The electronic circuitry for smooth start-up of the angle grinder is based on the same principle as the speed controller circuit. It also uses a triac to limit the supply of power to the electric motor. But unlike the speed controller, the control pulses to the triac are not formed by manually setting the resistance in the RC circuit, but by an electronic circuit that forms a sequence of pulses with a decreasing delay duration. The diagram below shows how the pulse shift time is shortened and the power supplied to the motor of the angle grinder increases.

Since the soft start and the speed controller work on the same circuitry, electronic units are produced that combine the functions of both of these devices.

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Selection Tips

How to choose the right angle grinder? To do this, it is worth using several basic criteria.

To choose the right tool, it is worth deciding on the specific type of work to be performed with this tool. angle grinder can be of different types: mains, with batteries, gasoline and pneumatic.

Network models are perhaps the most common. Such an angle grinder works from a home network, that is, from a simple outlet. Such models of the tool have high power, compactness and high rotational speed of the cutting discs.

But the limitation in working with such an angle grinder is due to the dependence on the mains. For example, when working on the street, there is not always a power outlet nearby and you have to use various extension cords.

Cordless devices are deprived of this disadvantage. They have a special mount for power supplies that are charged from the mains. After charging, you can work with such a tool without any wires. Typically, such an angle grinder has a compact size and small diameters of the cutting discs. As a rule, such models are more expensive than standard tools. Also, the period of their operation is limited by the capacity of the power supply.

Gasoline angle grinders are not common. Such devices are large in size, because they need a fuel tank, as well as an internal combustion engine. Among the advantages, it is worth highlighting the high power of these models, a wide range of choice of disks and autonomy. The negative aspects include their weight and volume, high noise level and, of course, additional fuel costs for the operation of the device.

Pneumatic models of an angle grinder are often used for industrial purposes and very rarely for household work. This is an unusual angle grinder that runs on compressed air and needs a special compressor. For such models, the problem of overheating is completely eliminated, and the period of operation can be limited only by the human factor. Also, such models are the lightest and quietest.

For simple work on the processing and grinding of surfaces, light models of grinders with a small diameter of the cutting wheel are suitable. For work on cutting durable materials, it is worth choosing more powerful and, accordingly, bulky equipment with a large disc diameter. The diameters of the discs can be from 125 (minimum size) to 230 (maximum size) mm. that is, the range of sizes is quite wide. The universal cutting disc diameter is 180 mm. Such a circle can both process surfaces and cut material.

When choosing a disc, it is worth conducting a careful visual inspection. Even minor damage and chips can lead to extremely sad consequences. By the way, almost 90% of accidents when working with an angle grinder are caused by a defect on the cutting discs.

Convenience of work is also an important selection criterion. The angle grinder should be equipped with comfortable handles, should not slip out of the palm and be heavy. Many angle grinders have an electronic relay to protect against power surges and overloads. This is a useful feature, so it is worth choosing a tool with such a fuse.

It is recommended to select models with a soft start function. This will help the tool last much longer, and it is much more convenient and safer to use an angle grinder with this function.

Diagram of a smooth start angle grinder with your own hands

Almost all models of the angle grinder of the lower price range do not have such useful options as spindle speed adjustment and soft start. If you have a desire and some skills, you can make a speed controller for an angle grinder with your own hands, although it is much easier to purchase a ready-made electronic unit for several hundred rubles. The speed control expands the capabilities of the angle grinder and allows it to machine soft materials at reduced cutting speeds. In addition to the speed controller for an angle grinder, a very useful function is a soft start, which smooths out a sharp increase in the current in the windings of the electric motor at the moment the voltage is applied to it. This prevents an abrupt increase in torque and “sagging” of the supply network. In addition, the smooth start-up reduces shock loads on the motor and gearbox of the angle grinder, which protects them from premature wear.

Why do you need to adjust the speed of the angle grinder

Any angle grinder is structurally “sharpened” to work only with a cut-off or grinding wheel of a certain diameter. In total, there are six most common diameters in the range from 115 to 300 mm, which correspond to six groups of spindle speeds at idle speed. For example, an angle grinder with Ø125 mm wheels has a rotational speed of about 11 ÷ 12 thousand rpm, and with wheels Ø150 mm. 9 ÷ 10 thousand rpm. Such values ​​of the spindle speed are due to the fact that cutting discs are designed for high-performance processing of hard materials (metal, stone, ceramics) at cutting speeds up to 80 m / s.

However, when cutting and especially grinding soft and tough materials, completely different cutting parameters are required and, accordingly, the use of a tool with a speed controller. And this applies not only to wood and plastics, but also to steels, titanium and aluminum alloys. For example, processing of plastics and soft types of wood occurs at cutting speeds from 8 to 12 m / s, grinding of titanium and stainless steel alloys. within 15 ÷ 20 m / s, and even ordinary steel is polished at no more than 30 m / s. Therefore, the rotation speed of the grinding attachments for an angle grinder should be several times less than the passport one. It should be noted that in the bulk of the angle grinder speed controllers are in essence power controllers supplied to the angle grinder electric motor. That is, a decrease in the number of revolutions is achieved by reducing the power of the source by up to 15% of the nominal. But for grinding and cutting soft materials, this does not really matter, since in this case, a little power is initially required.

Soft starter

On modern grinders, the soft start function is already installed, but some craftsmen independently supply their angle grinder with a soft start device. In principle, it is not so difficult to put a limiter.

You can purchase ready-made devices for soft start, or you can make such a device yourself. Below is one of the most famous schemes of the soft starter of the tool.

So, for the manufacture of a soft start system you will need:

  • microcircuit. KR1182PM1;
  • R1. 470 Ohm R2. 68;
  • C1 and C2. 1 microfarad. 10 volts;
  • C3. 47 microfarads. 10 volts.

The essence of the work of such a device is the following characteristics.

  • When the device is turned on, the voltage from the network begins to flow to the microcircuit (DA1).
  • Then the control capacitor starts to charge gradually. After that, the device reaches the desired voltage indicator. For this reason, the thyristors open in the microcircuit with a slight delay. The period of this delay depends on the time it takes for the capacitor to fully charge.
  • Triac VS1 will also open gradually. This is because it is also controlled by thyristors.

These processes are carried out in periods that gradually become smaller. And for this reason, the voltage that is applied to the angle grinder motor does not rise in leaps and bounds, but gradually. This allows the angle grinder to switch on smoothly.

The capacity of the capacitor C2 directly affects the time it takes for the motor to fully start to work. The capacitor, which has a capacity of 47 μF, starts the device in about 2-3 seconds. And at the moment when the angle grinder is turned off, the capacitor C1 is discharged using a 60 kΩ resistor R1. This happens in about the same time as turning on. Then the tool can be run again for further work.

This unit can be easily connected to any device that is designed for a voltage of 220 V. The basis of this device is a microcircuit and a triac. The main thing is that the minimum current of the triac is 25 A, and its maximum voltage is 400 V. Such a circuit is assembled on a printed circuit board. The board should be wired as compactly as possible.

Ways of connecting the regulator inside the housing Angle grinder

There is more than enough space in the grip part (rear handle) of the angle grinder to install a regulator with such dimensions. In low-power angle grinders, the free space is usually located closer to its end, and in more powerful ones. between the handle and the motor or in the handle itself (see photo below). No special skills are required to install such a regulator, since it just needs to be included in the open circuit of the electric motor power supply.

The video below shows the resuscitation of an old angle grinder equipped with a speed controller. Interesting push-button control of the number of revolutions with memorization of the value after turning off the supply voltage.

Diagram of the smooth start of the electric motor do-it-yourself angle grinder

Everyone who uses an angle grinder for more than one year, it broke. At first, each craftsman tried to repair the sparkling grinder on his own, hoping that it would work after replacing the brushes. Usually, after such an attempt, the broken tool remains on the shelf with burned-out windings. And a new angle grinder is bought to replace.

smooth, start, angle, grinder

Drills, screwdrivers, rotary hammers, milling cutters are necessarily equipped with a speed controller. Some so-called calibration grinders also have a regulator, while conventional angle grinders only have a power button.

See also  How To Grind An Angle Grinder Metal

Manufacturers do not deliberately complicate low-power angle grinders with additional circuits, because such a power tool should be cheap. It is clear, of course, that the service life of an inexpensive tool is always shorter than that of a more expensive professional.

The simplest angle grinder can be upgraded so that the gearbox and armature winding wires are no longer damaged. These troubles mainly occur with a sharp, in other words, shock start of the angle grinder.

All modernization consists in just assembling the electronic circuit and fixing it in the box. Separate box because there is very little space in the sander handle.

A proven, working diagram is laid out below. It was originally intended to adjust the incandescence of lamps, that is, to work on an active load. Its main advantage? simplicity.

  • The highlight of the soft starter, the schematic diagram of which you see, is the K1182PM1R microcircuit. This microcircuit is highly specialized, of domestic production.
  • The acceleration time can be increased by choosing a larger capacitor C3. While charging this capacitor, the electric motor picks up speed to the maximum.
  • There is no need to replace the resistor R1 with a variable resistance. The 68 kΩ resistor is optimally matched to this circuit. With this setting, you can smoothly start an angle grinder with a power of 600 to 1500 W.
  • If you are going to assemble a power regulator, then you need to replace the resistor R1 with a variable resistance. A resistance of 100 kΩ or more does not lower the output voltage. By short-circuiting the legs of the microcircuit, you can completely turn off the connected angle grinder.
  • By inserting a semiconductor VS1 of the TC-122-25 type, that is, at 25A, into the power circuit, you can smoothly start almost any commercially available grinder with a power from 600 to 2700 W. And there is a large margin of power in case the grinder is jammed. To connect an angle grinder with a power of up to 1500 W, the imported semiconductors BT139, BT140 are sufficient. These less powerful electronic keys are cheaper.

How to Use an Angle Grinder

The semiconductor in the above circuit does not open completely, it cuts off about 15V of the mains voltage. This voltage drop does not affect the operation of the angle grinder in any way. But when the semicistor heats up, the revolutions of the connected instrument are greatly reduced. This problem is solved by installing a radiator.

This simple circuit has one more drawback. its incompatibility with the speed control installed in the instrument.

A socket is screwed to the box and a cable with a plug is connected, which makes this design outwardly similar to an extension cord.

If experience allows and there is a desire, you can assemble a more complex soft start circuit. The schematic diagram below is standard for the XS – 12 module. This module is installed in the power tool at the factory.

If you need to change the speed of the connected electric motor, then the circuit becomes more complicated: a trimmer is installed at 100 kOhm, and an adjusting resistor at 50 kOhm. Or you can simply and roughly introduce a 470 kOhm variable between the 47 kOhm resistor and the diode.

In parallel with the capacitor C2, it is desirable to connect a 1 MΩ resistor (it is not shown in the diagram below).

The supply voltage of the LM358 microcircuit is in the range from 5 to 35V. The voltage in the power supply circuit does not exceed 25V. Therefore, you can do without an additional Zener diode DZ.

Whichever softstarter you build, never run a connected tool under load. Any soft start can be burned if in a hurry. Wait for the angle grinder to unwind and then work.

Characteristics of soft start and braking devices (SCP)

In transient modes (start and stop) of electric drives with an asynchronous motor, the instantaneous current can exceed the rated one by 5–8 times. This puts stress on the internal power supply, which can lead to short circuits, overheating and premature wear of the starter windings. The rotor torque increases by 1.5–2 times, causing dynamic shocks and accelerating the wear of the mechanical elements of the engine. There is a load on the drive-powered system. For example, in pumping systems, water shocks are observed, in conveyors. gusts of the conveyor belt.

A means of circumventing these troubles is a soft starter. an electromechanical or electronic device for regulating the processes of acceleration and deceleration. When the engine is turned on, it ramps up the voltage supplied to the engine. from 30-60% of the nominal to full. It allows you to keep the upper limit of the starting current only 3-5 times higher than the rated one. Reduces electrodynamic loads and shortens start and stop times.

DeWalt DW745 soft start module install

Soft starters and brakes

  • Manufacturer: IHT (Ukraine)
  • Rated current, A: 16
  • Engine power, kW: 3.5
  • Mains voltage, V: 200-240

Out of production

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 6.8
  • Engine power, kW: 3

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 6.8
  • Engine power, kW: 3

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 9
  • Engine power, kW: 4

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 16
  • Engine power, kW: 7.5

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 12
  • Engine power, kW: 5.5

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 25
  • Engine power, kW: 11

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 30
  • Engine power, kW: 15

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 37
  • Engine power, kW: 18.5

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 45
  • Engine power, kW: 22

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 60
  • Engine power, kW: 30
smooth, start, angle, grinder

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 105
  • Engine power, kW: 55

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 106
  • Engine power, kW: 55

in stock

  • Manufacturer: ABB (Switzerland)
  • Rated current, A: 143
  • Engine power, kW: 75

in stock

If you have any difficulties in choosing, please contact:

The considered devices are used in drive systems:

  • with reversible gear, belt and chain drives;
  • with high inertia: presses, crushers, mills, centrifuges;
  • conveyor and conveyor lines;
  • compressors;
  • pumps and pumps (including compensation for excess pressure);
  • fans.

The operation of “soft” starters is based on power thyristors (triacs) connected in opposite directions. The variability of devices is due to differences in the methods of changing the voltage depending on the load on the motor, in the control circuits, in the service functions.

Regulation schemes are due to the inclusion of the soft starter in the supply network:

  • single-phase. only to mitigate mechanical stress shocks, smooth braking and starting current limitation are not carried out; used with motors up to 11 kW;
  • two-phase. for light starting modes of a drive with a power of up to 250 kW;
  • three-phase. universal starters suitable for frequent starts and stops (typically up to 30 times per hour for 10 s) and provide accurate retention of user characteristics.

The soft starters perform amplitude or phase voltage control. Amplitude control is acceptable for starting in idle or lightly loaded conditions. Phase. optimal for drives with “heavy” and frequent starts.

Additional service functions expand the scope of the starters:

  • Torque control is important for the steady speed of systems such as translational motion and to prevent wear. The design includes a control loop that calculates the values ​​of the moment on the shaft and maintains the set value by changing the voltage.
  • Mechanical overload protection.
  • Thermal protection.
  • Phase break or imbalance alarm.
  • Pseudo-frequency regulation. reducing the motor speed for a certain time to debug the system.
  • Dynamic braking by applying a constant voltage to the EM winding; it is used for systems with resistive load, moving in the absence of a brake, i.e. for prestart stop.
  • Jogging (BOOST functions) for mechanisms with high inertial mass.
  • The bypass (bypass contactor) turns off the soft starter to minimize energy losses and protect the thyristor controller from overheating. Triggered in steady state engine operation.
  • Reducing the supply voltage at low load. used for pumping and ventilation systems in order to reduce energy consumption.

The task of the parameters of the soft starter. the time of starting and braking, the initial voltage. is carried out manually. External control of the starters can be analog or digital. Analog models are controlled by potentiometers and additional external devices. Digital ones are implemented by means of microprocessor controllers and have wide functionality. Configuration in such starters is performed from an interactive panel or via a network protocol of an industrial system.

The choice of soft starters is based on their overload capacity, requirements for starting and full motor current, the number of starts per hour. The soft starter current must exceed the rated motor current.

The soft starter does not regulate the EM speed in the operating mode and does not reverse the rotor. The soft starter will not provide protection against short circuit either. it is necessary to use the appropriate input automatic devices.