Association of normally open and closed contacts

There are basically two types, the association in series and the association in parallel (2.6b). When dealing with a contact association, it is normal to set up a table containing all possible combinations of contacts. It is known as Truth Table.

It is possible to notice that in the combination in series the load will only be activated only when these two contacts are activated, thus being called function E. In the combination in parallel any one of the connected contacts connects the load and for this reason it is called the OR function.

In the case of association of normally closed contacts, the NF contacts in the same way can be found in series and parallel. In the same way, the parallel association is called a non-E function. Just as to change a wheel in an automobile, when the tire sticks, it is necessary to know the tools themselves, their electrical commands, to really understand the operation of a circuit and later To draw the same, you need to know the appropriate elements.

The big difference is in the fact that in large panels there are high capacity buses that can subject people to risk situations. https://www.mrosupply.com/motors/ac-motors/commercial-motors/26949_chc244a_baldor/

 

Flux control

In order to obtain high performance, in the overload torque and in the transient regime, the inverters of this type carry out a flow control with the following functions: – estimation of the electric motor load made by measuring the current in the continuous stage of the inverter , – estimation of stator resistance.

This is the purpose of the engine gauge, known for the adjustment of the thermal protection and its thermal state. These two estimates allow calculating the voltage to be employed in the motor, at a given speed, to achieve the improved flow, – frequency gain. Prevents engine disconnection by preserving its constant torque. This is achieved by lowering the voltage and frequency, – over transient power.

An early rise in voltage is supplied to the motor SealMaster PN-32T during rapid decelerations, in order to keep the flow in a transient regime. This function is sometimes called “kinematic boost”, – slip compensation. In order to preserve the substantially constant rotational speed, the motor is fed at a slightly higher fret rate than on empty. This frequency rise is a function of the estimated load described above and the rated slip frequency of the motor.

Synchronous and asynchronous speed

Synchronous speed is the speed of the rotating magnetic field internally formed in the electric motor. Through it one can know the value of the motor rotation.

Slightly lower than the synchronous speed, the asynchronous speed is the rotation

Measured on the motor shaft. In summary, it is the true rotation of the engine, discounting the losses; Hence the name of asynchronous motor (in Portuguese asynchronous means out of sync, in the case between the speed of the magnetic field is the speed of the motor axis). The value read on the motor nameplate, so the nominal value is the value of the asynchronous speed.

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Slippage is the difference between the speed of the magnetic field (synchronous speed) and the rotation of the motor, also called slip. The slipping of an engine normally varies depending on the load: when the load is zero (no-load motor) the slip will be practically zero; When it is the nominal, the slip will also be the nominal.

Slipping can be given in rpm or%. Another feature that we must take into account is that slippage decreases as the nominal power of the electric motor increases.

Important Features for Properly Specified DC Motor

When selecting a DC electric motor, it is critical to identify the key performance specifications, as well as power and size requirements.

A DC motor is an electric motor that is powered by direct current (AC), and this power can come from a battery or any other DC power. Its switching (energy exchange between rotor and stator) can be through brushes (brushless) or brushless.

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In a DC motor, the speed can be controlled only by varying its voltage, unlike an alternating current (AC) electric motor whose speed is varied by frequency. Axle speed specifications generally refer to the unloaded speed, which is the maximum speed the motor can reach when there is no torque applied. Shaft speed is given in revolutions or revolutions per minute (RPM). It should not be forgotten that as speed depends on voltage and power supply, if a proper specification of the DC motor is not made, it may be a limiting factor.

The torque constant is also of paramount importance. The torque of an electric DC motor is proportional to the induction current, in which case we have the torque constant.

How Electric Motors Work in an Automobile?

Electric motors are basically made up of a set of parts mounted on a metal housing.

An important part of an electric motor is the field coil, which is attached to the housing inside the motor. This coil can be a magnet or an electromagnet. Powered by electric current, the field coil generates a magnetic field around the winding. If we have a natural magnet this field will exist around the induced. Another important piece is the armature, which is the central axis of the engine.

Through graphite brushes that slide into the armature collector there is a current flowing through the armature winding, which creates another magnetic field. The fields of the field coil and the armature combine, attracting and repelling, then, supported in bearings, the armature begins to rotate.

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Electric motors work this way and can be applied to various devices in the car. One of the ends of the armature may either contain a gear for locking a lock, such as containing a pulley or a coupling for engaging the combustion engine, and having a propeller for an internal fan or rotating a mechanism for cleaning the glass for breeze.

Implantation of electric motor

Before you buy an electric motor it is important that you know what model will fit your needs. That’s because in the market there are many different options and we need to know which one is indicated for what you need. In the market we can find models of electric motors in the three-phase segment and also single-phase, the implementation of each engine undergoes changes.

The electric motor deployment is done by professionals who are specialized in the field. These professionals do the installation of the engine which is a simple procedure but that requires attention and some details. It is very important to make this process available to a company that really understands it. here for more skf bearing

The electric motor has the function of transforming electrical energy into mechanical energy. This transformation is made on the basis of the principles of electromagnetism. The economy and efficiency are two very important factors for the engine to continue serving several segments.

How does a DC motor work?

The electric motor of direct current works based on the principle of reaction of a conductor that is placed in a fixed magnetic field and that is covered by an electric current.

The interaction that occurs between the fixed magnetic field and the magnetic field that is produced by the current that surrounds the conductor is responsible for the occurrence of a force that will circulate in the conductor of the electric motor. This force will drive the conductor out of the fixed magnetic field and thus the motion will be produced.

The electric motor skf qj 308 ma of direct current also has a magnetic field that is formed by the field coils. There are conductors that are installed in this field, in the rotor, and that are driven by electric currents.

The current flowing through the rotor loop of the electric motor moves in two directions, because to one side, the current enters and by the other, it leaves. This causes the formation of two opposing forces, but of equal value, and the result of this will be a conjugate rotation, since the loop is attached to the armature or to the rotor and suspended by a bearing.

Problems that the electric motor may suffer

Electric motor may suffer from: low insulation resistance or bearing heating / motor overheating

The electric motor can present many problems and these problems appear in the most diverse parts of the electric motor in a common way, because it is a machine that is operating in an interrupted way.

When the electric motor exhibits low insulation resistance changes, it means that the electric motor may be with damaged groove insulation; The cabins may be cut; The bobbin head may be contacting the casing; There may be presence of moisture or chemical agents or even presence of dust on the winding.

Overheating of the electric motor or heating of the bearings may occur due to: excessive axial or radial stress of the belt; Bent shaft; Loose or decentralized covers; Lack or excess grease; Foreign matter in the grease; Obstructed ventilation or have a smaller fan; The voltage or frequency may be out of specification; The rotor is crawling or failing; The stator is without impregnation; The overload; The bearing defective; Consecutive games; Air gap below specified; The capacitor remains unsuitable or improperly connected. https://www.mrosupply.com/hydraulics-and-pneumatics/hose-reels/2516639_ez-sh-550_coxreels/

Electric motor of alternating current has as principle of operation the magnetic flux

The alternating current electric motor has as its principle the magnetic flux both in time and space (sinusoidal), so as to produce a force in the air gap and this causes the rotor to rotate with defined torque.

By analyzing the loss equations, it is necessary to verify that there are ways to reduce the magnetic losses in the electric motor and this can decrease both losses through hysteresis and dynamic losses.

The reduction of this hysteresis loss in the electric motor involves metallurgy and materials, but there are processes in the production of electric machines that have a direct influence on the loss as the stamping of the blades, the heat treatment, the pressure exerted on the blades and many others.

When losses in the electric motor skf 61905 2rz are called dynamic losses, you can reduce reducing the thickness of the blade or even increasing the electrical resistance of the electric motor by incorporating silicon into the steel. When all these factors are optimized, all that remains is to improve all the details that are considered constructive in the electric motor.