Circuit Current Limiting

The short circuit basically consists of a connection without resistance, existing between conductors under voltage or in some cases can be considered as an intentional or accidental connection between two points of an electrical system or equipment, or of an element, through an impedance unsatisfactory. Fuses refer to components used for the purpose of performing their main function, which is to limit the current of a circuit, providing its interruption in case of short circuits or long overloads.

Its operation is based directly on the fusion of a component by the Joule effect, caused by the sudden rise of current in a specific circuit. The fuse component has physical properties such that its melting point is less than the melting point of copper, and it is the most sought after material used in conductors of different applications. Thus, by means of a transient resistance, the current may have a value greater than the operating current. Thus, the equipment GF1524BG and part of the installation may undergo a thermal stress, ie, a short-lived, or electrodynamic, suppressor current, which is an excessively high rated impulse current.

Fundamentals of Electrical Commands

It is extremely relevant to understand the follow-up of the electric controls, in which they represent techniques and methods used to control or manipulate drives of machines and equipment. These electrical controls consist largely of power circuits, in which it is possible to find the loads, as well as the control circuit, which reach the logic of activating switching and protection components.

The electrical commands consist of electrical and electronic processes in which, through the logic of contacts can activate electric machines and automation systems, residential or industrial. In this way, they consist of load drive circuits and industrial machines. The drive of loads is the process of triggering heating systems, large lighting and cooling, for example. In electric power applications, electric commands, when it comes to the industrial sector, need to be emphasized since they represent the largest part of the transformation of electric energy into other types of energy.

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The industry ends up being the place of the activities carried out by most of the professionals of the electric branch, be it in the form of electrical command projects, installation of accessories and equipment, or even of industrial automation projects.

 

Continuous and Alternating Current

Electric motors consist of machines capable of transforming electrical-type energy into mechanical energy. The electric motor considered the most used in the industries is the induction, since it has been able to combine the numerous advantages of the use of electric energy, low cost, easy transportation and handling, effective performance, simplicity of command with simple and large projection Versatility of adaptations to the most different types of loads. The types of electric motors found considered to be the most common are electric motors of direct current and alternating current.

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AC motors are the most used, taking into account that the distribution of electric energy is effected in alternating current. The main types of the same are the synchronous and induction motors. While DC motors are more expensive and need a direct current source, or a device that converts ordinary AC power to DC. They can operate at an adjustable speed with wide limits and flexible and precise controls. In this way, its use becomes restricted only to specific cases in which these requirements can compensate the high cost of the installation.

 

Tank with Oil Conservative

One of the first alternative methods of preserving oil was the tank with a preservative. In conservative transformers, the main reservoir is completely filled with oil, and a smaller reservoir with a small amount of oil, the conservative tank, is mounted above the main tank and connected by a tube called a gooseneck.

The conservator is ventilated by air, and during its normal operation, its oil level will be halved to allow expansion and contraction of the oil at the time of a critical operation.

The goal of the gooseneck is to prevent the contact of hot oil, generated by the core and the transformer coils with the conserved oil cooled. This result is partial, since there is always some contact between the two oils.

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The oil in the main tank of the transformer is under a slight positive pressure, equal to that of the conservator. In the conservator, a dehumidifier can be installed to keep the oil free of moisture, which works for time-fitted transformers.

The dehumidifier has to be replaced at regular intervals and the change from pink to blue will indicate when replacement needs to be made.

Factors Affecting the Life of Electric Motors

We have several factors to consider that affect the life of electric motors, such as thermal, mechanical, electrical, environmental and poor maintenance. These factors change the temperature of the engine relative to the ambient temperature, because of internal losses.

The storage of the engine is also very important and should be suitable for preserving the quality of the engine that is still in stock, unused.

There are many indications of adjustments for the enormous diversity of thermal models, because of the different factors that damage the temperature variation of an engine.

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To determine the final temperature of the electric motor, the simplified thermal model will be applied, where the motor is considered a homogeneous body, and the absorbed energy is evenly supplied to the environment. At the beginning, the driven motor will have a temperature increase until reaching the thermal equilibrium, it is when it will initiate the process of heat exchange with the environment.

When developing the conjugate to drive a mechanical load coupled to its axis, the electric motor will have an increase in temperature. This temperature must not exceed the value defined by the insulation class. To determine this elevation will require the development of a thermal model.

Magnetic Core and Stator Static Winding

The magnetic core is charged with raising the magnetic flux of the field caused by the coils and thereby forming electromagnets at its poles. In direct current electric motors, these poles are fixed, as in alternating current motors the field generated is the rotating field.

The stator is designed with several thin blades of magnetic material, pressed to construct the stator assembly. The magnetic materials of the motor cores must have high saturation induction, allowing the motor to work at a high magnetic flux point, always below the saturation point.

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The space designated for the coils is called a groove, and the structures that will constitute the poles themselves are the teeth. In the stator winding, copper coils are wound around the stator teeth, and these windings are three-phase or single-phase induction motors.

The coils are separated from each other through a varnish layer, insulated from the groove, fastened with an insulated string, and again covered with an additional layer of varnish. They are installed in such a way that the ligature of the three phases can be completed in star, triangle or other tensions.

Electric Motors and their Rotation

It is in RPM that the rotation of an electric motor is expressed, RPM – revolutions per minute represent the amount of turns in the motor shaft.

Each engine is specific to its task and has its own characteristics of power, shape and size. The speed of rotation of the electric motor is defined by two factors, the frequency of the AC source and the number of magnetic poles of the motor.

The frequency of the mains that the electric motor is connected directly influences the rotation of the motor. In the frequency of 50Hz the synchronous rotation will be 3,000 RPM and in the frequency of 60Hz with 2 poles the synchronous rotation is 3,600 RPM.

The essential feature for the operation of electric motors SealMaster CRSTF-PN22 in appliances is the rotation and this may seem obvious when we observe the operation of fans, blenders, blenders, but it appears disguised in the washing machines or electric windows of automobiles.

Rotating motion can cause the process to advance, swing or return as needed and it can rotate clockwise and counterclockwise as required.

Relays

In electric motors, relays are the essential components of electric charge manipulation, as they allow the combination of logic in the control, as well as the separation of power and command circuits.

The most common are made up of a housing with five terminals. The terminals (1,2) correspond to the excitation coil. The terminal (3) is the input, and the terminals (4,5) are equivalent to the normally closed (NF) and normally open (NO) contacts, respectively.

A fundamental peculiarity of the relays is that the voltage at the terminals (1,2) can be 5 Vdc, 12 Vdc or 24 Vdc, while simultaneously the terminals (3,4,5) can work with 110 Vac or 220 Vac.

That is, there is no physical contact between the drive terminals and the working terminals. This definition allowed the advent of two circuits in an electrical panel:

Control circuit: this is the interface with the operator of the machine or instrument and, in the meantime, operates with low currents (up to 10 A) and / or low voltages. NJ 406 MA/C3P

Power Circuit: this is the circuit where the loads to be connected are located, such as motors, heating resistors, among others. In this can circulate electric currents of the order of 10 A or more, and reach tensions of up to 760 V.

CONTROL OF ELECTRIC MOTORS – Stop and Direction of rotation

Shutdown – In certain applications there is a need to use a rapid motor and load deceleration. When disconnected from the power line, the electric motor uses a rotation reversing device with the motor still running. Stopping or shutting down the mains motor takes place through a relay preventing the motor from breaking in the opposite direction. In the case of synchronous electric motors, dynamic braking is used.

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Direction or Direction of Rotation – Most motors (except some, such as single-phase motors such as shaded pole and repulsion motors) can be used in both directions of rotation depending only on adequate control to achieve this . The direction of rotation of the axis of a DC motor is imposed by both the north-south polarity of the field flux and by the direction of the armature current. To reverse the direction of rotation, simply change the polarity of the DC source that feeds the field winding or DC source that feeds the armature, this in the case of independent excitation.

Universal Engine – Your Operation and Applications

Several home appliances, especially kitchen appliances, and various portable tools use another type of single-phase motor, called universal, whose operating principle is completely different from the induction motor.

The name of the universal electric motor comes from the fact that it can operate under both AC and DC power. In fact it is a DC series motor.

It is an electric motor of variable speed, with low speeds for large torque and high speeds for small loads.

The starting conjugate is also high and therefore is commonly used in small appliances, such as electric drills and sanders, requiring high torque, and in blenders, vacuum cleaners and centrifugal pumps, which require high speed.

They are usually manufactured for powers up to 3/4 HP. For powers above a few CV, these motors do not work very well in alternating current, therefore, a great friction occurs in the brushes what results in a decrease of the yield and the factor of power.

The stator is a set of protruding poles with coils wound on them and the rotor consists of a winding distributed in grooves and connected in series with the coils of the stator (armature). https://www.mrosupply.com/electrical/extension-cords-reels/cord-reels/2208276_lg3050-143-9_reelcraft/