Electric motors are machines that transform electrical energy into mechanical energy, and when we connect an engine to the grid, it will absorb a certain amount of electrical energy, and in turn drives a load, for example a tram. AC electric motors operate when connected to AC mains, are single-phase or three-phase if single-phase voltage or three-phase voltage are required. DC motors 108014.00 dc motors operate when connected to a DC voltage network. AC motors are currently the most commonly used; we can find them in domestic refrigerators. in machine tools etc. DC motors are of more restricted use, being found in electric traction, large rolling mills etc.
This process of converting the form of energy is equivalent to that which happens in a gasoline engine. In this engine, also called the explosion engine, it takes advantage of the energy coming from the burning of fuel to move the vehicle. In an electric motor the fuel is the electric energy. Engines are generally composed of two parts: the rotor which is the moving part and the stator or casing which is the fixed part and are classified as alternating and direct current motors.
Lubrication of bearings is normally done with mineral grease. When operating temperatures are high, from 120ºC to 150ºC or the speeds of rotation are above 1,500 RPM, we use mineral oil for lubrication. These oils must have the lubricating characteristics appropriate to the working conditions.
On low-power electric motors, initial lubrication is planned to ensure a large number of hours of operation. Sometimes the grease dodge 011297 reserve is sufficient for the entire life of the machine. On larger electric motors there is a need for external lubrication. The frequency of lubrication will depend on the design of the bearings and the characteristics of the lubricants used.
It is important to know that at a temperature of 40 ° C, the life of a continuously running ball bearing can be from 3 to 4 years or more. However, for every 10 ° C increase in working temperature the service life decreases by an average of 50%. Correct lubrication of the bearings, besides allowing an improvement of performance, avoids the increase of the temperature that damages the useful life of these equipments.
Servomotors may be classified as direct current servomotors and alternating current servomotors. It is also called the motor for control because servomotor is an electric motor primarily designed and built for use in feedback control systems. These motors have a high dynamic response, requiring little inertia of the rotor. They have smaller diameter and longer length and are designed to work allied to a servo-converter that follows a true reference to torque, speed or position.
The specialties of a servomotor are smooth rotation, high dynamic, low noise and vibration, the motor output torque proportional to the voltage applied and the direction of the torque determined by the instantaneous polarity of the control voltage. TIMKEN 471341 The most widely used type of servomotor is the one that uses alternating power supply. In them the rotor uses permanent magnets, the housing is made of aluminum and the stator is formed by a packet of blades and a sensor (resolver – analog or resolver – digital) is responsible for providing feedback signals to the servo inverter. Thus the converter is able to precisely actuate the servomotor. An alternating signal according to Faraday’s induction law allows the speed and position of the rotor shaft to be obtained.
Electric drive is the system capable of converting electrical energy into mechanical energy (movement), keeping this conversion process under control. It is used to access machines or equipment that require some type of controlled movement, such as the speed of rotation of a pump. The most widely used motors in the drives are single-phase and three-phase induction motors. Nowadays, the development of alternating current motor drive techniques and economic viability have favored the replacement of DC motors with induction motors driven by frequency inverters. In addition, due to its features and advantages, the DC motor is still the best option for applications in large and heavy machinery. 112-3-100
A modern electric drive normally consists of the combination of elements: Motor that converts electrical energy into mechanical; Electronic device that controls and / or controls electrical power; Mechanical transmission that adapts the speed and inertia between engine and load.
The choice of the engine and its stop and start devices, even if influenced by environmental aspects, is directly related to the mechanical load to be applied and to its impact on the electrical system. Resistant and dragging conjugates need to be analyzed to avoid operational problems such as wear, vibration, heating, etc.
When the electric drive of a motor does not determine a variation of the speed of the motor, requiring only a smoother start, in order to limit the starting current, avoiding power supply voltage drops, a great option consists of the use of soft-starters . Soft-starters are static starters designed to accelerate, decelerate and protect three-phase induction motors by controlling the voltage applied to the motor. Its use is common in centrifugal pumps, fans and motors of high power, whose application does not require the variation of speed.
These electronic devices are made of thyristor bridges (SCR or TRIAC) driven by a microcontroller electronic board. Thyristors are electronic components notably developed to work on alternating current. When SCR (silicon controlled rectifiers) are used, they are used in the antiparallel configuration, ensuring current flow in both directions, as with TRIAC skf bearing 6004 zjem. By way of comparison, a TRIAC can be visualized as two SCRs, arranged in antiparallel. The soft-starter controls the voltage across the motor through the power circuit, formed by the thyristors, varying the firing angle thereof and consequently varying the effective voltage applied to the motor.
The rotor of the permanent magnet electric motors can take on various configurations, and can house the magnets on both the rotor surface and inside the rotor. When placed inside the rotor these magnets create a difference in the flux permeability between the direct axis “d” and the quadrature axis “q”, that is, the permeability along the direct axis is much lower than that of the axis in quadrature. In this type of configuration, two phenomena of interest occur as the appearance of a reluctance torque due to the permeability difference between the direct axis and quadrature.
This binary is added to the resulting binary by incrementing it. It is verified the existence of a magnetic flux with opposite direction to the magnetic flux produced by the permanent magnet, being able to happen to the demagnetization of the magnet. When we deal with rotors with magnets placed on their surface, the anisotropy is very low and can be considered null because the permeability difference between the direct axis and the quadrature axis is almost non-existent. In some cases we use a rotor in cage with internal magnets and this rotor configuration confers a hybrid character to the motor, being able to execute a synchronous start, directly from the network. mrosupply best prices on baldor
A three-phase induction electric motor is fundamentally a constant speed motor when it is connected to a source of constant voltage and fixed frequency. The steady speed is very adjacent to the synchronous speed, however, when the required torque increases, the speed reduces. We can observe that for the load requesting a high torque at the point of operation, the motor has a lower speed. Therefore, the motor speed is given by the encounter between the torque curve for the motor find here baldor vem3709t and the load curve.
In many industrial uses, variable or continuously adjustable speeds are indispensable. Traditionally, DC motors have always been used in applications where speed variation was required. However, DC motors are expensive, requiring brush and switch maintenance and are prohibitive in harsh environments. In compensation, induction motors are inexpensive, maintenance-free, capable of operating in harsh environments and are usable for high speeds. With the advent of static converter technology, frequency inverters have allowed the dispersion of three-phase induction motors in applications where speed control is required.
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