Electromechanical converter

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Components of electromachines

The basis for an electric machine is the rule of induction with magnetic induction. Such a device includes a stator, or as it is called a constant part( typical for asynchronous, synchronous machines of varying current) or an inductor( for constant current devices) and a rotor, it is called the active or moving part( for asynchronous and synchronous machines of varying current) or an armature(constant current devices).In the role of the constant part for low current current machines, magnets( of a constant state) are actively used.

Structure of the electric motor

Electric motor power

Electrical power is a physical quantity that is characterized by the speed of conversion or transmission of electrical energy. To facilitate understanding, the current flow of electricians is represented as the movement of fluid through the pipe, and the voltage is with the difference in the position of the tiers of this liquid. Electricity, as well as carrying out work, moves from high capacity to low, like liquid. Means the power of the electrician is the amount of work, some done in 1 second, or the speed of the work itself. The sum of the current of the electrician, which is laid through the cross section of the circuit for one second, this is the current strength in the circuit itself.

It follows that the electric power is equal in proportion to the voltage and current strength in the circuit. To determine the current's power, a unit-watt is adopted, in short-W.
For physical calculations it was customary to use the standard formula N = A / t, where N is the power, A is the work, and t is the time.
There are many variants of this formula with different letter designations.

An example of the formula for calculating the power as a physical quantity

Determine the power of the engine

If you constantly use electric machines, you often come across a nameplate in which, in fact, all the characteristics, including power options, are indicated. If you look at the thumbnail image, then among the various parameters you can see the value of power. As you can see, against the inscription the maximum power is 1000 W.But this is not its electrical power, as the consumer often thinks.

The rating plate shown below shows the maximum permissible electric power. Often they write on the rating plate the recommended power and designate it with kilowatts.

So, how is it possible to calculate the used power of a certain engine from its own electrical network. To do this, you need to look at other indicators on the same nameplate of the device being tested - this is efficiency and cosφ.Where EFFICIENCY is sometimes referred to as an abbreviation for efficiency, or the letter η.First, we need to take into account the connection of the useful power of the mechanics on the shaft and the efficiency. With these values, you can easily calculate the power consumed by the motor from the electrical network. We learn from the relation: Pa = P / η.But these are not results yet. It must be remembered that electrical appliances consume both active and reactive energy from the network. When calculating the engine's full power, it is necessary to obtain a ratio from the power triangle.

Nameplate

How to determine the power of the electric motor

In order to calculate the power of a certain electric motor it will take quite a bit: a current source( network), a ruler( caliper), a dynamometer, an ammeter, a sign "of the constant engine C from the number of poles".

So, let's move on to the options for action. Namely, to determine the power of the electric motor:

  • current. We connect the motor to the electric network with a certain load( voltage).Alternately connecting into our sequence in each armature ammeter, we measure the operating electric current of the engine in amperes. Determine the number of resulting current measurements. The sum is multiplied by the stress index, and as a consequence - the power of the electric engine used in watts;
  • in size. We determine the endomentric caliber of the core of the fixed part, its length together with the ventilation channels in centimeters. We learn the repeatability of a changing current in the network to which a certain electric motor and a simultaneous frequency of rotation of the shaft are connected. To determine the unchanged separation, we reproduce the core caliber for a simultaneous repetition of the shaft and multiply by 3.14 and divide by 120( 3.14 • D • n /( 120 • f)) and the repeatability of the network in the same order. Thus, we recognized the separation of the device, characterized as polar. Find how many poles, multiplying the frequent repetition of the electricity network by 60, and divide the amount obtained by the repetition rate of the shaft. Multiply the removed values ​​by two. Based on the solution, we look at the "determining the dependence of the constant engine C on the number of poles" we find our number constant. Multiply the obtained unchanged by the caliber of the core in the square, its simultaneous turnover frequency and length. The resulting number is multiplied by 10 ^( -6)( P = C • D² • l • n • 10 ^( -6)).They gained the value of electric power in kilowatts;
  • power output by the motor. We find the speed of revolution of the shaft of the device being examined by a tachometer in rotations per second. After we take the dynamometer and determine the pulling force of the electric motor. And as a result for determining the power in watts, multiply the speed by 6.28, also by the force and radius of the shaft, the latter measured with a ruler.

Please note! For each engine, the network is designed for a certain number of phases. An example is a three-phase motor, which is designed only for power from a three-phase AC mains.

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