# How to determine the power and motor current

Simply use the current clamp, the lack of one thing. In idle mode, even at high engine revs powerless to develop full capacity. Below we give a table, according to which it is possible to judge the regime of the device parameters. It does not solve the whole problem. Let's see how to define the power and motor current simple methods.

## Determination of the motor current

Simply use a current clamp. A device for remotely enabling to estimate the magnitude of the magnetic field around a single wire. Covering ring cord, we obtain a value of zero. The fields are oppositely directed phase and neutral conductors. Work will need to make the socket with separate wires, shown in the picture. we see:

Socket measuring Clamp

1. Wooden base. The obvious way out, decided to mount the socket on the insulator. Simply get a small scrap boards.
2. Invoice socket shown in exploded view: a base body are separate.
3. With the power cord removed insulation, to cover each core separately.
4. Find collapsible plug. Do not use for high-power devices, but we perform measurements short period of time, accompanying full control. Either buy a standard power strip in the store, the power cord deprive external insulation.

Mounting socket base

The socket is mounted on the board, take the trouble to securely clamp the wires blocking the possibility of breakage, slippage. Simply do this by using a scrap insulation shown photo. Presses screws, long life test an outlet provided. When dressing the body need to wind a bit of electrical tape around the cord for better clamping. The result was an auxiliary tool measurement Clamp.

Worth the appliance, which is known to power. For example, take an electric drill with a commutator motor, start to measure current. At idle value is below nominal. It has been observed during acceleration, the engine requires full power, instant issued mites screen close par. For example, for the device on the photo - 3.2 A, at a voltage of 231 volt outlet provides 740 watts (nominal 750 watts). When you start to be seen: the current rises sharply, then falls rapidly. It is believed to have time to detect the top of the mountain.

Measuring the current consumption of the drill

Note: Clamp Meter give evidence at regular short intervals, it is difficult to detect the peak of the first half. Put the highest speed of the spindle, press the trigger patiently, trying to catch the top. We managed the third time. To make the picture fit the experience was performed half a dozen times (the shutter is released with a delay, it was difficult to catch the moment). And then I get a photo of only 3.1 A (think readers believe the authors about 3.2 A). During the experiment, it was prepared 4 A single value that refers to random jumps supply current plus the error. You sure: the peak is repeated (at least 2 times out of five).

As a result, approximately determined power commutator motor of electric drill. Just want to say that there is no unique dependence on the power of the current nominal idling current. In nature, there are quite complicated formulas, use them quite difficult. Apply a little - that complicated. Is a table of exemplary relations asynchronous type motor, taken from the site http://energo.ucoz.ua/. Where to get the authors, it remains a mystery, the attention given the opportunity to understand how to assess the nominal motor power for the idling current. Expected nominal voltage, bulky devices need to warm up before work. So says GOST R 53472. The period determined by the type of bearings.

Current idling engines

Afraid to make a mistake, take the maximum value:

1. Up to 1 kW heating time is below 10 minutes.
2. Rated power 1 - 10 kW, while a half-hour warm-up.
3. The nominal power of 10 - 100 kW and the heating time up to an hour.
4. Rated Power 100 - 1000 kW, the heating time up to two hours.
5. The nominal capacity of over 1 MW, heat-up time of up to three hours.

As a rough estimate the capacity? Explains. List given wishing to measure precisely. To estimate using the table, avoiding score brains. Commutator motor to drill the measurements at room temperature of not completely warmed up. Most readers devoid of clamp. Most multimeters allow to measure current, limited by the size range 10 A. Note the red wire should be connected to the other socket (shown in photo) at the maximum limit.

Select a connection socket

Near the openings in Russian (in English) written with the operation mode measurements is not more than 10 seconds (MAX 10SEC) followed by a break quarter of an hour (EACH 15MIN). Otherwise multimeter operability can not be guaranteed, without a fuse entrance (UNFUSED). Tells instruction. Multimeter cuts into the circuit. One wire is required to open the measurements. Together we think if economically profitable.

Look at the picture of checks. Klemmetr includes current clamp, simple tester indicated 1SK. It can be seen, both devices are cheaper than 400 rubles, because the economy needs both. The meter will assess current up to 10 A, a very short time. Ticks work much coarser scale reaches a limit of 1000 A The conclusion is obvious - need to roughly determine the motor current is applied, "klemmetr". You need accuracy, use a tester (rated current below the limit).

Cost clamp

## Measure motor power

Motor power is made up of active, reactive components. Businesses set punitive tariffs. Because it is important to understand the measured values. Manual clamp writes evaluate RMS current. Pure mathematics. These things means: device fetches a certain interval, taking the root sum of squares of individual measurements, divided by the total number. Liken averaging over a certain period of time.

Active current, complete, reactive (unlikely). Question useful to know: current clamp, the photos shown, punctually provide power devices at 11% below face value. Checking electric heaters, irons, hair dryers. Power understated single value. Literature writes rms value (RMS) shows the full current value. Physically flows through the wire. The calculation is for sine wave will be the variation in non-compliance with requirements.

Current clamps are simply lying. would show an active part for the engine values ​​would be significantly lower than the heater. Load pure resistance, winding give a strong imaginary component. Requires calibrated current probe before use. Make the easiest way using purely resistive heaters (oil). Possibility clamp to measure active power alone is usually specified instructions. Professionals say similar products - the fruit of imagination of amateurs.

Engines give a greater load in the jet range. People tolerate or put condensing units, compensating inconsistency, leveling phase. About these household products can be read on websites selling instruments like Ekonor. Sense box like unit capacitors compensate for the reactive power. Note: for professional stations specified limit, expressed BAP for Ekonor parameter is ignored. One radio amateur counted number. It appeared 150 VAR compensated.

Probably enough for low-power devices, the engine will elephant's grain. Asynchronous machines provide 40% of the reactive power is wasted energy. Good penny. Note: Problems added in isolated neutral. The current flows in one phase, out - another. The effect can be deducted. Current clamp can not be considered the best option.

It is better if the neutral grounded. Total current follows the neutral conductor where the measurement. Isolated neutral - it turns out, the effect of one wire will measure twice, input, output. Try three values ​​add up, then divide by two. Rough technique will approximately correct.

Attachment clamp

## Calculate motor power consumption

We offer to determine the type of engine. It helps to make the label. Indicates the total power (active plus reactive connected through the cosine of phase angle, called the power factor). If you know the type of engine (found, guided by images, appearance), reference will allow to find the power. No wonder: the dimensions are closely linked with the parameter, each manufacturer wants to save as much as possible the release of products. The dimensions are optimized, a typical set of parameters is as follows:

1. The diameter of the shaft.
2. The height of the axis of the base (frame).

AIR motors are described, dimensions, capacities are listed here: http://wp.electrostal.com.ua/kakoy-diametr-vala-u-elektrodvigatelya/. Accordingly, it is possible without the tools to understand the details. You'll see the same kind of information will be found on virtually all types of engines. Label ripped off, you can spend some time, looking like a model on the Internet. Russia gives China a variety of electric motors. The success rate is high.

We believe are the available methods for determining the power, current, small problem to spend 1,000 rubles to obtain the necessary funds. Taking into account that the ruble burns step will seem reasonable. Simply determine the power of the electric motor, using a reference. You need to know the model, measure the shaft with a caliper.

We finish the review, we hope, regular readers know the differences of the induction motor from the collector. Differences omitted. Please also note that high inrush currents suffer asynchronous motors. In collecting the spread is low.

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