What quantity of turns has the asynchronous electric motor?
Sometimes in the course of work it is necessary to define quantity of turns of the asynchronous electric motor on which there is no label. And not each electrician can cope with this task. But it is necessary to understand it. It is very easy to define quantity of turns of the electric motor and simply.
We determine it by the winding. For this purpose it is necessary to uncover the engine. It is better to make it with the back cover since the pulley or the semi-coupling should not be removed.
It is enough to remove the casing of cooling and the impeller - and the cover of the engine will be available. After removal of the cover the winding it is visible rather well. Find one section and you watch how many places it takes on circumference (stator). And now remember: if the coil occupies the half of the circle (the 180th hail.), it is the engine on 3000 rpm.
If circles hold three sections (the 120th hail.), it is the engine of 1500 rpm. If in the stator four sections hold (the 90th hail.), this engine on 1000 rpm.
Here it is so absolutely just possible to define quantity of turns of the "unknown" electric motor. In the provided drawings it is visible well.
The method of definition approaches when coils of windings are reeled up by sections. And there are windings "vsypny", and here given by method will not approach. But "vsypny" windings meets seldom.
There is one more method of determination of quantity of turns. In the rotor of the electric motor there is the residual magnetic field which can direct small EMF in the stator winding if we rotate the rotor. This EMF can be "caught" the milliammeter. Our task consists in the following: it is necessary to find the winding of one phase irrespective of as windings, are connected by the triangle or the star. We connect the milliammeter to tips of the winding. Rotating the engine shaft, we watch how many times will deviate the arrow of the milliammeter for one turn of the rotor.
Here according to this table it is possible to look that for the engine before you:
- (2p) 2 3000 r/min;
- (2p) 4 1500 r/min;
- (2p) 6 1000 r/min;
- (2p) 8 750 r/min.
In the USSR the TCh10-R device was issued, maybe, at whom remained. For those who did not see and did not know about such measuring instrument, apply the photo. In the set there are two nozzles: for measurement of turnovers of the axis of the shaft and for measurement on the shaft circle.
It is possible to measure quantity of turns and by means of the digital laser tachometer
- Range: 2,5 rpm ~ 99999 about / ми.
- Permission / step: 0,1 rpm for range 2,5 ~ 999,9 rpm, 1 rpm 1000 rpm and more.
- Accuracy: + / – 0,05%.
- Working distance: 50mm ~ 500mm.
- Also the minimum and maximum value is specified.