Power of the electric motor depends on parameters of the current proceeding on its windings. For the direct current motor it is necessary just to increase its value. The engines working at alternating current can be turned on in network of bigger frequency. There are special cases when the three-phase electric motor joins in usual household network, then it is necessary to make constructive changes.
It is required to you
- - tester;
- - set of wires;
- - current source from changeable EMF;
- - frequency converter.
Instruction
1. Connect the electric motor to a current source from changeable EMF. Increase its value. Together with it tension on electric motor windings will increase. Consider that if to neglect losses on the bringing conductors which are very insignificant then the EMF of a source it is equal to tension on windings. Calculate increase in power of the electric motor. For this purpose find how much tension increased, and square this value.
2. Example. Tension on windings of the electric motor was increased from 110 to 220 V. How much did its power increase? Tension increased by 220/110=2 times. Therefore engine capacity became more in 2²=4 time.
3. Rewind an electric motor winding. In most cases, for a winding of the electric motor the copper conductor is used. Use a wire of the same length, but with big section. Resistance of a winding will decrease, and current in it and engine capacity in as much time will increase. Tension on windings has to remain invariable.
4. Example. The engine with the section of a winding of 0.5 mm² was rewound a wire with section by 0.75 mm². How much did its power increase if the value of tension is invariable? Section of a winding increased by 0.75/0.5=1.5 times. In as much time also engine capacity increased.
5. At turning on of the three-phase asynchronous engine in household single-phase network, increase its useful power. For this purpose disconnect one of its windings. The braking moment generated during the work of all windings will disappear, and the useful power of the engine will increase.
6. Increase the power of the asynchronous electric motor of alternating current, having increased the frequency of the alternating current proceeding on windings. For this purpose attach the frequency converter to the engine. Increasing on it the frequency of the given current, increase electric motor power. Fix value of power the tester working in the wattmeter mode.