Electric motor power, as a rule, is specified in technical documentation to it or in the special plate on the case. If so it cannot be found, calculate it independently. It can be done, having measured current in windings and tension on a source. It is also possible to determine its power by the sizes. Useful power pays off on the frequency of rotation of a shaft.
It is required to you
- - tester;
- - table of dependence of a constant of the engine on quantity of poles;
- - dynamometer.
Instruction
1. Turn on the electric motor, having connected it to a current source with a rated voltage on which it is calculated. Connect a tester consistently to each winding, having tuned it into measurement of current. Find the work of current on each winding and tension. Put the turned-out results. It will also be the rated power of the electric motor. Measure tension in volts, current in amperes, then receive engine capacity in watts.
2. To determine electric motor power, without connecting it to an electrical network, make such actions: 1. Measure by a caliper the internal diameter of the core of the stator and its length in millimeters. 2. Determine current frequency in network. 3. Determine the synchronous frequency of rotation of a shaft. 4. Increase number 3.14 by diameter of the core and synchronous frequency of a shaft. Divide result into number 120 and frequency of current in network. The turned-out number – polar division of a scale. 5. Find quantity of poles, having increased current frequency by 120 and having divided into the frequency of rotation of a motive shaft. 6. According to the specialized table, on crossing of values of polar division and quantity of poles find an electric motor constant. 7. Increase a constant by diameter of the core in a square, its length and also synchronous frequency of rotation. For obtaining power in kilowatts increase result by 10^(-6).
3. For determination of useful power of the electric motor by means of the tachometer measure the frequency of turns of a shaft in Hertz (number of revolutions per second). Determine by a dynamometer the traction effort developed by it. For this operation it is the best of all to use the special stand. To define value of useful power of the electric motor, increase number 3.14 by the measured force, frequency of rotation of a shaft, and its diameter.