Method B of IEEE 112 refers to loss-of-loss input-output and indirect measurement of load-dispersion losses. It is applied to horizontal squirrel cage polyphase type electric motors in the 1-250 hp range.
For the results of this procedure to be satisfactory, we must observe some recommendations, regarding the treatment of data and instruments and equipment used.
For electrical quantities we must adopt some procedures:
– All measured quantities must be in rms values; The power supply must provide balanced sinusoidal phase voltages; The frequency shall be maintained at ± 0,5% of the value required during the test; The voltages shall be measured at the motor terminals and the maximum voltage unbalance shall not exceed 0,5% of the average of the voltages; The currents of each phase of the motor must be measured; The input power of the three-phase machine shall be measured by two single-phase wattmeters, connected in accordance with the two wattmeters method; Stroboscopes or digital tachometers are recommended; We must adopt a safety procedure, since forces, tensions and currents that may be dangerous to health are involved. sealmaster bearings
Although the mechanical construction of DC motors and generators is very similar, their functions are quite different. The function of a generator is to generate a voltage when the conductors move through a magnetic field, while an electric motor serves to produce a rotation effort, or torque, to produce mechanical rotation.
There is a magnetic field around a conductor conducting electric current. When this conductor is placed in another magnetic field, the two fields interact.
Magnetic fields in the operation of a motor never cross; The lines of the two fields accumulate on one side and cancel each other on the other side, producing, respectively, strong and weak fields.
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The interaction between the magnetic fields, main and the conductor of the armature, places the flow lines with the same direction, which tend to repel. Thus, the lines under the conductor when repelling, move the conductor upwards or, when the direction of the current in the conductor is inverted, to move it downwards.
The movement of the conductor causes it to cut the lines of the main magnetic field, according to Lenz’s law, opposing the movement that produced it.