1.
The working principle of a DC motor is that when the current is kept in
the same magnetic field, the rotating force is applied to the
conductor.
2. Insulation resistance of electrical machines operating at medium voltage should not be less than 1 Megaohm.
3. The characteristic of a shunt generator is that the voltage of this generator decreases slightly at full load.
4. The level compound generator of course gives stable voltage output at all loads.
5. DC. Motor speed, back emf Is proportional to and opposite to the flux.
6. Some The maximum electrical carrying force is produced in the armature when the rate of change in the DC generator is maximum.
7. The method by which the electrical carrying force (EMF) is generated in a DC generator is called a dynamic method.
8. In general The resistance of armature wiring of D.C. machines is about 1 Ohm.
9. A 220 volt DC Motor whose armature resistance is 0.2 Ohm and Bank EMF If 215 volts, it will take a current of 25 amperes.
10. Interpoles are used to prevent commutation.
11. In DC generators, interpolation fields are made in series of connection armature of coils.
12. Do not touch the wires while measuring the insulation resistance with the help of a magger, otherwise it may get a shock and the reading will be less than the actual reading.
13. The speed of the DC series motor is infinite at no load.
14. A 4 pole simplex layer wound armature consisting of 48 slots, each slot has 4 conductors and the resistance of each conductor is 0.1 Ohm. The value of the total armature resistance will be 2 ohms.
15. According to Fleming's right hand rule, the thumb, middle finger and index finger should be at right angles to each other.
16. If separate excited If the direction of rotation of the D.C. generator is changed, the polarity of the spool also changes.
17. 1 To increase the value of insulation resistance the heating should be heated and dried before varnishing.
18. In 1 generator, the connections of the interpols are done in series of armature and the polarity of the interpol is kept same as the next pole in the direction of rotation.
19. The resistance is usually a few ohms when the DC motor is started.
20. The number of parallel paths including 2 Pole D.C. generator duplex lap windings will be 4.
21. If the series motor is started at no load, then its speed increases very fast.
22. When a single-turn loop is rotated in a magnetic field, the electrical carrying force generated in this loop reflects the properties of the alternating current.
23. In order to minimize brush content resistance, brushes with less area should be used with more tension.
24. If the field winding connections are interchanged, the residual magnetism can be eliminated.
25. The A dc shunt motor is running at no load, if its field winding is opened then the motor will start running at high speed.
26. DC. To obtain maximum efficiency in the generator, the position of the brushes should be placed on the magnetically neutral axis.
27. Distortion due to armature in main plexus is caused by current in armature conductor.
28. The DC series motor is very useful for traction work because its torque is proportional to the square of the armature current and the speed is inversely proportional to the torque.
29. Separtely excited In the D.C. generator, field Can be connected to the supply.
30. Brushes of soft graphite whose contact area is 5 sq. Cm. If the current density is 9 amperes / sq cm it can flow up to 45 amperes.