For A 5kw Dc Motor The Number Of Slots Per Pole Should Be
- For A 5kw Dc Motor The Number Of Slots Per Pole Should Be Lowered
- For A 5kw Dc Motor The Number Of Slots Per Pole Should Bet
- For A 5kw Dc Motor The Number Of Slots Per Pole Should Be Replaced
DC MACHINE DESIGN PART 7. PROBLEMS ON SELECTION OF NUMBER OF POLES. A 250 KiloWatt, 500 Volt, 600 R P M, 6 POLE DC GENERATOR IS BUILD WITH AN ARMATURE DIAMETER OF 0.75 Meter AND CORE LENGTH OF 0.3. Brushless DC Motors or BLDC Motors have become a significant contributor of the modern drive technology. Their rapid gain in popularity has seen an increasing range of applications in the fields of Consumer Appliances, Automotive Industry, Industrial Automation, Chemical and Medical, Aerospace and Instrumentation. 1 Winding factor harmonics for 4-pole 3-phase integer-slot windings with different number of slots/pole/phase. Example 2: For concentrated windings, the fundamental winding factor increases and decreases as a function of the number of slots/pole/phase as shown in Fig. The number of slots per pole pair should be an odd integer. The number of slots per pole should be at least 9. The number of slots per pole usually lies between 9 and 16. All of the above. A four-pole machine generates 250 volts when operated at 1,500 rpm. If the flux per pole is 1.85 x 10 6 maxwells, the number of armature slots is 45, and the armature winding has two parallel paths, calculate (ɑ) the total number of armature conductors; (b) the number of conductors in each slot.
For A 5kw Dc Motor The Number Of Slots Per Pole Should Be Lowered
| Frequency | Number Of Poles | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| 2 | 4 | 6 | 8 | 10 | 12 | 14 | 16 | 18 | |
| 60-cycles | 3600 | 1800 | 1200 | 900 | 720 | 600 | 514 | 450 | 400 |
| 50-cycles | 3000 | 1500 | 1000 | 750 | 600 | 500 | 428 | 375 | 334 |
where
RPM = shaft rotation speed or revolutions per minute
Hz = frequency or cycles/sec
Poles = number of poles of your motor.
So, for example, if you have a 4 pole motor on 60 Hz then RPM=60*(2/4)*60=1800 rpm.
60Hz is the most common frequency in the US
50Hz is the most common frequency outside the US
Number of armature slots in DC machine
In order to decide what number of slots (more or less) is to be used, the following merits and demerits are considered.
1. As the number of slots increases, cost of punching the slot increases, number of coils increases and hence the cost of the machine increases.
2. As the number of slots increases, slot pitch λs = (slot width bs tooth width bt) = πD/ number of slots S
decreases and hence the tooth width reduces. This makes the tooth mechanically weak, increases the flux density in the tooth and the core loss in the tooth. Therefore efficiency of the machine decreases.
If the slots are less in number, then the cost of punching & number of coils decreases, slot pitch increases, tooth becomes mechanically strong and efficiency increases, quantity of insulation in the slot increases, heat dissipation reduces, temperature increases and hence the efficiency decreases.
It is clear that not much advantage is gained by the use of either too a less or more number of slots.
As a preliminary value, the number of slots can be selected by considering the slot pitch. The slot pitch can assumed to be between (2.5 and 3.5) cm. (This range is applicable to only to medium capacity machines and it can be more or less for other capacity machines).
The selection of the number of slots must also be based on the type of winding used, quality of commutation, flux pulsation etc.
When the number of slot per pole is a whole number, the number slots embraced by each pole will be the same for all positions of armature. However, the number teeth per pole will not be same.
This causes a variation in reluctance of the air gap and the flux in the air gap will pulsate. Pulsations of the flux in the air gap produce iron losses in the pole shoe and give rise to magnetic noises. On the other hand, when the slots per pole is equal to a whole number plus half the reluctance of the flux path per pole pair remains constant for all positions of the armature, and there will be no pulsations or oscillations of the flux in the air gap.
To avoid pulsations and oscillations of the flux in the air gap, the number of slots per pole should be a whole number plus half. When this is not possible or advisable for other reasons, the number of slots per pole arc should an integer.
For A 5kw Dc Motor The Number Of Slots Per Pole Should Bet
Number of teeth/pole shoe = 5 and flux passes through 5 teeth.
For A 5kw Dc Motor The Number Of Slots Per Pole Should Be Replaced
The reluctance of the air gap is inversely proportional to the area corresponding to 5 teeth.