Rotary Converters:
The ac and dc armature powers will be equal when :
(i) losses are neglected.
(ii) power factor is unity.
In that case the ratio of slip ring (line Current) to the dc output current will be
IL / ID = (2 √ ( 2 ) ) / N
Where
N is the number of slip rings.
N
|
Ratio IL/ ID
|
| 2 | 1.41 |
| 3 | 0.94 |
| 6 | 0.47 |
| 12 | 0.24 |
For efficiency η and power factor cos φ, the ratio will be greater by a factor 1/ η cos φ.
SI. No.
|
Particular
|
Rotary Converter
|
Metal plate rectifier
|
Mercury arc rectifier
|
1.
|
Construction
|
Very difficult to construct
|
Most easy to construct
|
Easy to construct as compared with rotary converter
|
2.
|
Operation
|
Requires great care at the time of starting
|
Its starting operation is most easy
|
Operation easier than that of rotary converter.
|
3.
|
Sound and vibration
|
Produces sound and vibration
|
Soundless and produces no vibration
|
No vibration and soundless operation
|
4.
|
Fault
|
Chances of occurring faults are more due to rotating machine
|
Less chances of faults in it
|
Very less chances of faults
|
5.
|
Rating
|
Can be manufactured for high rating only
|
Manufactured in both small and high capacity
|
It cannot be made in low capacity
|
6.
|
Cost
|
Initial cost if very high
|
Least costly
|
Initial cost is less than rotary converter.
|
7.
|
Maintenance
|
Needs great care and maintenance as it is a rotating machine
|
Requires less maintenance
|
Needs less maintenance as compared to rotary converter.
|
8.
|
Efficiency
|
Fair
|
Good
|
Good
|
9.
|
Life
|
Long
|
Long
|
Very long
|
10.
|
Application
|
It can be used as a dc motor, ac motor, converter and inverter. It is
specially used in sub-stations to convert ac to dc.
|
It is used for battery charging, electroplating, electrolysis, etc.
|
It is employed in substation to convert ac to dc and is superceding
the rotary converters.
|
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