Which gearbox and coupling are suitable for reducing RPM in a generating unit?

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Discussion Overview

The discussion revolves around selecting a suitable gearbox and coupling for a generating unit that requires a significant reduction in RPM from 15,000 to 250-300 RPM to achieve a 50Hz output. The conversation includes technical specifications and considerations for the gearbox and coupling types.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant inquires about the correct input RPM, questioning whether it is 15,000 or 1,500 RPM, and expresses confusion regarding the need for a 250-300 RPM output.
  • Another participant emphasizes the importance of specifying the power and torque requirements for the gearbox, suggesting that these factors are critical for selection.
  • A participant provides specific details about the generating unit, including power output (25KW), input power (45 hp), and the need for a gearbox that is efficient, cost-effective, and low noise, while also considering AGMA class ratings.
  • One suggestion includes exploring GlobalSpec.com for gearbox options, noting potential challenges with the high input shaft speed and proposing the idea of using multiple gearboxes in series for further reduction.

Areas of Agreement / Disagreement

Participants express differing views on the input RPM and the necessity of reducing to 250-300 RPM, indicating a lack of consensus on the initial parameters and requirements for the gearbox selection.

Contextual Notes

Participants have not fully addressed the assumptions regarding the gearbox's power transmission capabilities, torque requirements, and the implications of the high input shaft speed on gearbox selection.

arjun.b
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Hi,

I have a elec generating unit. The shaft has a rpm of 15000. Need to reduce to 250-300rpm i.e. bring it down to generating elec at 50Hz. Could somebody suggest which gearbox is suitable for this application to reduce from high to low rpm. Also suggest which type of coupling has to be used between the shaft and the generator.

Thank you...
 
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15000rpm or 1500rpm?

How big is your generator? Most commercial generators run at 1,500rpm, not sure why you're after 250-300rpm.
 
The gearbox's reduction is only one requirement that you will need to specify a gearbox for your application. The most important things you haven't mentioned yet is how much power will this gearbox be transmitting, and in a related vein how much torque on the input and output shafts?
 
Power generated: 25KW
Input power: 45 hp (33.6 kW)
axes: parallel
low speed shaft: 3000rpm
high speed shaft: 15,700 rpm
center distance: 3.125-inches (79.375 mm)
spur gear or low helix angle (whichever is more efficient, less expensive and low noise) ?
AGMA class 9, 10 or 11 (depending on cost)
life: 60,000 hrs
 
Take a look at GlobalSpec.com's Gearboxes and Gearheads search. They have a lot of different stuff in there, and you can narrow your search one parameter at a time (for example, reduction and power throughput). It sounds like you could have some trouble based on the input shaft speed (15000 rpm) but who knows you might find something...

http://www.globalspec.com/SpecSearch/Suppliers/Motion_Controls/Drive_Components/Gearboxes_Gearheads

If the input shaft speed does become a problem, you might consider stacking a pair of gearboxes, one reducing from 15000 rpm to around 3000, and then another gearbox that reduces to your final shaft speed.
 

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