Motor- Alternator-Coupled To External Primemover
Motor- Alternator-Coupled To External Primemover
(OP)
Hi All,
I Have a tractor which is coupled to a 32kVA alternator which is meant to supply three nos. 7.5HP motors used to extract water from ground for our fields.
When we accelerated the RPM of tractor to get desired water we found that all the motors burnt and the shaft connecting tractor and alternator was also broken, what necessary protections will be needed to protect the system (mechanical and electrical) in future.
I Have a tractor which is coupled to a 32kVA alternator which is meant to supply three nos. 7.5HP motors used to extract water from ground for our fields.
When we accelerated the RPM of tractor to get desired water we found that all the motors burnt and the shaft connecting tractor and alternator was also broken, what necessary protections will be needed to protect the system (mechanical and electrical) in future.





RE: Motor- Alternator-Coupled To External Primemover
You need a system to control the generator's output voltage to the correct rated voltage. ANd prohibit the motors from being driven if the voltage is too low.
You need a frequency monitor to make sure the generator is putting out the correct frequency power. Too low and the motors will burn up. Too high and the motors will burn up.
You should have some ground fault protection to keep from also burning up and breaking the humans that are using the system.
If there is even the remotest chance that the wires could be hooked up differently between usages you need to include phase detection to make sure the pumps don't get run backwards.
You should also have the system set up to start the motors individually with time delays between them.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Motor- Alternator-Coupled To External Primemover
Muthu
www.edison.co.in
RE: Motor- Alternator-Coupled To External Primemover
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If we learn from our mistakes I'm getting a great education!
RE: Motor- Alternator-Coupled To External Primemover
Typically, tractor driven gensets have indicators to show they are operating at the correct speed. The throttle is a level that is manually set. A retrofit to automatically control the throttle would be costly and complex. So, honestly, if you can't trust the operator then the second best way to protect the system would be to install a solid very hard to tamper with throttle position stop that does not allow another experiment.
On the electrical side, you should look at motor overload relays and a over-frequency relay to turn-off the generator power if someone tries that again. You may also have to install a breaker with a trip coil in it so it can turn off the output.
RE: Motor- Alternator-Coupled To External Primemover
Rafiq Bulsara
http://www.srengineersct.com
RE: Motor- Alternator-Coupled To External Primemover
Most tractors that I see have quite a good governor. It will hold a set speed quite well. Most tractors have a notch or mark on the throttle quadrant marked P.T.O. That is where the throttle should be set for the proper speed at the Power Take Off.
Check that the ratio of the reduction gear ahead of your alternator matches the PTO speed.
Bill
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"Why not the best?"
Jimmy Carter