- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Red Curly Hair? What's wrong with that... :angel:
300HP Saw Mill Motor
- Thread starter LibertyEngineering
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Red Curly Hair? What's wrong with that... :angel:
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Reminds me of the naval avionics tech who had a shelf of modules marked "NFG". When a female officer asked him what that meant he replied, "Non-functioning gear, maam."
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Yep. And RTFM means Read The Factory Manual...
ptonsparky
Tom
- Occupation
- EC - retired
Would that be half the size of a Grunion? My spelling may be off.There’s a unit of measure I haven’t used in quite awhile.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Continuing slightly off topic.....
I heard the avionics story from a coworker who got his electronics training in the Navy. He also was very proud of his Navy certificate stating that he had completed a course in Sexual Harassment. He was very good at it!
P.S. I always thought it meant Read This Fine Manual...
kingpb
Senior Member
- Location
- SE USA as far as you can go
- Occupation
- Engineer, Registered
When they say flywheel, are they perhaps meaning flywheel energy storage? This could be used as the inertia needed to support the few seconds power surge caused by the load on the blade. Essentially helps the electric system ride through the fluctuations so the utility is isolated from the effect.
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
Well, I haven't seen it all, but how would you make that work? If you use a chain or a belt to connect the blade and the flywheel you run a very high risk of busting the belt or chain if the saw tries to really decelerate if it hits a tough spot or (God forbid) a spike or piece of embedded chain (it has happened). That leaves making the flywheel a part of the saw blade assembly. Sounds like the definition of the word "kludge".
kingpb
Senior Member
- Location
- SE USA as far as you can go
- Occupation
- Engineer, Registered
Its electrical, not a physical/mechanical connection.
http://energystorage.org/energy-storage/technologies/flywheels
No idea if this is what they were eluding to or not. Energy storage is being used to even out the fluctuations in utility systems. I guess there is no reason why you couldn't do it at the plant/equipment level.
http://energystorage.org/energy-storage/technologies/flywheels
No idea if this is what they were eluding to or not. Energy storage is being used to even out the fluctuations in utility systems. I guess there is no reason why you couldn't do it at the plant/equipment level.
kwired
Electron manager
- Location
- NE Nebraska
Seems you would need to hit an awful big and very hard spike or chain to even make a 300 hp motor groan just a little.
On top of that something tells me such a motor is possibly oversized in comparison to what it normally is loaded to so it can ride through some of the tougher tasks it is subjected to. It may also be driving more then just a cutting blade, or maybe even more than one cutting blade.
jimo144
Member
- Location
- Western Grove, AR Newton County
"... the locked rotor current of a 480V – 3Phase, 300HP motor is 2200A"
This quote stood out in my mind as the answer. Unless I missed it, I haven't seen what I consider to be a simple suggestion. Your Customer already has the VFD to produce the Soft Start. Why not place Fast Blow Fuses between the VFD and the Motor. Select the Size that is appropriate to protect against Motor Lockup and propose it to the POCO. That way if something actually did lock up the Motor it might even protect the VFD, POCO, and the Motor. Just a thought.
This quote stood out in my mind as the answer. Unless I missed it, I haven't seen what I consider to be a simple suggestion. Your Customer already has the VFD to produce the Soft Start. Why not place Fast Blow Fuses between the VFD and the Motor. Select the Size that is appropriate to protect against Motor Lockup and propose it to the POCO. That way if something actually did lock up the Motor it might even protect the VFD, POCO, and the Motor. Just a thought.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
NEVER place fuses between the VFD output and the motor, it's a great way to destroy a VFD...
There is not going to be any "inrush current" when using a VFD, and if you can't stand the current it takes to create the torque that the motor may WANT to develop, then the VFD can be programmed to prevent that from happening, as previously discussed. It's just that there are consequences that must be considered. But don't go adding hardware to it like fuses on the output, the consequences are worse.
Yep. Waste of time. Apart from anything else, the inverter would probably shut off on IGBT desat long before there was enough energy dissipated in the fuses to blow them.
ptonsparky
Tom
- Occupation
- EC - retired
+
Not an engineer by any means, but if contactors are frowned upon when on the load side of a VFD, I do not believe fuses would be a good idea at all. I can have the VFD stop before opening the contactor via control interlocks. Not so with a fuse.
Note: I'm slow
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