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Re: Craigslist deals
Posted: Thu Aug 07, 2014 10:27 am
by Jeff Pack
Desert Diver wrote:Jeff Pack wrote:Only downside, is when you slow'm down too much , heat builds up in the motor, and the VFD will shut it down.
Jeff, I never noticed this thread had continued till right now. The reason the VFD shuts down when you slow a motor too quickly is because when you reduce the frequency the motor is generating back onto the DC buss of the VFD and most VFD's have no way to put that power back to the incoming line. When the DC bus voltage goes too high the VFD shuts down to protect itself. Most VFD's have a place to hook up resistors so the waste power from slowing down the motor can be shunted to the resistor bank. I have this setup on my small lathe, and have put them on sawmill VFD's. I can set the deceleration time on my small lathe to 1/2 second and it stops like you hit it in the head. In one of the sawmill applications a log running at speed in the same direction as the chipping heads and saws cutting on it could be braked rapidly any time the heads or saws started to go overcurrent. I put overcurrent sensors to protect the resistor banks but have never tripped them and the motors seem to deal with it very well.
Brian
I'm not talking about stop, I'm talking about running them too slow. My stop is set super fast , and works great. Cranking motor speed down too far, and amp draw goes way up, and VFD gets unhappy.
Re: Craigslist deals
Posted: Thu Aug 07, 2014 10:45 am
by Desert Diver
True story. If you have a load that decreases with speed you can get away with 10-15hz but VFD's are not really replacements for gearboxes. They work best set up to run things overspeed. I have run 1800 rpm gearmotors at 5400 rpm for a particular purpose and you get better motor cooling and lower amperage so long as load doesn't go too high with the additional speed. For really low speed running you can put external fans on the motor and adjust the volts/hertz curve to match the motor better.
Re: Craigslist deals
Posted: Wed Aug 20, 2014 11:23 am
by Jeff Pack
Re: Craigslist deals
Posted: Mon Oct 20, 2014 11:43 pm
by fljamis
Re: Craigslist deals
Posted: Mon Nov 03, 2014 4:48 pm
by fljamis
Re: Craigslist deals
Posted: Tue Nov 04, 2014 11:01 pm
by renoun
Re: Craigslist deals
Posted: Tue Dec 16, 2014 6:38 pm
by Jeff Pack
Re: Craigslist deals
Posted: Sun Dec 21, 2014 11:03 pm
by ljjames
Saw this on CL, these are great lights, I have a set that I use all the time...
http://seattle.craigslist.org/skc/pho/4792540587.html
Re: Craigslist deals
Posted: Fri Dec 26, 2014 12:16 pm
by KneeDeep
Re: Craigslist deals
Posted: Fri Jan 02, 2015 12:12 pm
by geo
Re: Craigslist deals
Posted: Mon Feb 09, 2015 10:43 pm
by Gdog
Re: Craigslist deals
Posted: Mon Mar 02, 2015 11:15 am
by finnegankp
http://seattle.craigslist.org/est/spo/4913953535.html
Oceanic Excursion BCD - Well Maintained w/warranty $350 obo
Re: Craigslist deals
Posted: Sat Mar 14, 2015 10:24 am
by ryjoph89
http://seattle.craigslist.org/sno/spo/4931828566.html
Selling a bunch of extra/unused gear that's been sitting around for too long...
Manifold, argon straps, bands, SMB, lift bag, strobe, cave reel, camera, Dive Alert, plus misc extras
Re: Craigslist deals
Posted: Sun Apr 19, 2015 10:53 am
by SealScott
http://seattle.craigslist.org/see/spo/4985787579.html
2 - Faber steel LP80's (+ rated, 2014 hyrdo)
2 - Faber steel LP 95
I messaged with the seller this morning - great guy and willing to answer questions.
Craigslist deals LOT OF TECH GEAR
Posted: Tue Apr 21, 2015 9:27 am
by Norris
Looks like a pretty decent hit, and for 3500 it might be worth it
http://seattle.craigslist.org/tac/for/4973745166.html
Re: Craigslist deals
Posted: Wed May 27, 2015 3:45 pm
by Norris
Re: Craigslist deals
Posted: Sun Jun 07, 2015 1:50 pm
by Gdog
Re: Craigslist deals
Posted: Wed Jun 10, 2015 8:32 am
by KneeDeep
Wow.. that's a great price for 119's
Re: Craigslist deals
Posted: Tue Jul 14, 2015 7:11 pm
by Gdog
Re: Craigslist deals
Posted: Thu Sep 03, 2015 11:04 am
by mpenders
Re: Craigslist deals
Posted: Fri Sep 04, 2015 12:54 am
by bradmond
just bought 2, thanks Mike
Re: Craigslist deals
Posted: Thu Oct 01, 2015 7:07 am
by 60south
$20000 for a turn-key dive training operation (a trailer with all the goodies). Not sure if this is a good deal, just thought it was kind of amazing.
http://denver.craigslist.org/bfs/5232636926.html
Re: Craigslist deals
Posted: Thu Oct 01, 2015 8:00 am
by Gdog
Wow... That is actually quite impressive. In spite of the crappy oceanic tropical bcds. Well organized and thought out.
Re: Craigslist deals
Posted: Sun Oct 18, 2015 11:05 am
by kundalinichi
Re: Craigslist deals
Posted: Sun Nov 29, 2015 11:41 pm
by DiverBob