Results 1,441 to 1,455 of 2682
Thread: todays tools gloat
-
7th Jun 2014, 10:57 AM #1441
Could you point me to the megger Joe? One of these would be useful for the drill press motor, and you are starting to convince me about your Hengtai VFD's. Besides, I love buying stuff like this.
I was going to change my lathe coolant pump for a pond pump or similar. I thought the pump would be the old pos from the Nuttall. (lots of stuff got swapped around) but when I took the cover off not long ago, I discovered that it had been upgraded to the 1/4 Hp version sold by H&F. I wish they had told me and given back the Nuttall pump at the time. This pump is sold for $267 retail. It makes sense to use it if possible. One of the Hengtai VFD's might just be the cheapest way to do it. I have just remembered about the 1Hp 3ph motor drivng the wheel on the cylindrical grinder I got off Harty, not to mention the shaper, which does not have a motor at this stage. I wonder if that huge old 3Hp off the Nuttall would work after being out in the rain for years?
Dean
-
7th Jun 2014, 12:53 PM #1442
Dean,
thus http://www.ebay.com.au/itm/400629695149 is the 'megger' I bought.
For my source of VFDs, have a look at this page: http://www.aliexpress.com/store/grou...256261332.html
If there are any that interest you, let me know and I'll see what prices are negotiable with the store. By the way, it takes a good bit of rooting about finding out what it actually is they sell. They can't read English and rely on someone else to translate their pages.... Many of the photos are NOT the items they are advertising and they have no technical knowledge: the VFDs certainly do NOT output 380V no matter how many ads say they do.
But, their sales person, 'Bill Gates' (actually a girl) will go out of her way to find the correct information once the relationship is established. This appears to be fairly typical Chinese business practice and actually works. Then you can also negotiate prices and conditions.
There are a couple of others who are after cheap VFDs, I'd be quite happy to negotiate a 'group purchase'. Let me know by PM.Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
-
7th Jun 2014, 05:08 PM #1443
Stuart and others,
the 'how to' of fitting the breaking circuit parts missing in most if not all Huanyang VFDs is on the Mach3 support forum. I linked the details in the Huanyang thread here: http://www.woodworkforums.com/showth...09#post1775209
If anyone wants me to pull all the relevant bits together for this forum I could do that too..... It's pretty easy to follow though.Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
-
7th Jun 2014, 07:30 PM #1444
Thanks Joe. I have it on my list to buy. As far as the VFD goes, at the moment I need one for the 1/4 hp coolant pump. I only need it to provide 3ph power so that is a simple decision. I will need to look at the motor for the Delta connection. I am not looking forward to pulling it out. Yuk.
Dean
-
7th Jun 2014, 08:17 PM #1445Thanks Joe. I have it on my list to buy. As far as the VFD goes, at the moment I need one for the 1/4 hp coolant pump. I only need it to provide 3ph power so that is a simple decision.
Dean
-
7th Jun 2014, 09:45 PM #1446Senior Member
- Join Date
- May 2012
- Location
- Kimberley, West Australia
- Posts
- 176
Meggers--Caution!
For those who have not handled them before, a word of caution. Be very sure that there are no solid state devices attached to the part or circuit being tested, as the 500 volts or more that they apply can do permanent damage. Isolate each component or winding before applying the megger to it. Keep your fingers clear of the terminals as 500v delivers a most unpleasant bite. Most electrical apprentices can vouch for that. Very useful tools but treat them with caution and respect. Combustor.
Old iron in the Outback, Kimberley WA.
-
7th Jun 2014, 11:50 PM #1447
Thanks for the warning!
By the way, what is an acceptable resistance value between motor windings and the motor body? I find that one one my motors has infinite resistance up to 500V but measures a resistance at 1000V - although it is a couple of hundred Mega Ohms.... And what does that acutally mean?Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
-
8th Jun 2014, 12:06 AM #1448Golden Member
- Join Date
- Sep 2008
- Location
- Riddells Creek, Vic.
- Posts
- 831
Normally 1 meg at 500volts is the acceptable limit.
Regards,
Lex.
-
8th Jun 2014, 12:26 AM #1449
That means it's good.
When you get one where the insulation is breaking down, you'll see much lower values.
+1 to what combustor said about zapping electronics with Megger's. Disconnect then test in isolation.
Ray
PS.. I picked up this little gem a few weeks back.. http://www.ebay.com.au/itm/221430935...84.m1439.l2649
-
8th Jun 2014, 12:36 AM #1450Diamond Member
- Join Date
- Oct 2008
- Location
- N.W.Tasmania
- Posts
- 1,407
+ another 'cos if you zap the semiconductors with the megger, all that smoke gets out usually without you even seeing it, and sometimes even more smoke gets out when you connect it to the mains supply. I haven't done it myself, but I was once nearby when someone else did it, and he wasn't too happy for a while, and neither was his boss!
-
8th Jun 2014, 11:07 AM #1451
-
8th Jun 2014, 11:49 PM #1452Senior Member
- Join Date
- May 2012
- Location
- Kimberley, West Australia
- Posts
- 176
What's in a Name?
Can't link the name to any pyrolitic event that I am prepared to admit to, but after trying to sign onto several old engine and machinery sites under various names, I finally found an acceptable one that reflected my interest in internal combustion engines, and have been too lazy to try and find another acceptable username fot this site. Murray in the Kimberleys, alias Combustor.
Old iron in the Outback, Kimberley WA.
-
9th Jun 2014, 02:34 PM #1453Most Valued Member
- Join Date
- Jul 2006
- Location
- Athelstone, SA 5076
- Posts
- 4,255
-
9th Jun 2014, 10:08 PM #1454
I would have thought that a thermistor would be on a seperate circuit so obviously you would not want to megger that circuit. Are you saying that there could be a thermistor in one of the actual motor windings, hence the damage? As a newbie I want to be aware of any risks to my pocket.
Dean
-
10th Jun 2014, 09:18 AM #1455Most Valued Member
- Join Date
- Aug 2011
- Location
- Melbourne
- Posts
- 4,779
I've seen plenty of motors with thermal switches that are series wired in with the windings but never noticed a motor with a separate "thermal circuit" with a thermister. I assume it would be pretty obvious since it would have an extra 2 wires, and they would be much thinner.
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.