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  1. #1441
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    Jan 2011
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    Quote Originally Posted by jhovel View Post
    Thanks guys. Now I can't wait for it to arrive....

    Also received another VFD today: $65 delivered this time. Its a 400Hz model and has no case. It is meant to be built into cobtrol panels in things like lift door controls and commercial washers etc.
    This one is going to be built into a switch panel on my Waldown high speed drill press - so it can be even higher speed
    Pulled the motor off it today and quickly found the star point in the stator. Will make the new connections tonight and megger it (yep another gloat: I bought one of the really cheap ($24) 500 & 1000V insulation tester (megger). Works well.

    Oh one more gloat - and help for anyone who is interested: I have bought 10 IGBTs to retrofit Huanyang VFDs for breaking (FGA25N120ANTD, 1200V 25 A NPT Trench IGBT), If anyone want one PM me they are $1.50 each.... so you too can gloat
    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

  2. #1442
    Join Date
    Aug 2010
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    Near Bendigo, Victoria, AUS
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    72
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    3,102

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    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....

  3. #1443
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
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    72
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    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....

  4. #1444
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    Jan 2011
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    Far West Wimmera
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    Quote Originally Posted by jhovel View Post
    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.
    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

  5. #1445
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    Jan 2011
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    Far West Wimmera
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    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.
    Under normal circumstances it would be a simple decision. I have been looking thru the Aliexpress store you linked to. I can see what you mean.

    Dean

  6. #1446
    Join Date
    May 2012
    Location
    Kimberley, West Australia
    Posts
    176

    Default 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.

  7. #1447
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    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....

  8. #1448
    Join Date
    Sep 2008
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    Riddells Creek, Vic.
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    831

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    Normally 1 meg at 500volts is the acceptable limit.

    Regards,

    Lex.

  9. #1449
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    Jun 2008
    Location
    Victoria, Australia
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    74
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    5,080

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    Quote Originally Posted by jhovel View Post
    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?
    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

  10. #1450
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    Oct 2008
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    N.W.Tasmania
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    Default

    Quote Originally Posted by RayG View Post

    +1 to what combustor said about zapping electronics with Megger's. Disconnect then test in isolation.

    Ray
    + 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!

  11. #1451
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    Quote Originally Posted by Combustor View Post
    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.
    I will add my thanks as well Combustor. Ah, is that name anything to d........? Nah forget it. I have not had any experience with a Megger before, but I do have an electric fence.

    Dean

  12. #1452
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    May 2012
    Location
    Kimberley, West Australia
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    176

    Default 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.

  13. #1453
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    Athelstone, SA 5076
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    Quote Originally Posted by Combustor View Post
    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.
    and that includes any thermistors embeded in motor windings...do not megger as they are low voltage only..if you megger not only will the thermistor be damaged but also the winding

  14. #1454
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    Quote Originally Posted by eskimo View Post
    and that includes any thermistors embeded in motor windings...do not megger as they are low voltage only..if you megger not only will the thermistor be damaged but also the winding
    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

  15. #1455
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    Quote Originally Posted by eskimo View Post
    and that includes any thermistors embeded in motor windings...do not megger as they are low voltage only..if you megger not only will the thermistor be damaged but also the winding
    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.

    Simon
    Girl, 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.

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