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  #61  
Old Sat 30 March 2013, 20:38
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Sorry Tom for the late reply. Getting ready for Easter with the kids. Plus they shared their cold with me so I have a double whammy.

It is your choice on a Nema or IEC contactor. IEC is way undersized if you have ever tore one apart. The contact tips are tiny. The company I work for have started to use them to save money. They are less expensive that is for sure. On a lot of our motors we have had to upsize the IEC contactors by 2x their rated value to reduce the pitting on the contacts. IEC tend to stick if arcing occurs when the contacts close and open. Your largest arc is always on the opening and causes the most damage. A 20A IEC contact tips are only a little bigger than an 1/8 inch across. More likely to stick from pitting. IEC's are throw away contactors also. Nema can be rebuilt. We have machines built in the 60's that still have the same Nema contactors in them. If I was allowed, I would show the images from the thermographic surveys done with a FLIR of the different contactors. IEC run hotter and fail more frequently. Unfortunately I cannot as I am bound by confidentiality agreements.

So the bottom line is will they work? Yes. But they are application specific. They are great for the electronic overloads they can provide. It all depends on the electrical design and what they are controls and the arc potential.

I like to think in terms of preventive maintenance and spend more for less hassle later. I only used Definite Purpose Relays and Nema contactors for my heavy loads and main line contactor. I used Ice-Cubes for my signal switching. I was always told the the parts aren't cheap, they are less expensive and the person who bought them was cheap.
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  #62  
Old Sat 30 March 2013, 20:53
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Tom,
Posting pictures works great from Flickr or Photobucket. You do not use up your allotment of space on the forum this way and you can post a larger picture as it is dictated from the BBCode. If you decide to go that way, I will help you with that. As far as which to go with, I would read the fine print on who retains ownership of the photos and make your decision from there.
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  #63  
Old Sat 30 March 2013, 22:24
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
Pete, sorry about the cold thing, leave it to the kids to bring it home.

Well, what is considered a 'heavy load'? And I'm assuming Ice-Cubes are the cheap guys

My biggest problem with any of them is that I don't know enough about what I'm looking at when searching (sensory overload I guess). I got a grip on the IEC contactors because that is what was offered (limited #'s) at places like Factorymation and Automationdirect, however I've done searches of the NEMA type and thousands of different contactors come up with many additional options ranging from $75 to $6000. That's great if I knew how to weed them out or had a more focused source.

Ok, I agree with quality parts. But if I where to use the IEC, I would assume that you would recommend doing a scheduled change out solely based on the potential issues. Is this an option? Because you say the others are repairable means they to have a useful life expectancy and requires maintenance as well.

Oh, I may have to do the photobucket or something, I'll try first before I start asking questions.
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  #64  
Old Sun 31 March 2013, 08:00
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Tom,

Sorry but this will be long for you to understand.

For the most part, the Mechmate design requires minimal high voltage control requirement if any. Most of your input signals are going to the breakout board. We are looking the relay logic side of this only and not the breakout board.

An Ice cube relay can be used for a mild resistive load but it will arc. We use them for vibratory motion control. They last about 2 months with this application and the load is 7A. What it is controlling determines the life span. They will cycle a minimum of 1,000,000 times without failure in optimum conditions. They are best used for signal control in the mA range. That would mean switching the binary on or off logic for a branch circuit. An example would but pulling in a contactor. If you have a 24VDC proximity switch but you are pulling in a Size 2 Nema contactor the inrush current will slowly destroy your proximity switch so you would used the prox switch to control the ice cube relay. The line voltage then goes through the contacts of the ice cube and it controls the Nema contactor. This way your consumable is a $5 product and not a $100 dollar proximity switch. A control circuit in most industrial machinery uses 120VAC and 24VDC controls. You can use only 24VDC but the power supply is larger because of the lower voltage. On the other hand it is safer to work on and troubleshoot. Think of voltage like blood pressure. The lower it is the harder it has to work to bridge the gap. You will have more carbon build up on your contacts with a lower voltage. This raises the resistance and requires more amps to close the circuit. This is another theory vs reality problem that most new engineers learn after the first few years of designing and adjust their designs to compensate.

The nema and iec debate. This is a his or hers debate. If I use an IEC contactor, and I do in some of my panel designs, the working load I expect to see (lets say 18 amps), I will use an IEC contactor rated to handle 40A. This is based on my past history working with them. IEC relays are not to be confused with an IEC contactor. The relay is used for signal switching and therefore are not subjected to high make-break potential that you will see when controlling a motor.

One way to think about a relay is it makes a click sound and a contactor makes a CLUNK sound.

Good example of the differences between
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  #65  
Old Sun 31 March 2013, 08:05
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Wiki def of contactor
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  #66  
Old Sun 31 March 2013, 08:46
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Tom, you say you are using 220V. Single phase or Three Phase design? I used a Definite Purpose Contactor for my main line and dust collector. But I am using 220VAC Single Phase. You can get a 4 Pole 40A (50A resistive heating) for around $50. It is the gap between the extremes.

From your question
"Ok, I agree with quality parts. But if I were to use the IEC, I would assume that you would recommend doing a scheduled change out solely based on the potential issues. Is this an option? Because you say the others are repairable means they to have a useful life expectancy and requires maintenance as well."

If the IEC is oversized, it should last a long time at least 5+ years or longer if the duty cycle is very low. The only way to see if it is starting to fail though is with a thermographic device or it stops working. IEC do not come apart easily and are not meant to disassembled.

The most important thing is to size your components appropriately. You would not support something that weighed 100lbs with something that it's maximum capacity is 100lbs. The same is true with electricity. It needs wiggle room also.
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  #67  
Old Sun 31 March 2013, 13:16
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
Pete THANK YOU! I do understand this better than I thought. Its good to have good knowledgeable people around when you need them, Thanks Again!
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  #68  
Old Sun 31 March 2013, 13:26
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
No problem. Just trying to help.
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  #69  
Old Mon 01 April 2013, 21:17
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
I was in the shop cutting the 17g sheet metal for the control box and the 14g HF shear broke within the first 50", love that quality. I'll pick up another blade tomorrow. A little trick when using one of these type of shears, spray a light film of wd-40 on the metal before you cut (I forgot)
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  #70  
Old Mon 08 April 2013, 20:35
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
Well Box is welded and primed. All I need are the hinges from grainger to weld on and viola! I'll post a pic tomorrow. The box is a little big but is probably good for air circulation, 24" x 24" x 10". Doing my taxes, can't spend too much time on this right now so I'll order some more stuff so it'll be here when I get this tax thing done.
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  #71  
Old Tue 09 April 2013, 06:15
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Tom, my electrical enclosure is 24 x 36 x 10. I find my enclosure does not have any heat problems so you should be fine.
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  #72  
Old Tue 09 April 2013, 16:51
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
Thanks Pete, What do you think of putting a glass window in the box? I think I saw someone with one, thought it was cool
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  #73  
Old Tue 09 April 2013, 20:35
swatkins
Just call me: Steve
 
Houston
United States of America
http://www.mechmate.com/forums/attac...0&d=1273727522
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  #74  
Old Tue 09 April 2013, 21:24
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
I think I might opt for plexiglass rather than real glass.
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  #75  
Old Tue 09 April 2013, 21:49
swatkins
Just call me: Steve
 
Houston
United States of America
Mine is Plexiglass...Only way to go

http://www.mechmate.com/forums/showt...?t=2433&page=3

Details of the box start on post 88...
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  #76  
Old Wed 10 April 2013, 00:33
KenC
Just call me: Ken
 
Klang
Malaysia
Quote:
Originally Posted by Tom Ayres View Post
Thanks Pete, What do you think of putting a glass window in the box? I think I saw someone with one, thought it was cool
Looking cool is enough to justify any extra work
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  #77  
Old Wed 10 April 2013, 02:42
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
Steve where did you find the window kit?
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  #78  
Old Wed 10 April 2013, 05:26
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Window kits are for seeing the events happening inside. The best use of one would be for seeing the leds on your breakout board for troubleshooting.
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  #79  
Old Wed 10 April 2013, 06:39
swatkins
Just call me: Steve
 
Houston
United States of America
Tom here is a link for the one I purchased...they have several different ones to pick from..
http://www.crazypc.com/products/casemods/windows.htm

They are under 20.00
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  #80  
Old Wed 10 April 2013, 11:56
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
I have used 1/4" polycarbonate before with edge trim over the hole in the metal. Use silicone to glue the poly to the steel and drill through the steel and poly then tap the poly and secure with machine screws. If you take your time it will look good but not as good as a standard window kit for a box enclosure.

This is what I use a work but they cost a bit more.
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  #81  
Old Wed 10 April 2013, 19:32
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
Thanks Steve, I'll order one. Good idea Pete, maybe trim in aluminum with rivets or something.
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  #82  
Old Wed 10 April 2013, 20:01
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
Painted the box blue (of coarse) tonight. I've got a lot of blue to clean up, I got in such a hurry to see the first bit of blue on anything that I forgot to lay out some cardboard or paper, oh well, let dry and sand, tah dah!
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  #83  
Old Fri 12 April 2013, 05:45
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
I ordered Bearings from Rick at Superior Bearings last night. I've made necessary mods to the skate for the rails, just waiting on bearings. I should be able to do a little more welding this morning to complete the side rails of the base, just wanted to make sure measurements were correct before proceeding. I really need to set up Flicker so I can post these pics.
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  #84  
Old Fri 12 April 2013, 09:26
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
If you go with Flickr, after you sign in and have photos uploaded. Click on the picture you wish to share from your photostream to show only that photo. Directly above the picture is a button labeled SHARE. Click on it and choose "Grab the HTML/BBCode". Click the radio button for BBCode and choose the picture size you wish to use. Then copy the code out of the text box and it can be directly pasted here. You can edit it if you wish or post it as is. By editing the code you can remove the link text , remove your username which is a link to your photostream or change the link text to something other than what is the name of the photo.

Hope that helps.
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  #85  
Old Fri 12 April 2013, 10:18
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
Thanks Pete, quite helpful. I'll give it a go this afternoon.
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  #86  
Old Sun 14 April 2013, 20:14
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
Welded the Y car this morning. Everything square, flat to the table and ready for a coat of primer and paint.
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  #87  
Old Sun 14 April 2013, 20:17
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Sound like you are making headway. Keep on trucking.
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  #88  
Old Sun 14 April 2013, 20:22
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
Waiting on roller bearings from Rick, should be here by Tuesday. That's when the rail grinding starts-That's when the fun starts.
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  #89  
Old Mon 06 May 2013, 18:40
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Tom, how are the rails coming?
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  #90  
Old Mon 06 May 2013, 19:14
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
Well Pete, Never got to them, the wife has me doing other house stuff (like finishing the bathroom remodel). I did however get the spoil board bolted to the cross members ready for welding. I'll have to finish a cabinet job before proceeding further though. Funny how the customer wants their stuff when you ignore them too long.
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