PDA

View Full Version : OK to mount contactor horizontally?



DICKEYBIRD
05-27-2012, 09:30 AM
Telemecanique LP1 D12 10 manual states: "Operating positions Without derating - 30 possible, in relation to normal vertical mounting plane" For space/access reasons I need to mount it lying down on its side.

It's rated for 1 hp @ 120v and I'm using 1 contact to supply the KB controller/.75 hp Baldor DC motor plus another of its 3 contacts to feed a 28V 3A transformer for the CNC controller, various small power supplies for the B.O.B., cooling fans, worklight, etc.

I couldn't find any reference in the manual as to how much of a derating factor to use if it were to be mounted @ 90 deg. from vertical. I doubt that the motor would ever be loaded to full capacity on the little ORAC lathe and it will have good airflow so convection cooling issues shouldn't be a factor. Should I worry about mounting it horizontally?

Paul Alciatore
05-27-2012, 10:36 AM
Boy that is a hard question to answer. You say you looked in a manual for information, but can you get a data sheet? That's where the design information usually is. Perhaps you can find one on-line, most manufacturers post them now. Or a phone call to them may be productive.

Chances are it is all about heat and ventilation so if you have good ventilation that is on your side. Without seeing the design, it is hard to imagine what it is about it that needs a particular orientation. Perhaps there are features that encourage natural air flow. Of course, it also depends on other components in the general area.

Heating in a contactor is generally in the coil, not the contacts. If the contacts start to heat up, it can lead to a degenerative spiral: heat > corrosion > more resistance > more heat (I^2 * R) and back to the the start for more corrosion. This usually results in fairly fast failure. This spiral is controlled by current and age so you have little control. Frequent operation (on/off cycles) can also effect it as heat is generated each time the contacts make or break. But you are mainly concerned with the heat generated in the coil and you also have little control as to how much since it is set by the current and resistance there.

One thing you could do is add a fan if it is getting too warm.

DICKEYBIRD
05-27-2012, 11:41 AM
Thanks Paul; yep I do have a .pdf datasheet from Schneider/Telemecanique...I should have called it that instead of a manual. I couldn't find any mention of a derating factor anywhere. I'm thinking it'd be OK horizontal though especially since there's a lot of airflow in the cabinet.

After the second cup of coffee and kicking back to watch the Monaco F1 race a semi-cobble-up solution hit me. I think I can take off the DIN rail mount off the bottom of the contactor and add a mount tab on the bottom of my sliding electronics tray/heatsink assy. and it'll fit vertically as recommended. Details & pics later on the tray rig.

MaxHeadRoom
05-27-2012, 12:04 PM
I have used Telemecanique pretty much exclusively and so far they have come with optional mounting holes for direct mount if you want that option??
Max.

winchman
05-27-2012, 12:10 PM
Have you considered the effects of friction and gravity on the movement of the contactor parts in something other than the normal upright position?

rdfeil
05-27-2012, 03:36 PM
Winchman +1

The problem is not electrical ratings, but the mechanical stresses. Many contactors rely on springs to hold them OPEN. and the coil pulls them closed. The mechanical design allows for a very light spring to hold them open and therefore the coil can be much lighter to pull the contacts closed.

Now in the real world, for your application it may work fine mounted horizontally, you would just have to try it. Remember the ratings on industrial controls are for 100's of thousands of operations or more without failure. In the home shop the number of operations in the life of the machine will probably be a fraction of the design rating.

winchman
05-27-2012, 04:39 PM
I just did a little test with a three-phase contactor I have in the shop. It's got a 24vac coil, but I was using an adjustable dc power supply.

With the coil axis vertical (which I believe is the normal mounting position), it pulls in at 10vdc. With the coil axis horizontal and either a "side" or "end" down, it pulls in at 14vdc. The release voltage in all cases is around 1vdc.

John Stevenson
05-27-2012, 04:45 PM
Three MiG welders here, all with contactors mounted on their side, Big CNC has 4 contactors, again mounted on their sides.

Never seen a Bridgeport with vertical contactors.

http://www.practicalmachinist.com/vb/attachments/f20/6089d1220047683-bridgeport-electrical-control-box-460v-220v-022-aug-29-2008-photo_0022.jpg#

Ipso facto - case rests.

darryl
05-27-2012, 05:01 PM
Chances are it will be fine. Do a test to see how well it pulls in when you change orientation. Maybe that will show up a possible problem, or maybe not. There are some types of relays that need to be vertically mounted- I have one that's a starting relay for a washing machine motor, and it won't operate correctly unless it's vertically oriented.

I'm tending to think that if a manufacturer has specified anything about the orientation of the relay or contactor, there probably would be some effect to it if mounted otherwise.

DICKEYBIRD
05-27-2012, 06:10 PM
Wow, that's purty John! I see how nicely it's done by the big manufacturers. I won't get anywhere near that level but will do me best.

I have about 17" of that grey plastic wire channel with the snap covers to hide the worst of my rat's nest wiring.;)

I figgered out a way to get the contactor mounted close to vertical and stilll fit where it needs to go so I'm going to go that route. Seeing as how the manufacturer recommends it, I'll mount it that way.

In my Google searching the matter earlier, I did run into numerous contactors that were rated for horizontal use. Dunno what the difference is...different springs or coil slug tube materials? Maybe that's what's in yer Migs & that purty B/Port??

yul m6
05-27-2012, 11:45 PM
I used to work for a french company and we used telemecanique components exclusively. Vertical mounting plane refers to the plane that the base of the contactor is affixed to. So effectively they are mounted horizontally with the wires going in from above and below the contactor, similar to the picture from Sir John. Think about it, if they are mounted vertically as you believe, than half of the wires would be inaccessible, and only the bottom edge of the panel would be usable, which is never the case as it is reserved for cable entrance. LP1 D12 10 has been replaced by LC1 D12, see:

http://www.global-download.schneider-electric.com/852575770039EC5E/all/03922E44D218D9B088257577004D0818/$File/32ac69f.pdf

DICKEYBIRD
05-28-2012, 09:46 AM
Wow, thanks yul; there's nothing like the voice of experience!

I have that document you linked to and all of the mounting dimension drawings are shown with the coil axis horizontal although so far I have found no clear instruction of which way they should be mounted. Your statement and experience sounds correct. The extent of my contactor knowledge came from my home a/c unit which was mounted with the coil axis vertical and assumed that to be the norm since the datasheet mentions vertical mounting.

For a fellow with my skills, the books should have crayon drawings with little stick figures and arrows with captions "OK kiddies, contactors should mount like this here.";)