Replies

1. 
   MajorWool | Oct 09, 2002 11:21am | #1

   Why would you have it on a dedicated 40A circuit? The one I just saw in the store was wired with 14/3, which suggests a 15 or 20 A is more appropriate.

1. 
   jeffn7 | Oct 09, 2002 04:55pm | #2

   13 amps is more likely. The capacity of the circuit is academic, insofar as it is not undersized for the application. The point I was making is that the saw is not overloading the circuit it is plugged into, but rather the circuit from the mag switch to the motor.

   my shop is wired with a range of high capacity 230v circuits, it's just easier to oversize things up front in the event you actually need the extra amperage.

2. 
   LRutherfor1 | Oct 09, 2002 05:52pm | #3

   Motor protection/overload breakers, and circuit breakers will become more sensitive as they get older and have been tripped.  The more they have tripped in the past will cause them to trip with less ampacity than the rated amount.  You might want to replace the internal overload breaker in your saw.

   As far as having a 40 amp breaker for a 15 amp saw, and if your internal wiring is 14 gauge, the wire or internal breaker(s) will trip or burn before your panel's breaker will trip.  Number 14 wire is only rated at 15 amps.  My advise would be to reduce the size of the breaker in the panel to a 15 amp.

   Good Luck, Len

   (Len's Custom Woodworking)

1. 
   jeffn7 | Oct 09, 2002 07:36pm | #4

   thanks.

   Just to be clear, I am not running 14 guage... my circuit is wired with 10g and I replaced the power cord on the saw with a new one that is also 10 guage (I needed a longer cord to reach the outlet, I prefer to replace with a longer one instead of just adding an extension cord.)

   The sensitivity issue you raised is why I asked about the adjustment on the reset button inside the mag switch. It would appear that the engineers have factored this into their design for the reason you stated. Also, the saw is a year old and the tripping problem has only surfaced recently.

1. 
   BarryO | Oct 09, 2002 10:10pm | #5

   You should change out the 40A breakers to 30A.  10 gauge wire is only good for 30A.

   Do you have the 3HP or the 5HP Unisaw?  I'm guessing the 3HP.  In that case, the 40A is too much, and doesn't provide much protection to the motor.

1. 
   HowardAcheson | Oct 09, 2002 10:40pm | #6

   The function of a breaker is to protect the wiring in the walls, not the appliance or motor. Motors have their own internal protection.

   As long as the breaker does not exceed the amperage capacity of the wire, the breaker is OK.

3. 
   DouglasABaker | Oct 10, 2002 07:24am | #7

   Leave the poor guy alone already!  He asked for help in figuring out why the internal circuit tripped - not a critique of his choice of circuit sizes!  40A, 20A, 30A, 10000000A - it's irrelevant - he isn't tripping that breaker, he's tripping his saws internal one!

   JeffN7 - you aren't likely to get the answer you are looking for on this board unless a Delta rep happens tobe lurking.  Suggest you call their 800 number and just ask them (I even did the research for you - 800-223-7278 (US), 800-463-3582(CA)- at less than 1 year old, I'll be surprised if they don't just ship you a whole new assembly...

   Good luck - I wouldn't suggest trying to play with it unless under the guidance of Delta - either you know how it works or you don't - too much potential for screwing it up...

   d-

1. 
   jeffn7 | Oct 10, 2002 07:41am | #8

   d-

   thanks, I was getting a little fatiqued with the breaker questions.

   here's what Delta told me:

   ---- begin  ----

   1) Set the little arrowhead on the blue reset button towards the "R".

   2) Set the main arrowhead towards the "Auto", this tells the unit to 'automatically reset' after an overload.

   3) DO NOT set the calibration dial any higher than the nameplate amperage figure that is on your motor.

   If the main dial is already set at the nameplate amp level and it is tripping out, you need to get you an amp meter and find out how many amps you're pulling under load. If you're pulling more than the nameplate amp figure, the overload is doing exactly what it is supposed to in case of being overloaded...shutting down.

   Ultimately, make sure you have at least 210 volts at the saw and check the amp draw. That should put you on the right track to solve this.

   ---- end ----

2. 
   RSRose | Oct 11, 2002 07:30am | #9

   d-

   Discussion forums such as this often result in more information that the questioner asked for. Take it or leave it. No one has to read anything he or she wants to ignore. A benefit here is that others may percieve a problem that the questioner never realized.

   "Leave the poor guy alone" is a bury-your-head-in-sand-response that's frankly repulsive. I'm glad that most don't ascribe to your restrictive rules. If we did, replies here would be narrow, dry, technical recitations from tech manuals.

   -end of rant-

   Rich

1. 
   purswell | Oct 12, 2002 05:12am | #10

     Here's one- I have a 2 month old 3 hp unisaw.  Its on a 30 amp breaker, with #8 wire.  I have 240 volts.  There is nothing wrong with that end of it.  However, if I try to start it twice within a span of five minutes, the saw's overloads trip out.  The contactor sucks in clean and smooth.  I've megged the motor, it checks out.  There are no loose wires, the overload is set to trip at 14 amps, when the saw runs, it draws 12.6. So it is set at less than 125%.  Once it is going, it runs just fine.  If I turn it off, check a measurement and turn it back on, it hums for a second and trips out.  Then I'm 5 minutes until I can turn it back on and get it to run, and does just fine after that cooling off time.  I regret that each time I've called Delta (its been happening for a week now) I hang up after 15 or 20 minutes on hold- I can't stand it. 

   In my mind it has something to do with start up amperage, and the heat that is generated doing so- so where do I go from here?

     Any advice?....Other than learn some patience on the phone?

1. 
   Upraiser | Oct 12, 2002 05:49am | #11

   You might try stopping by a local motor shop. They might have some advice.  I find my local shop always ready to help, usually tell me to bring it in.

    My best guess, it needs to go back to Delta.

2. 
   HowardAcheson | Oct 12, 2002 08:08pm | #12

   You might want to go over to the WOODNet site and go into their tools forum. There are a couple of Delta guys that hang out their and they are generally pretty helpful. Look for "Delta007" or "rock2car".

   http://www.Forums.WoodNet.net/

3. 
   TKanzler | Oct 12, 2002 08:20pm | #13

   PURSWELL-

   Here are a couple of things to check. 

   Its on a 30 amp breaker, with #8 wire.  I have 240 volts.  There is nothing wrong with that end of it.  Just for the heck of it, have someone read a voltmeter while you are cutting, especially with the saw working hard.  It's not likely the problem (you'd be experiencing motor bogging), but it's good to have hard data at hand.  Check voltage at the motor control, not at the panel, but do be careful.  240V through the heart wouldn't be good. 

   ...when the saw runs, it draws 12.6 [A].  Is that loaded, or unloaded (I hope that's loaded)?  Mine, with a 3 hp Marathon, draws 3.6A at 237V with no load, as measured with my modest instruments.  Determining when the motor is outputting the full 3 hp when cutting wood for the sake of measuring current draw would be impossible, so any loaded current measurements would be an estimate at best.

   I've megged the motor, it checks out.  Megger testing will verify the integrity of insulation between windings, and between winding and ground (as I understand it), but I don't know how it would shorted (i.e. shortened) windings.  May I suggest you check the DC resistance of the windings.  Mine measures 0.8-0.9 ohms, at the motor leads.  If you have a dual voltage motor (mine is 230V only, and not reversible), it would measure about 1/4 as much when wired for 115V as compared to 230V.  You can't really use the DC resistance for anything other than to check against other motors of the same make and model, looking for shorted windings or miswiring.  If the start/run winding, (it's both if the motor has 2 capacitors; only the start capacitor is removed from the circuit as the motor approaches run speed) is separate, as it would be if the motor is reversible, then I believe you will get infinite resistance once the capacitors are charged by the ohmmeter.  Some measurable and unchanging resistance across the start windings would suggest a shorted or defective capacitor or two.  I measure 2-3k ohms initially on an analog ohmmeter, increasing steadily as the capacitors charge. 

   From your description of humming, then tripping, it sounds like there is a start and/or run capacitor problem, or it's in the centrifugal switch.  The capacitor(s) or windings sound more likely, since it happens when the motor heats, unless the centrifugal switch isn't opening after start and overheating the start capacitor (they're not usually continuous duty, like run capacitors).  If you suspect the problem is in the motor, a motor shop can test the windings and capacitors easily.  Or just holler at Delta until they give you a new one.

   I hope some of this diatribe helps.  If I can think of anything else, I'll post it.Be seeing you...

1. 
   purswell | Oct 13, 2002 03:52am | #14

   I don't have any line/ voltage sag when its running, It is at 12.6 amps loaded or free- I haven't put anything bigger than 8/4 oak through, but it doesn't waver more than .2 amps.  I megged it because I thought-as you point out- that the insulation may have a small hole that start up current finds a way through- Like I say, if it starts, its fine.  I am hoping not to have to take anything apart, but from what I can tell, I've checked everything I can without getting in its belly.  I really don't relish the thought of sending it back either.

2. 
   TKanzler | Oct 13, 2002 04:14am | #15

   At 12.6A unloaded, your motor is experiencing technical difficulties.  As I said above, my Marathon draws 3.6A unloaded.  I don't know what motor you have, but the 3 hp Baldor for the Unisaw (complete with special mounting) draws 5.9A no-load.  Go here to see -

   http://www.baldor.com/products/perfdata.asp?1=1&catalog=WWL3606&product=AC+Motors&family=General+Purpose%7Cvw%5FACMotors%5FGeneralPurpose

   Here's a picture of that motor, in case your interested -

   http://www.baldor.com/products/detail.asp?1=1&catalog=WWL3606&product=AC+Motors&family=General+Purpose%7Cvw%5FACMotors%5FGeneralPurpose

   It sounds like the centrifugal start switch isn't opening, to me.  Just an educated guess.  Tell Delta that it's drawing 12+ amps no-load, and they should send you a new motor.  I don't see any way around taking the motor out, but at least it's a pretty easy job on a Unisaw. 

   On second thought, before disassembling the motor, are you sure it and the arbor spin freely?  Belts not cranked up impossibly tight (they're supposed to run relatively loosely), nothing binding?  Be seeing you...

3. 
   jeffn7 | Oct 13, 2002 05:43am | #16

   the calibration plate on my unisaw motor lists 12.6 amps... is that a loaded number?

4. 
   TKanzler | Oct 13, 2002 06:35am | #17

   At first I thought you meant "loaded" as in Sears 6.5 hp air compressor that runs all day on a single "D" cell. 

   Yes, that's Full Load Amps, or FLA.  Mine says 12.4 A.  It's also a reasonable, if pretty good, number.  Here's a different Baldor I grabbed at random, drawing 12.5 amps at 230V continuous.

   http://www.baldor.com/products/specs.asp?1=1&catalog=UCLE153&product=AC+Motors&family=Farm+Duty%7Cvw%5FACMotors%5FFarmDuty

   p.s.  I keep citing Baldor because they have pretty good on-line technical data so I can post links, and people seem to like their motors.  Interestingly, my favorite industrial hydraulics vendor uses Baldor exclusively in power units because they can get their small motors (<100 hp) cheaper than any other brand.  Go figure.Be seeing you...

2. 
   DouglasABaker | Oct 14, 2002 07:43pm | #18

   Rich,

   <rant on>

   There are a couple of issues at hand here:1.  Folks don't read the whole post to get all the information before responding, and 2.  We occasionally get "answers" that have no basis in fact (or even fiction on occasion)

   I am not suggesting "narrow, dry, technical recitations from tech manuals", I'm simply suggesting that we answer the question asked.  If you can't, simply tell people up front.

   As for "No one has to read anything he or she wants to ignore", I would question how exactly you propose this be accomplished.  Since folks tend not to say "I don't know, but..." at the beginning, you have to read a post to know it is useless - so No, I can't just ignore it, otherwise I might miss the ones that actually address the issue.

   This isn't burying your head, this is trying to find a way to weed the valuable from value-less.

   <rant off>

   So here's my proposal for everyone:

   If you aren't going to answer the question that has been asked, simply start your reply with "I don't know, but..."  The information will still be out there, but for others who simply want an answer to the question asked, they know to skip to the next one....

   d-

1. 
   Scarecrow | Oct 16, 2002 04:00pm | #19

   If the data plate rates your motor at 12.6amps that is it's currant draw in a worse case scenario or max before failure.  Your motor should run something well below that.