New DC motor blowing fuses

[Jacob Larsen]

Last night, I purchased a new Delta 50-760 through an Amazon price match from a local dealer. I brought it home, assembled it, and plugged it into the fused, dedicated 20A circuit I use for my TS with identical motor ratings (1.5 HP, 15A @120V). When I turned it on, the motor started to spin, then blew the fuse in the circuit. Since I had extra fuses, I decided to try it a second time. Same thing happened. Initially, I was thinking I needed to convert it to 240V (which I intend to do in the future), but noticed that the two blown fuses had their windows blackened. The fuse package said that indicates a short circuit instead of a overloaded circuit. Was this simply an overload, or could there be a problem with the DC motor?

Any assistance would be greatly appreciated!

[John Kempkes]

It could be a problem with the capacitor start. If you can return it, do so.

[Jeff Horton]

Doesn't sound right but I was told that fuses trip faster than breakers. So I would try a time delay fuse and see if that fixed it. If not I would call Delta. because you (most likely) have a problem.

[Don Baer]

Is there any ducting hooked up to the blower ? If not then try it with come ducting hooked up. The lower doesn't like sucking directly in.

[Rick Christopherson]

Don is on the right track, in that most people don't realize that a dust collector is under the greatest load when it is clean or completely disconnected from the ducting. When the dust collector (ducting) is clogged, the impeller is operating in a vacuum and there is very little resistance.

[Jacob Larsen]

Thanks for the replies!

I have the 4" Y plus the 6' hose attached to the DC that came with the machine. The motor only starts to turn when it blows the fuse. It never gets up to speed.

[Kent Fitzgerald]

First things first - I don't want to cause offense, but some things are too important not to mention. Are you sure it's really a 20A circuit (i.e., 12 gauge wiring)? Fuse systems make me nervous, because it's way too easy to create a serious hazard by substituting a 20 or 30A fuse on what should be a 15A circuit. Unless you've physically verified the wire size, it's always best to assume that a circuit shoud be fused at 15A.

Even if it is a legitimate 20A circuit, fuse blowing isn't surprising. DCs draw a lot of current on startup as a result of the inertia of the heavy impeller. As others have mentioned, unresticted airflow will make things worse. You might want to try completely blocking the DC inlet (no, it won't hurt the DC).

Here's what Delta will probably tell you if you call them (4th item down): http://www.deltamachinery.com/index.asp?e=144&p=465
They refer to the 50-850, but it applies to other DCs as well.

CAUTION: Delta's response could be taken to imply that you can swap to a 30A breaker/fuse without upgrading the wiring, which creates exactly the problem I described above. A 30A circuit requires 10 gauge wiring. If you're going to install a new circuit, you might as well go to 240V.

[Kent Fitzgerald]

Oh, yeah, the blackened fuse window is a bit of a red herring. Blackened just means the fuse blew rapidly (which you aready knew) - could be either a short or a heavy overload.

[Andy Sowers]

I agree with John... could be the start capacitor.

I recently bought a very used 50-850 from a local guy who was selling off most of his WW machinery. He sold it to me for $20 because the "motor had blown."

However, when I got it home I discovered it was just the start capacitor which had gone bad. The motor would try to spin up, but would kick out the breaker after about a half second. I determined that the cap was bad by taking an ordinary 9V battery and tried to charge it up. Mine wouldn't hold a charge.

Its an easy check (and cheap replacement)... if its bad, I agree return the DC for an exchange since yours is brand new...

[Rick Christopherson]

Thanks for the replies!

I have the 4" Y plus the 6' hose attached to the DC that came with the machine. The motor only starts to turn when it blows the fuse. It never gets up to speed.

By saying the motor just starts to turn, is this 1/2 to 1 second, or is it a couple of seconds?

If it is 1/2-1 second, then the problem is the fast-blow fuse. If this is taking more than a couple of seconds, then the motor is not getting up to speed as quick as it should.

If the motor is slow getting up to speed:

• Make sure you are not using an extension cord to give it power. If an extension cord is necessary, make sure it is at least 12 guage, and the shortest possible length.
• Check the motor junction box (on the side of the motor) to verify that the motor was not already configured for 240 volts.
• If the house wiring is 14 guage and someone just threw in a 20-amp fuse, then you could be getting enough voltage drop to slow the motor startup.
• If you can eliminate house wiring problems, then you've got a bad motor.

[Cliff Rohrabacher]

Put a penny in the fuse box.

Since the 1960- 60s with people lighting their houses on fire wiht copper pennies the Mint decided to change the penny from copper to Zink. So all pennies are now made of zink with a few millionths inch electro plate of copper.

Now all pennies are rated to 20 amps at 350 VDC at 60% RH.
It is imprinted on each penny on the left hand side of Lincoln's head. Ya gotta turn it over to se the rating specs.

DISCLAMER:
I in no way endorse the installation of pennies in fuseboxes.
Improper installation of pennies in any application for which they were not intended may cause headaches, nausia, male lactation, and death fom housefire.


Try the motor on another circuit. It it is still a problem take it back.

[Jacob Larsen]

First things first - I don't want to cause offense, but some things are too important not to mention. Are you sure it's really a 20A circuit (i.e., 12 gauge wiring)? Fuse systems make me nervous, because it's way too easy to create a serious hazard by substituting a 20 or 30A fuse on what should be a 15A circuit. Unless you've physically verified the wire size, it's always best to assume that a circuit shoud be fused at 15A.

Even if it is a legitimate 20A circuit, fuse blowing isn't surprising. DCs draw a lot of current on startup as a result of the inertia of the heavy impeller. As others have mentioned, unresticted airflow will make things worse. You might want to try completely blocking the DC inlet (no, it won't hurt the DC).

Here's what Delta will probably tell you if you call them (4th item down): http://www.deltamachinery.com/index.asp?e=144&p=465
They refer to the 50-850, but it applies to other DCs as well.

CAUTION: Delta's response could be taken to imply that you can swap to a 30A breaker/fuse without upgrading the wiring, which creates exactly the problem I described above. A 30A circuit requires 10 gauge wiring. If you're going to install a new circuit, you might as well go to 240V.

Thanks again for the input. Just got home from work for the weekend. I went to double-check, and the wiring from the fuse box is 12ga. I have a basic knowledge of house wiring as well as general electrical circuits from college. When I set up the circuit for the table saw, I was trying to figure out how to add it to the already full fuse box when I discovered a 20A fuse labeled as the "Ironing Outlet". It turns out that this was the outlet hanging over our washer/dryer. With the panel off the box, I confirmed that this was the only thing connected and ran that over to the saw.

To answer other issues, the motor only runs for 1/2 to 1 sec. As it cycles down after blowing the fuse, I can hear a click that I have heard before when shutting down induction motors. I do have it on an extension cord, but it was the 12ga cord I use for the saw. The thought had crossed my mind that the motor was wired wrong, or that there was a loose wire but I checked and everything looks correct.

After reading Delta's website, and from the info here, I think I will try to set up a 240V circuit for the DC. Since 240V cuts the amperage in half, do you think it would handle both the saw and the DC on the same circuit? (assuming both do not start up at the same time)

Thanks for all the help. I have been lurking around this site for a while now and the opinions of different woodworking equipment have come in handy for some of my purchases.

[Jacob Larsen]

One more thing to add. These are the time-delay fuses. Type SL "for circuits containing motor driven tools or appliances." They are also the tamper-proof type as you cannot screw a 20A into a 15A socket.

[Rick Christopherson]

Because both motors are 1-1/2 hp, yes, you should be able to run them both from the same 240 volt, 20 amp circuit.