Circuit design for 10.5 amp 230V 2HP motor @ 3450rpm

I would suggest you get a qualified electrician in to wire up these items, it is evident you don't have a clue.

Heck, just tell him straight out that he can't use that motor. It's unlikely in the extreme that his home provides the 3-phase power he needs to drive that motor. That's what his electrician is going to tell him.

John Perry

On Tue, 18 Jul 2006 23:10:47 -0400, John Perry wrote in Msg.

Depends on where he lives. In Europe, 3-phase 400V lines go into every home. robert

The only possibility for you, will be a 3 phase inverter unit. The motor you have, is industrial, and built to run on 3 phase. it sounds as if it can be wired for either star, or delta configurations (hence both ends of each winding are available). A normal house supply, will only be single phase, so three choices exist. First to pay to have 3phase electricity supplied to your house (expensive), or buy an inverter unit, which generates a 'synthetic' 3phase from your single phase supply. The latter in general, is significantly cheaper than getting 3phase power, and has the added advantage that most units will include options for soft start, and variable speed. The third option is to substitute a single phase motor. Look at:

The SV022iC5-1F, would probably be the unit for your motor. However _seriously_, if you have to ask the question, you do not have the experience, to wire such a unit safely, and if you value your own, and your families lives, you should consider getting a professional to set this up for you.

Best Wishes

A motor starter (controller) should be used with any motor you want to protect from overload, and the overload trip elements in it must be sized to the protected motor. Look for a table of trip element number vs full load amps (FLA) and buy the right trip elements new.

Perhaps different voltage rating between coil and contacts? Try the mfgr's web site?

L1, L2 and L3 refer to line in of three phase power, T1 etc are the motor terminal connections for a 3 phase motor. If these are on the wiring diagram for your controller and you have a single phase motor, no problem, run your two hots in L1 and L3 and out T1 and T3, after verifying that L1 - T1 and L3 - T3 are the circuits which contain the overload elements. If these designations are on your motor then it is a three phase motor and you need a phase converter. There is a good rotary phase converter design posted to the rec.crafts.metalworking newsgroup "dropbox", someone on that NG could tell you where it is.

The difference between neutral and ground, which are joined only in your panel, is that the neutral normally carries load current and the ground *only* carries fault current in the event of a short circuit to ground. Unless you need 120 V for the controller coil you should not even need to run a neutral to a 240 V motor circuit, but the ground (AKA safety ground) is always mandatory and must be connected solidly to all metal enclosures of energised equipment.

While I have no problem with DIY electrical work, I very strongly recommend you have your work inspected by a licensed electrical underwriter (inspector), and that you line up the inspector and discuss the job with him before you start.

The motor data indicates that it was made for the US market, and he is posting from a US based ISP.

--
Service to my country? Been there, Done that, and I\'ve got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

OK Gentlemen, first it would appear that this request for assitance is misplaced in this advanced a forum. Second, it IS NOT a 3 phase motor. It is a 1 phase motor - and I am very clear about the difference. I asked about the L3 as an abstract type question not specifically tied to my situation.

And at the risk of displaying obvious umbrage at some of the remarks, I most definitely do have a clue about AC - at least the 120/240V variety common to my home. I simply need some additional information to fill out the gaps.

Should it help establish my level of understanding, I have completely rewired and redesigned the circuits in my 3 bay garage to make sense for the machines and power needs I employ, including a 'pony box" with a 60 amp 240V draw off the main box so I don't have to run wire so far. I've also succesfully installed a ten circuit gas generator interface for when the power goes out (which happens 4 to 5 times a year from nasty windstorms).

I won't pretend I completely understand 3 phase - but I can tell you that I don't have it in my home and I am not interested in using a 3 phase motor, dirt cheap though they may be, as I have a perfectly good

2HP motor.

So perhaps we could start over.

Thanx. TSL

Another Wally wrote:

I second that. I'm an electronics engineer with a master's degree, 15 years of experience, 5 years of electrical installation experience before that, etc., etc. -- and if I did work of that magnitude in my home I'd happily pay to have a second pair of eyes take a look at it before I fired it up.

Most insurance companies will deny coverage (or at least try) if home-done, uninspected electrical work catches fire. Many will try to deny coverage if an arsonist starts a fire on the outside wall of a building housing such work. Getting the thing inspected in small potatoes.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google?  See http://cfaj.freeshell.org/google/

"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html

OK, now were getting somewhere. Thank you Mr Walpert.

I am clear about the difference between the ground and nuetral in general terms. What I am unclear about is why a 240V motor (which is also on my compressor) does not need the nuetral? This is one of the gaps in my understanding. It bugged me when I hooked up my compressor but i just let it go. With what I am doing now, I'd really like to understand why 240V seems to change the whole playing field and drops the nuetral.

My Dayton 1 PHASE 2HP 115/230V, 21amp/11.5amp, 3450rpm motor on a nema H56 frame is sealed so as to not allow in wood dust and chips and debris and is specific for my application. I am clear that I have the option of either wiring it as 115 or 230, but the 10.5 amps running through 2 hot lines is an easier and smarter move for my situation than

21 amps through one hot wire. I have a 240V dual 15amp breaker in my pony box that awaits my wiring. I will take power from it down to the control panel and run it through an AB 2 position maintained key switch with two contact blocks on it (a 120 line going to each contact block) and then through a 2 position estop button on the panel, also with two contact blocks. Then it will run to a stud mouted outlet with a twist/lock receptical. A ten gauge industrial sheathed cord with the male plug then runs to another identical estop positioned on the saw itself, then to a 240V foot switch, and then to the motor. But as I started getting deeper into the AB world, I bumped into these motor starters and as far as I can tell, they are used on 1 phase motors in some instances. As best I can tell, they help the motor ease into full rpm and give it "cleaner" power and better circuit protection - which is supposed to increase motor life. Thus my question about using a motor starter setup between the control panel and the wall outlet. But it may just be overkill and hubris - I don't know. I need help understanding the pros/cons.

While I thank you for your concern, I work at an establishment with a full time maintanence crew; one of which is a certified elctrician. I am very clear about the code in my area and have followed it to the letter; including distances from outer stud to romex feed holes, proper gauge romex and proper amperage outlets etc.. My 3 bay garage is almost totally bare rafters and studs and thus it is very simple to run romex along the top of the rafters and staple them in along other existing wires. In the cases when I dropped a wire to one of the 2 small finished walls (code mandated with fireproof drywall where garage meets house) I start conduit in the rafters and route it down onto the drywall. I am a systems geek by profession and extremely meticulous about safety in all my endeavors; right down to safety glasses and ear protection when I just mow the lawn.

As to the transformer versus full voltage, I entertained that the voltage may be different. But when they attatch an 800T-XA contact block that will handle up to 600V (though only at 15 amps) and the same contact blocks are used on both, and the operators themselves show no design difference whatsoever, I began to wonder whether it was just a case of categorization to satisfy NEMA or that other standard that escapes me at the moment. It may only be something employed with the illuminated switches. But the illumination contact blocks for the 120V full voltage and transformer voltage appear identical in both style and design #.

Again, thank you for your time. TSL

Glen Walpert wrote:

OK, OK, I get it. I'll have it inspected. You had me @ the insurance thing . . .

TSL

Tim Wescott wrote:

Robert Latest wrote

No they bloody don't! European electricity supply undertakings are very reluctant indeed to supply 3 phase power to anywhere other than industrial and commercial users, where there is no alternative. In fact you may as well say that domestic customers are limited to 230v single phase.

However 415v three phase lines are buried in the street, and houses are supplied from phase + neutral.

Perhaps a DC example would help. View in fixed font

+----Hot-----+-------------+ + | | | ---------- ------- | |Battery 6V| |Bulb 6V| | ---------- ------- | | | -------- +----nnnn----+ |Bulb 12V| + | | -------- ---------- ------- | |Battery 6V| |Bulb 6V| | ---------- ------- | | | | +----Hot-----+-------------+

For the purpose of the analogy, call the wire labeled nnnn "Neutral". It is easy to see why it is needed - it makes both 6V bulbs "happy". They get 6 volts each, and will continue to work if the other 6V bulb burns out. They will both glow at the proper level, even if the top one draws

7 amps and the bottom one draws 300 mA.

Eliminate the "neutral" wire and those 6 volt bulbs may have a problem. For example, if there was no neutral and the top one tried to draw 7 amps, it would have to draw it through the bottom bulb. If that bulb was rated only for 300 mA, it would burn out.

The 12 volt bulb doesn't need the neutral. It gets the proper voltage from the two wires marked "hot" with no need for an additional current path.

In your resisdence, the incoming 240 volts comes off a center tapped transformer, anologous to the two batteries above. Your 120 volt appliances are analogous to the 6V bulbs. Your

240 volt motor is analagous to the 12 volt bulb.

Ed

OK great, we have established 3 phase power is not a European standard. But this is moot to my issues.

I've still got 2 of my questions unanswered. Should I ask them in a different forum than design? It's not that I don't appreciate the involvment and time expended thus far, it's just that I need some answers. The electrician at my work is Italian born and speaks English with a classic, heavy Italian accent. He and I get along great. But when I ask these particular questions, I don't seem to be communicating well because he looks at me with some confusion - plus he talks fast when he gets going. I'm not going to have an inspector come out in the very sprawled and busy county I live in just so I can get some questions answered. I would rather wait until I get it all done and respect his time.

So I still need help. If this is the wrong venue, please point me to the correct one Thanx. TSL

FANTASTIC - thanx Ed. One down. Two more to go - care to take a whack at my motor starter & brake issue, Ed?

TSL

Well, I don't have much to say about it. As I see it, you've done the "good stuff" - brought a 60 amp line to the location with a 20 amp circuit for the saw. I think the additional electrical work (motor starter & brake) beyond that is pointless. (I suppose that if it's a new motor, the manufacturer would recommend starting and braking circuitry as needed.)

Ed

In a nutshell, the neutral is the center-tap of the 240V transformer that feeds your house, so you get 120 to neutral on the black, and

120 to neutral on the red, and 240 from black to red. When your device is using the whole 240, the neutral is irrelevant - when you use a 120V item, all its return current flows through the neutral, which is why people like to balance the loads on the two legs (which some people erroneously call "phases" - there's only the one phase, but the 240 is center-tapped) just because it's nice to minimize the neutral current - it evens out the load on the halves of the secondary of the pole pig.

Maybe visualize a loop or three... ;-)

Hope This Helps! Rich

I don't know the exact rules in the US, but my cousin's farm has had

3-phase since I can remember, and I somehow think that if you paid for all of the wiring, transformers, work, etc, the power company would be happy to string any kind of power you want to your house. :-)

If I'm wrong and there's some kind of rule against it, I'd be happy to be enlightened, so to speak. ;-)

Cheers! Rich

On Wed, 19 Jul 2006 09:08:44 -0700, TSL top-posted: [some snit]

I don't understand the problem - if you already know that stuff, what are the questions for?

But just because I'm such a smartass, here ya go:

Yes, and I wouldn't try to use an electric brake on a motor that old without talking to the guy who's selling the electric brake, and maybe having the motor checked out by a motor shop.

You'll have to ask the guy who's selling you the switch.

This is the generic "line - terminal" question which has been answered already.

So, what's the problem?

Thanks, Rich

He doesn't have a 3-phase motor. He's got a 240V, single-phase motor. That question was just a red herring.

Cheers! Rich