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Generac Generators (SEARS, etc.)

Sears Generator 115 - 115/230 Volt Switch


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  #1  
Old 02-22-2018, 07:21:59 PM
teslaelectric teslaelectric is offline
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Default Sears Generator 115 - 115/230 Volt Switch

Hello all, first time posting. I recently acquired an old Sears 3000 watt generator, model 580.320212 with electric start. The Tecumseh engine runs great after replacing the carburetor and fuel lines. Unfortunately, the prior owner hacked up the wiring in the generator junction box and removed the switch which changes the generator output from 115 volts to 115/230 volts. I'm assuming it broke and was removed, as the unit still puts out 115 volts. However the 230 v plug has no wires to it and there are loose conductors floating around in the box. I'm in need of a schematic for that particular unit or a photograph of the wiring in the box to try and sort it out. I tried searching the web and contacting Sears but to no avail. Any help would be appreciated, thank you!
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Old 02-26-2018, 10:30:35 PM
tinkerman2012 tinkerman2012 is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

Not for this specific machine but here is a drawing which might assist. You need a four pole double through switch.
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Old 02-26-2018, 10:37:05 PM
tinkerman2012 tinkerman2012 is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

double *throw switch
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Old 02-26-2018, 11:48:14 PM
teslaelectric teslaelectric is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

Thank you for the drawing! I will order the proper switch asap

Unfortunately all my wires are black with some labelled with number tags. The prior owner has 10 and 44 wired to the neutral of the plugs and 20 to the hot side of the 115 volt plugs. Number 22 is not connected but has 115 volts with respect to 20. Do these numbers ring a bell to anyone with a similar machine, i.e. is any of this correct?
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Old 02-27-2018, 12:51:59 PM
Vanman Vanman is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

I believe that this can also be accomplished with a two pole, double throw switch. Will have to check.
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Old 02-27-2018, 11:43:52 PM
tinkerman2012 tinkerman2012 is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

all those wires 10, 44, 20, 22 directly off the windings?

The numbers don't ring a bell with me but there could be a numbering convention. Someone else may chime in here.

What I would do is find the four leads from the windings. Label one winding T1 and T2. Tie T2 to one of the leads from the second winding. Now read the voltage from T1 to the open end of the second winding. If you get 230 volts across the two windings you have them in series and polarities correct. If you don't, reverse the leads from the second winding and try again. Once you have 230 volts you can go ahead and label the second winding T3 and T4. (T2 and T3 will be joined together). Once that is sorted out you can proceed with the switch wiring. If Vanman has a circuit for two pole double throw switch use his. It should be easier to come by and be cheaper. I've only run across the four pole connection.
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Old 02-28-2018, 01:23:14 AM
Vanman Vanman is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

While those numbers sound vaguely familiar, I also do not know what convention they might follow. The method suggested by tinkerman will get them sorted out for sure though.

I looked into the switching some more. The two pole switch arrangement I had been thinking of was for a somewhat similar, yet different project. Two 12 volt batteries switchable between a 12 or 24 volt output.

It will work for your generator, but the 115 volt, full capacity receptacle would remain energized while the switch is set to 230. You'd have to remember not to overload it, otherwise the breaker would trip.

Set to 115 volts, the one side of the 230 volt socket would remain energized. A non issue, really.

On the other hand, a three pole switch could be arranged to de-energize both the 230 volt socket when running 115 only, and the full capacity 115 volt socket when set to 230. The regular 115 volt sockets would work at all times, as they should. The switch would need to be rated for the full 115 volt only current.

Last edited by Vanman; 02-28-2018 at 02:31:52 AM.
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Old 02-28-2018, 01:40:51 AM
Vanman Vanman is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

Here's a diagram for a three pole switch. The nine dots represent the switch terminals, the three in the center with "C" next to them being the common terminals. Throw the switch to the left for 115 volt, two wire operation, right for 115/230 three wire.

For simplicity, not shown are any less than full capacity 115 volt sockets (that would work in both switch positions), a neutral for the 230 volt socket, or a circuit breaker. All are easily added.

To use a more readily available two pole switch, merely omit the lower pole on the diagram, and permanently connect the three wires. That switch would also need only be rated for the 230 volt full load current.
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Last edited by Vanman; 02-28-2018 at 02:33:08 AM.
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Old 02-28-2018, 02:43:45 AM
Vanman Vanman is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

Quote:
Originally Posted by teslaelectric View Post
Thank you for the drawing! I will order the proper switch asap

Unfortunately all my wires are black with some labelled with number tags. The prior owner has 10 and 44 wired to the neutral of the plugs and 20 to the hot side of the 115 volt plugs. Number 22 is not connected but has 115 volts with respect to 20. Do these numbers ring a bell to anyone with a similar machine, i.e. is any of this correct?
To clarify your observations:

10 and 44 are wired to the neutral on the plugs. Are 10 and 44 then wired together as well?

You read 115 volts between 20 and 22. And presumably the receptacle also reads 115, between 20 and 10/44?

How about between 22 and 10/44?
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Old 03-01-2018, 01:12:36 AM
teslaelectric teslaelectric is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

Yes, 10 and 44 are wired together to the neutral of the 115 v plugs. They both go to the generator head. On the hot side of the plugs are two wires also, 20 and another unlabeled wire. 20 goes to the regulator, the unlabelled to the generator head. 22, the unknown, comes from the generator head and goes nowhere. When running, I get 115 volts from 20/unknown to 10/44, and 115 volts from 20 to 22. No volts between 10/44 and 22. My current guess is that the two 115 volt coils are in parallel across the plugs and that by reconfiguring them I can get 220. I will run the unit this weekend, take some more measurements and let you know.

Also, the regulator is a transformer style gadget on the side that is typical of the old Sears units. It has 5 wires coming from it. I'm curious on how it interacts with the rest of the circuit. I'm not familiar with them, any information on that would be appreciated too!

Thank you again to all you folks for your help, especially the diagrams! I have an electrical engineering background and love old iron but old generators are a new hobby for me!

Vanman, your 3 pole arrangement would be good enough for me, I will work on identifying the two output coils. Thank you. At this point I want to fully understand how the regulator interacts as well before I plan how I'm going to rewire it. I understand the principal behind regulators, just not how it's implemented on a 220 generator with multiple windings.
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Old 03-01-2018, 03:13:25 PM
Vanman Vanman is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

While I cannot say with certainty, my guess is that the transformer is part of a circuit to increase excitation as load increases in order to keep output voltage constant. I have a Kohler with this arrangement. It is quite clever, the embodiment of elegant simplicity.

Frequently, incorrectly referred to as transformer regulated, a better term is transformer compounded. It does not regulate, nor does it need to. It allows an AC generator to function exactly as a compound wound DC generator.

But we may be getting ahead of ourselves here. Will have to follow the leads, see what they connect to, then go from there to know for certain what the transformer's function is. Hopefully the leads are still connected at least somewhat correctly.
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Old 03-02-2018, 04:47:39 PM
teslaelectric teslaelectric is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

Update: With the poor weather here I have not been able to run the unit, but I took detailed notes of what was left of the controller and took it apart to trace everything out. I also found that what I previously thought was the mystery wire actually has a small number printed on it, as do all from the transformer. Here goes:

1st set of wires: Engine controls. 3 wires, 90, 92, 94, all to the start/run/off toggle. This works fine.

2nd set of wires: Generator head. 7 wires. 1,2, & 4 wired through (soldered?) to the transformer, 10, 22, & 44 to the plugs, and 6 to the fuse for the battery charger.

3rd set of wires: Transformer. 1,2,& 4 to the generator head, 3 & 5 to the plugs.

With a multimeter, I determined that 3 & 22 are coil #1 and 5 & 44 are coil #2. When I run the generator again, I should get 115 v from each and 220 in series when phased correctly. 10 is still a mystery, as it shows high resistance to 3 & 22 and nothing else.

Vanman, thank you again for your explanation of the transformer, I did some further research and now understand how it keeps the output constant.

It's all starting to make sense now!
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Old 03-06-2018, 10:23:58 PM
teslaelectric teslaelectric is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

Progress...

I was able to run the generator briefly last weekend, but still no voltage. Not even the 115 I had last time. Hmm. So, I took apart the back of the generator head and went at it again with the multimeter and found a few things:

The three spliced through wires from the generator head to the transformer have additional labels, hiding under the cloth insulators. Coil #1 is 33 and 44, with 33 connected to 4 on the transformer, and coil # 2 is 11 and 22, with 11 connected to 1 on the transformer.

Wire 10 is connected to one of the AC terminals of the diode rectifier, with the other end connected to the transformer via wire 2. This feeds the exciter power to the brushes. 2 is terminated in the transformer to 1 and 3, on the coil # 1 circuit.

So, if I connect 10 to 22, the exciter circuit will be complete through the transformer, which supplies power to the brushes. An increasing current pulled through the transformer will increase the voltage on wire 2, causing the DC rotor voltage to increase, keeping up with the load. It all makes sense now.

Hopefully I'll be making power soon!
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Old 03-07-2018, 12:09:44 AM
Vanman Vanman is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

Yes, making sense now. Good sleuthing!

Incidentally, I have a similar set, branded Milwaukee, and painted red, but probably the same manufacturer. My dad bought it in the mid '60's for his business. I want to say that it's 1750 watt, 115 volt only. Powered by a 4 hp Briggs. Also has the transformer.
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Old 03-26-2018, 07:50:33 PM
teslaelectric teslaelectric is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

Finally got some good weather to work on the generator with success! The no output problem was solved by cleaning the slip rings which were filthy from sitting outside for many years. With good brush contact and wire 10 connected to 22, I finally had 120 volts on 3 & 22 and 5 & 44. Connecting 3 and 44 puts the two in series for 240 volts between 5 and 22. Yay!

I drew a quick schematic of what I have so far to help anyone out there with a similar generator. I'm not 100% sure, but the wiring convention may hold true for other Sears/Craftsman units of the same vintage.

It will be a simple matter now to wire a series/parallel switch and complete this project!
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Old 03-26-2018, 10:14:29 PM
Jim Tremble Jim Tremble is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

[QUOTE=teslaelectric;1464127]Hello all, first time posting. I recently acquired an old Sears 3000 watt generator, model 580.320212 with electric start.

Your generator is a • 580 Goldstar / Generac Corporation
/www.generac.com/
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Old 03-31-2018, 01:52:03 PM
teslaelectric teslaelectric is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

Installed the switch and finished up the wiring today. After some research I came up with a schematic for a series-parallel switch using a DPDT toggle and was able to hook everything up after two trips to the hardware store to get quick connect terminals In position 1 (115 volt only) both coils are paralleled to the hi amp 115 volt plug (26 amps). In position 2 (115/230 volt), one coil goes to the two rear plugs (13 amps), the other to the hi amp plug (13 amps), and both are in series to the 230 volt plug (13 amps shared with the two others). Technically you could overload the hi amp plug in this position but I'm not powering anything heavy with this and I can live with that as long as I know. I also installed a new rear bearing in it, a Peer 99502 C3. The old one was worn and tired.

Anyway, thank you to everyone who helped Jenny get up and back on her feet again, she now runs like she's supposed to! On to the next project!
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Old 04-16-2019, 05:10:55 PM
Rodney Dawn Rodney Dawn is offline
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Default Re: Sears Generator 115 - 115/230 Volt Switch

I have exactly the same generator end but with a briggs engine on it I picked up cheap on CL. the switch simply ''rewires'' the output to either give full wattage at 120v by paralelling the windings, or providing 120/240 by connecting the windings to the outlets individually. not sure the hp rating of the tecumseh model, but the briggs model the engine is a bit overpowered (8hp for only 3000w) so you can set your hz no load at closer to spec. (61hz no load gives 60hz half load and 59hz full load) whereas the usual method when hp and kw is matched is 62hz no load/60hz half load/58hz full load. the only downside is you have to watch your load more as the engine has more than enough power to smoke the windings before it would lug down enough to stall out.

Should be a solid runner once you get it sorted out. these older generacs are built considerably better than what Generac sells these days. the weak link will be the valvetrain problems inherant with tecumseh engines (probably why they made the same generator with briggs engines too). the generator head is a brush type and the 3000w rating is continuous duty. surge watts are not listed but if the engine is 8hp like on the briggs version sould be around 4000 (momentary for starting motor loads)

fill the crankcase first, then fill the oil tank (if it has one) that's the proper method.

not much that can be done about the inherant valvetrain issue. moly in the oil might help to prolong it, but the valve retainers are still going to grenade sooner than most flathead engines. the retainers are relatively easy to replace if you have a spring compressor tool, so its not a huge problem, just something to be aware of.
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