Wiring a Jet DC1100 for 230v

[John K Jordan]

...Any modern North American wiring is 120/240. ...Edison...

In the defense of motor discussions the US standard for name plates for single phase motors is 115 (or 230) volts. I checked several in my shop and they were compliant.

Although the target current supply voltage standard is 120/240 nominal, the allowable supply voltage is 114 to 126 (plus or minus 5%). That, BTW, is the Range A described in ANSI-C84.1-2011. Range B values are 110 to 127 volts.

Historically, supply voltage has been 110, 115, and even 117 volts in different places.

When someone discusses AC power I personally read 110, 115, and 120 as identical in my head. What's a few volts among physical and forum friends. When someone says 110v I know what they mean. They say 120v I know what they mean. I look at it this way - in the home and shop we are using "110v" not as a value but as a name (label) to describe a thing to another person - the thing is the power we get from a typical receptacle anywhere. We seldom measure it with a meter and use it as an actual value - we don't care if it is really 110v or 118v or 122v.

BTW, if Edison had had his way, the electrical power grid would be DC instead of AC. The War of Currents between Edison and Tesla (and later, Westinghouse) was eventually resolved when it was demonstrated that high voltage AC was far more efficient to send over long distances. And AC is far easier to convert to any other voltage (simple transformer) AND cheap/easy to convert to DC where needed (simple rectifier and capacitor).

Some references:

American National Standard for Electric Power Systems and Equipment – Voltage Ratings (60 Hertz)
ANSI C84.1 – 2011
published by National Electrical Manufacturers Association (NEMA).

Pacific Gas and Electric
Voltage Tolerance Boundary

UNITED STATES DEPARTMENT OF AGRICULTURE
Rural Utilities Service
BULLETIN 1724D-113
SUBJECT: Voltage Levels on Rural Electric Distribution Systems

JKJ

[Andre Spenard]

Thanks for posting the diagrams.
I just acquired an older DC1182 that was also prewired for 115 (110, 115, 120 per an earlier post).
There is no diagram in the switch box, but there are two additional wires not shown in the DC1100 pic.
I see the wiring diagram for 230V shows the pre-'96 3-wire configuration.
I had already run 12-3 to the location to a 4-wire socket and made up a matching 4-prong pigtail.

I have two questions -
1. What to do with the isolated neutral? Should it go to the middle lug as would be typical?
2. See the two additional wires? The red was clamped with 1&2, the black with 3&4. These must have been eliminated with the newer model.
Should they go 1&4 on the 120V legs, or with 2&3 on what I take to be the neutral lug?

Thanks
DC1182.jpg

[Bill Dufour]

The reversed neutral and hot leads is only an issue if you use a single pole switch. For 120 only the hot leads need to be switched. For 240 both hots need to be broken by the switch. On 120 volts no reason not to switch both hot and neutral wires if the switch is two pole already.
Never ever switch the ground lead.
Bil lD

[Robert Engel]

The question I have is why change. The motor will have exactly the same power on either voltage as long as the wiring in the wall is adequate.

Exactly....

[Billy Merrill]

It is always best to run a supply of 240V instead of 120V if it is a dual voltage motor. With 240V, you will have a little more torque, and it will come up to speed a bit faster, but the biggest advantage is less line loss and voltage drop.

[Andre Spenard]

Hi Bill - that speaks to the questions about which lugs to attach hot and neutral to.

I have answers to my questions after some research. Below, I summarize the most helpful of content I found here:https://woodgears.ca/motors/voltage.html,
and here :http://www.industrial-electronics.com/elecy4_22.html

The Jet DC motor is a capacitor start dual voltage induction motor. It uses two main windings to run. In the 120V configuration, each is supplied in parallel. In the 240V configuration, they are supplied in series.

A 3rd winding is used at the start. It is on a 120V only circuit that includes the starter winding, a capacitor and a centrifugal switch. The starter winding first gets a bump from the capacitor, then as the motor approaches operating RPMs, the centrifugal switch opens, cutting current to the winding.

As for the run windings, I’ll refer to them as A & B. In the 120V configuration, Lead #1 energizes run winding A, lead #2 energizes B. Leads #3 & #4 are the neutrals for windings A & B respectively. On my DC1182 motor, the starter circuit connections are also made in the switch box, in parallel with the run windings.
The center terminal on the block is unused in the 120V configuration.

Converting to 240V, means putting the run windings in series. This is accomplished by moving leads #2 & #3 to the center terminal. The schematics at woodgears.ca are very helpful to visualize what you are doing and why.

Due to a neat trick employed in the architecture of the run windings, the 240V configuration provides 120V to the starter circuit. This is described by Mathias Wandel in the article at woodgears.ca. His schematics were also very helpful to my visualization of what was up with the 6 leads.

The capacitor is still a point of concern. I see in the DC1100 diagram that a 40uF cap is shown for the 240V configuration. My cap does not have specs, but is labeled 120V. Since the starter circuit is always at 120V I am confused as to why a 240V 40uF cap is called for. In this thread a poster points out that the specs on the capacitor should be considered vis-à-vis the voltage conversion. I will address this with a question in reply to that poster.

I cleared up for myself why a 12-3 circuit was unnecessary. I am accustomed to running 240 for appliances. Appliances use one of the 120V legs to power circuit boards and switches, etc. If I am correct, the NEC demanded the 3rd wire to provide a dedicated neutral for the 120V circuit so that the equipment ground (bare copper wire) was not doing double duty.

Also, it is clear to me now that the 3rd pair of wires feed the starter circuit. Apparently in the newer DC models, these were pigtailed somewhere after the switch box.

I hope his is was worth the read. Many shop tools use this type of motor, so it is applicable beyond the Jet DC. For me, having some understanding of the why is very important. I don’t like just following recipes.

[Andre Spenard]

In addition to what Billy Merril posted...

Why indeed? I am the only one that works in my shop. Until I grow another set of arms, I can only use one tool at a time. Therefore, I have one 20A circuit that serves all my work stations.

Enter the Jet 2HP dust collector. It draws about 11 amps at 120V. That's nearly 75% of capacity on my single 120V circuit. Running the DC and my table saw or planer maxes out the circuit.

Since I need to run a 2nd 20A circuit, what if I make a marginal additional investment in 240V? You smirking 120V evangelicals think the advantage is so marginal that it is silly, wasteful, belt and suspenders stuff. Here's why I think it is worth it.


Motors like to draw all the current they can, as easily as possible. Their current demand ebbs and flows with the demand of the work you ask a tool to do. Motors that have to work harder to draw the current they demand run hotter and fail sooner.

So let’s compare the marginal cost of an additional leg of 60LF of THHN #12 wire to the daily relative inefficiency and overall shortened lifespan my Jet DC 1182 motor. Right. I’ll go with 240V.

In addition, if I want to convert my table saw to 240V, or add another tool that runs on 240V, I have the capacity to do so.

[Andre Spenard]

It is a question. My capacitor is marked 120V. It has no other specs marked. As I understand it, the starting circuit on this motor runs at 120V in either voltage configuration. Given that I wouldn't think on this at all, but for the DC1100 wiring diagram that shows a 40uF 250V capacitor.
So before I order a 250V capacitor, what if I wire for 240V and start it up? Can I do damage to anything other than the capacitor? Anything else i should be aware of?

Thanks.

[Bill Dufour]

Capacitor voltage is true peak to peak voltage which is about 150% of rms voltage which is what is usually stated and measured by home owner meters. 120 volts rms = 170 volts peak to peak so you need at least a 170volt rated capacitor for service on 120 volt line power. or 240 rms =340 peak to peak. This is why many caps are rated at 180 or 350 volt service.
Bill D

[David L Morse]

Capacitor voltage is true peak to peak voltage which is about 150% of rms voltage which is what is usually stated and measured by home owner meters. 120 volts rms = 170 volts peak to peak so you need at least a 170volt rated capacitor for service on 120 volt line power. or 240 rms =340 peak to peak. This is why many caps are rated at 180 or 350 volt service.
Bill D

Most motor start capacitors are rated for AC voltage. You don't need to worry about the peak value. The only time you really do that is if you are connecting two normal electrolytic capacitors back to back to make a non-polar electrolytic. Then you have to meet the peak value. AC rated capacitors are normally rated for the actual RMS AC voltage, i.e., for 120V operation you use a capacitor rated for at least 120VAC.

Or. if you are using a film or oil type run capacitor with a DC rating then, in that case, the peak value applies.