Transformer wiring...what do I need?

I am trying to operate a Wadkin planer/jointer machine that has 2 3ph, 575v motors. I have 3ph 208 and plan to install a 208-600v transformer. Can someone help me out with the details of what this circuit would look like? Would motors be directly wired to secondary side the transformer? Or could I have a receptacle between transformer and machine to just plug it in? On the primary side of the transformer, could I have cord/plug to plug into an existing 208 3ph receptacle or would I go directly to the panel? Would the cord on the primary side need to be rated for the higher voltage? Where along this circuit will I actually be turning the machine on and off? I plan on having a professional do the install but I need to have a modest understanding to supply materials.

Look at your PJ. Its common for industrial machines to have magnetic starter(s) ("switches") and even disconnects on board

In my Freeman catalog, both the Wadkin JOINTER and PLANER have electricals in an enclosed and covered part of the base casting

Where along this circuit will I actually be turning the machine on and off?

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Hannah, are you a big shop that has to meet OSHA and other requirements, or are you a one person outfit who will never see any inspectors? Might make a difference in terms of what you realistically need to do.

I am in the latter boat, have a 460v shaper running from a 240/480 transformer. I go from a heavy 3ph extension cord to a plug connected to a 240v fused disconnect hardwired to input of transformer, 460 output of transformer hardwired to built in switch of the machine. Disconnect energizes transformer, built in switch turns on & off. I think you will find most wire is rated to 600v.

Lots of guys smarter and more experience than me will give you much better advice, but that is what works for me.

Is it a RM? I think it was originally a 550v motor. Very cool machine. All machines need some kind of disconnect. A plug counts. I prefer a fused disconnect on both sides of a transformer ,then a plug.

As for trany size, a 9-15 kVA will do. But the trany size dictates the size of wire. The voltage in wire dictates the voltage rating of sheath.

The machine is a 12" Wadkin BAO/S, I believe from 60's or 70's. Based on research (and crawling underneath the machine with a mirror taped on a stick...the motor tags were darned near impossible to read), I believe the motors are original. Came from Canada, hence the reason for the high voltage motors. I am in Philly, though, and there is no such industrial power supply in my building.

So I am going to work backwards here. I have a 3ph 208 outlet on a 15 amp circuit breaker. From the receptacle, an extension cord to a 208 fusible disconnect. From the disconnect to the transformer. From the transformer to...and this is where my question is...to the starter on the machine? Does the starter serve the same purpose as a fused disconnect? Are they one in the same?

richard newman said:

Hannah, are you a big shop that has to meet OSHA and other requirements, or are you a one person outfit who will never see any inspectors? Might make a difference in terms of what you realistically need to do.

I am in the latter boat, have a 460v shaper running from a 240/480 transformer. I go from a heavy 3ph extension cord to a plug connected to a 240v fused disconnect hardwired to input of transformer, 460 output of transformer hardwired to built in switch of the machine. Disconnect energizes transformer, built in switch turns on & off. I think you will find most wire is rated to 600v.

Lots of guys smarter and more experience than me will give you much better advice, but that is what works for me.

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This sounds ideal for me. I am a one (wo)man band. If L&I comes by, I'll just throw a blanket over the transformer real quick.

Does the starter serve the same purpose as a fused disconnect? Are they one in the same?

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No, the fused disconnect, sometimes called a safety switch, disconnects power to machine

Starters are motor contactors for turning on/off individual motors. They can be manually or magnetically operated. The mag jobs often have remote push button stations - even if remote is just around the corner of the machine. Mag jobs very often have thermal overloads that disable the mag circuit (shut down motor) for protection

It is not uncommon to have BOTH disconnect and starter(s) in SAME electrical enclosure

Wadkin may have had their own ideas on the subject - and not necessarily in accordance with North American practice

johnoder said:

Wadkin may have had their own ideas on the subject - and not necessarily in accordance with North American practice

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That's odd - my geography teacher told us that Canada was part of North America.

George

duplicate post

hannahbsturm said:

... and crawling underneath the machine with a mirror taped on a stick...

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I've had a lot of success with a small digital camera instead of a mirror. You can get into quite difficult places with it, take a flash photo (or two, or three...) at arm's length if need be. Then you can read the labels sitting down in comfort with a cup o' tea and a biscuit.

George

Goerge

My most humble and abject apologies - I assumed Wadkin was UK

Georgineer said:

That's odd - my geography teacher told us that Canada was part of North America.

George

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Wadkin was produced in England. They built to CSA standards. I Believe the US excepts electrical safety standards that meet or exceed US UL rating. 550V was a old industrial voltage. Now it's 600V.

Matt Matt said:

I prefer a fused disconnect on both sides of a transformer

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Why two disconnects? One disconnect for the transformer, the other for the motor? My machine does not appear to have its own disconnect: it's a magnetic starter w/ (I assume) overload protection. If a starter protects a motor from overload, what's the purpose of having a fused disconnect in addition to the starter? The starter is not original to the machine..it appears to have been replaced in the past decade or so.

Some basic concepts of power wiring... A disconnect is used to allow a machine to be totally disconnected from power, and locked out, so it can be serviced safely. For low horsepower applications, the plug on the line cord qualifies as a disconnect. In the case of a machine with a magnetic motor starter, there is still power in the cabinet to power the start switch even when the motor isn't running. Locking out the disconnect assures there is no power in the machine control cabinet when you open it.

Fuses are used any time the wire size decreases below what the whole circuit is fused for. For instance, a 60A branch circuit runs from the breaker panel to supply several machines, each of which only draws a maximum of 20A. Each machine would have a fused disconnect with 20A fuses, and could use much smaller wire beyond the disconnect.

Since it is not safe to pull fuses on a live circuit, fuses are usually combined with a disconnect so that the means of removing power from the fuses is right at hand.

In the case mentioned above, with a fused disconnect on either side of a transformer, the one on the LINE (supply) side disconnects the transformer, with fuses sized for the local circuit. If the transformer is the only thing on that circuit, it may not be needed, the breaker in the panel serving the same function. Since a step-up transformer increases the voltage, the current on the high voltage side will be less, so the fuses on the LOAD (downstream) side are sized to protect the smaller wire used from that point on.

Hope this helps,

Dennis

It will probably be smarter and cheaper to associate the transformer with the equipment directly. Disconnects and plugs, etc tend to be considerably more expensive for the 600 volt class than for 230V. If you can do that, then the problem becomes simpler, you just have normal 230V to deal with.

The transformer may be protected by fuses etc on the primary side only, if the secondary side conductors (wires) are rated for the secondary side current. In this case, I presume that the motor in the saw is itself protected sufficiently to connect it to a regular branch circuit at its rated voltage. If so, no need for anything special between the transformer and the saw. All the breakers and disconnects can be on the low voltage (230V) side.

Matt Matt said:

...They built to CSA standards. I Believe the US excepts electrical safety standards that meet or exceed US UL rating. ...

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The US (for instance OSHA) officially accepts NOTHING other than US NRTL recognition or listing. CSA and UL have an agreement, with a "CUL" dual listing setup, but that is newish and would not apply to older stuff. Many pieces of equipment have multiple acceptances, including UL or ETL as well as CE, CSA and so forth. That said, local inspectors may accept CSA or not for purposes of the electrical code. It's the local jurisdiction and their rules.

I have seen perfectly good european equipment made with only CE mark disapproved by the local inspector. The company which had the stuff was forced to pull it out and replace it with items having UL / ETL / etc. It was silly, but he was within his rights and duty bound to insist on it per the rules he worked within.

Modelman said:

If the transformer is the only thing on that circuit, it may not be needed, the breaker in the panel serving the same function.

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The transformer would be connected to a 208 3ph receptacle, which is the only thing on the circuit. I have a small shop with my own service panel. Since I could cut power to the circuit directly at the panel, could this, as you say, serve as a disconnect?

On another note, I want to make sure I am using the proper wire. The machine will be drawing about 5 amps at 600v. Circuit has a 15-amp breaker. From the outlet to the transformer, would I use just 12 or 14 gauge wire? What about between the transformer and the starter?

I realize I must sound clueless, so thanks for bearing with me...this is not my terrain. Just want to get this thing going...

hannahbsturm said:

The transformer would be connected to a 208 3ph receptacle, which is the only thing on the circuit. I have a small shop with my own service panel. Since I could cut power to the circuit directly at the panel, could this, as you say, serve as a disconnect?

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Disclaimer: I am not a licensed electrician.

I agree with JST, mount the transformer on, or near the machine, and do all the supply wiring as low voltage, wiring directly from the transformer to where the power used to enter the machine's control cabinet. I believe the breaker in the panel could qualify as a disconnect, IF it is visible from the machine. Personally, I would lose the plug, buy a 30A disconnect off e-bay, and wire the transformer directly to the disconnect, which ensures you have a disconnect right by the machine where you'll use it when working on the machine. If all the wire to the machine is larger than what the breaker is sized for, no need for a fused disconnect. See below.

On another note, I want to make sure I am using the proper wire. The machine will be drawing about 5 amps at 600v. Circuit has a 15-amp breaker. From the outlet to the transformer, would I use just 12 or 14 gauge wire? What about between the transformer and the starter?

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Current and voltage are inversely proportional, so 5A at 600V is going to be about 14.5A at 208V, and I see a problem, in that breakers are typically rated to continuously carry only 80% of their nameplate rating, so a 15A breaker is really too small; the branch circuit should be 20A. A 20 circuit calls for 12 gauge wire. 12 gauge is easy enough to deal with that I don't see any advantage to try to use smaller wire downstream of the transformer, and would just use that all the way to the starter. Keep in mind that solid conductor wire is OK for the circuit where it is mounted to the wall, but there will need to be some sort of flexible "whip" to the machine, and stranded wire should be used for the whip and anywhere on the machine, as it is less likely to work harden and break from vibration.

The whip either needs to be rubber insulated cord or in armor. Unfortunately, dealing with a three phase circuit you need four wires (three power wires and a ground wire) and the big box stores like Home Depot typically don't carry any four conductor cord, or three phase breakers or disconnects, so this will have to come from an electrical supply house. Either Grainger or McMaster-Carr (my choice) has it all, but a local supply house with a helpful counterman would make selecting wire, cord, cord grips or Seal Tight armor and fittings easier. The Devil, it seems, is always in the details.

I realize I must sound clueless, so thanks for bearing with me...this is not my terrain. Just want to get this thing going...

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Hey, we all had to start somewhere. Good luck.

Dennis

I personally like to start at machine and work backwards. The machine requirements are 5 A at 600 V. I'm assuming that the contactors, heaters, all internal wiring is proper. The cord running from the machine to transformer needs to be rated at 600 V. 600 V flexible machine wire is called SOOW not SJOOW( or tech90 or equivalent shielded 600 V rated) . This cord needs to be rated to the transformer Size. If this transformer is 208 to 600-6kVA, The amperage output can be as high as 5.77 A , The input would be around 16.6 A at 208V . Your transformer will need to be fed a 20 amp circuit with all lines provisioned for 300 V and proper installation (i.e. Shielded if required)

The reason why I would put a fused disconnect on both sides of the transformer is merely as I use it for distribution. When I have a 600 V line providing a 45 KV a transformer stepping down to five different machines, each machine has their own fused disconnect. But my main is 600 V. So I'm running everything backwards to you.

As mentioned before stepping up voltages you need a properly rated transformer. Generally autotransformers don't care which way the voltage is coming from. What size transformer are you using or have? Can you post a picture of its name plate?

I do not have the transformer yet..eyeing this one on ebay.

Eaton Y6G28T9N Transformer 3PH 6V Delta 28Y 12V 9KVA XLNT | eBay

I have recently had a similar problem with an inspector. After doing a bit of research, I found that the CE mark is not a testing approval. It is a declaration by a company that they are in compliance with CE standards. There are no tests necessary, just the declaration of conformity.
Inspectors here need something more than that and will insist upon a Nationally Recognized Testing Laboratory's stamp. NFPA 70 requires NRTL stamp on all new equipment, Though you can appeal their ruling.

Having been a UL test technician, I can attest to the fact that everything with a UL mark is tested fairly rigorously.