Adcock Shipley Bridgeport motor

[Clive FosterParticipant @clivefoster55965]

Colin

Pleased to hear that IDS were their usual helpful selves and that you were able to order some suitable VFD boxes.

In objective business terms I'm sure it can't really be worth their while to spend so much time with small customers but it must be really good for their reputation. Gives you that nice, warm fuzzy feeling of dealing with a trustworthy supplier and makes you confident that if, perchance, something doesn't go to plan they will help you sort things out.

Which reminds me I need to order a couple more VFD boxes later this year.

Clive

[Howard LewisParticipant @howardlewis46836]

Halving the voltage (Disregarding Impedance effects ) will halve the current (V = I * R ) so I would expect half the power, and as the speed is frequency related, half the torque.

Howard

[Robert Atkinson 2Participant @robertatkinson2]

I think Clive nailed it with a comment at the end of one of his earlier posts.

The other 3 wires are on the underside of the paxolin terminal plate. The tell-tail is the "unused" 4th terminal post. If in STAR thi will be the star point. You should be able to tell without taking the plate out by doing a resistance check. With the mains disconnected, check the resistance between the spare terminal and each of the three used ones. If the is a connection (probably only a few ohms) between the spare terminal and the other three the motor is wired as STAR. If there is no connection (>100 ohms) then it's wired DELTA.

Robert G8RPI.

Edited By Robert Atkinson 2 on 19/01/2022 20:29:40

[Robert Atkinson 2Participant @robertatkinson2]

Posted by Howard Lewis on 19/01/2022 18:07:22:

Halving the voltage (Disregarding Impedance effects ) will halve the current (V = I * R ) so I would expect half the power, and as the speed is frequency related, half the torque.

Howard

?????

Voltage is reduced / increased by the square root of 3 (1.73) for a STAR /DELTA transformation. So 240V x 1.73 = 415V for Delta and Star. Note it's the quare root of the number of phases for other multiphase systems.

You cannot ignore "impedance effects". It is the impedance and back EMF that sets the current . The resistance of the windings is a small part of the impedance and is only rsponsible of losses.
The Frequency (speed) also affects the current.

All else being equal the current and Torque reduces by about 40% when a Delta connected 415V rated motor is is connected to a 240V supply.

Note that the standard method for specifiying 3 Phase voltage is Phase to Phase. In the UK "low" voltage AC 3 Phase supply is 415V. There is no 240V 3 Phase supply as standard but one can be obtained with a one to one ratio 3 phase transformer with the Primary wired Star and Secondary wired Delta.. The 240V single Phase supply is Phase to Neutral of the 415V.

Robert G8RPI.

[Anonymous]

Posted by Clive Foster on 17/01/2022 18:38:17:

…how much power is "enough" for a Home Workshop type Bridgeport user?

Personally I'd like a bit more than 1.5hp, I've stalled my Bridgeport more than once by being over-optimistic on cut depth/width and speeds and feeds. But I'm impatient when making parts, and if a lot metal needs removing I want to do it as quickly as possible to the limit of the machine.

Andrew

[colin hamiltonParticipant @colinhamilton16803]

Robert thanks for the tip on resistance checking. This will be my first job at the weekend. Can you all please make yourselves available on Saturday morning for a raft of blurry photos and poorly constructed questions😀😀

[Robert Atkinson 2Participant @robertatkinson2]

Yes I'll be around.

[Anonymous]

Posted by Robert Atkinson 2 on 19/01/2022 21:05:39:

All else being equal the current and Torque reduces by about 40% when a Delta connected 415V rated motor is is connected to a 240V….

Thanks for confirming what I thought was the case.

Andrew

[colin hamiltonParticipant @colinhamilton16803]

I was really hoping to have a go at my motor this weekend but it turned out I needed to move everything round to fit the mill in properly. Which meant I needed to reeork the electrics completely. My nice new ring main is in and I'm thinking my shop definately benefited from a proper tidy.

I'll be back on motor electrics this week

[colin hamiltonParticipant @colinhamilton16803]

So I definately dont have the option of reconfiguring the motor. There are only 3 wires. I'm going to try running it as is, perhaps trying to fool it as per the referenced blog post. If that's no good I think I will swap the motor out and perhaps take the opportunity to up the power to 2hp.

[noel shelleyParticipant @noelshelley55608]

Isn't star point opposite the wires bound up ? It will be there somewhere ! Noel.

[Clive SteerParticipant @clivesteer55943]

Hi Colin

I think I can see 6 tails from the windings sleeved in yellow. Three, will be combined to form the star point but will have no other connection. The other ends will be connected to each of the red wires.

The down side is that to convert you have to cut the tie threads find the start point and connect a wire to each of the wires and then retie. You can use soft solder for the joins but it is better to use crimps as these won't let go if the motor or wire get overheated on overload. Just copy how the current joints are made and extra insulation sleeving is applied.

Clive S

[EmgeeParticipant @emgee]

Colin

If you are fitting a new shielded cable supply to the motor it will be a good idea to get the correct gland type, the one fitted is OK with the original (Adaptaflex ?) cable but not suited to flexible cable.

Emgee

[colin hamiltonParticipant @colinhamilton16803]

Blimey,

So I need to go deeper. Can I just confirm what I'm going to have a go at.

Release the wires bound onto the top of the stator.

Find three wires connected together (potentially the yellow ones).

Separate the three wires and assume them to be the finish end of the three windings.

Select each of the three (yellow) wires in turn and using continuity find its matching red wire. Mark up the wires so I know what's what.

Bring all 6 wires back up top and reconnect them for delta

Is that it?

[Chris Evans 6Participant @chrisevans6]

I would find working on that motor scary and take it to a rewind place. My 3HP lathe needs a similar procedure but I could not find anyone willing to do it. It runs OK on a Transwave static inverter whereas the 2HP Bridgeport would only run for a few minutes on the Transwave before tripping out. Bridgeport now happy on a VFD fitted by a friend.

[EmgeeParticipant @emgee]

Posted by Chris Evans 6 on 27/01/2022 11:26:16:

I would find working on that motor scary and take it to a rewind place. My 3HP lathe needs a similar procedure but I could not find anyone willing to do it. It runs OK on a Transwave static inverter whereas the 2HP Bridgeport would only run for a few minutes on the Transwave before tripping out. Bridgeport now happy on a VFD fitted by a friend.

Hi Chris

Have you fitted a 400v 3 phase output VFD or are you running the motor at reduced voltage/power than the rating plate ?

Emgee

[colin hamiltonParticipant @colinhamilton16803]

Posted by Chris Evans 6 on 27/01/2022 11:26:16:

I would find working on that motor scary and take it to a rewind place. My 3HP lathe needs a similar procedure but I could not find anyone willing to do it. It runs OK on a Transwave static inverter whereas the 2HP Bridgeport would only run for a few minutes on the Transwave before tripping out. Bridgeport now happy on a VFD fitted by a friend.

Scary yep I would agree. But I'm also thinking it's still only wires. Worst comes to the worst I'm in for a new motor which is likely anyway if I can't sort it so what do I have to loose?

[Chris Evans 6Participant @chrisevans6]

Posted by Emgee on 27/01/2022 12:01:43:

Posted by Chris Evans 6 on 27/01/2022 11:26:16:

I would find working on that motor scary and take it to a rewind place. My 3HP lathe needs a similar procedure but I could not find anyone willing to do it. It runs OK on a Transwave static inverter whereas the 2HP Bridgeport would only run for a few minutes on the Transwave before tripping out. Bridgeport now happy on a VFD fitted by a friend.

Hi Chris

Have you fitted a 400v 3 phase output VFD or are you running the motor at reduced voltage/power than the rating plate ?

Emgee

As far as I am aware the Bridgeport now runs 240 volt three phase from the VFD. Not found any lack of torque or power. I am just not confidant to mess with electrical items.

Chris

[Andrew TinsleyParticipant @andrewtinsley63637]

A pity you don't feel confident to rewire in delta. That motor looks to be an easy conversion. However full marks for expressing your concerns about your ability.

Where are you located, someone may be near enough to do the job for you?

Andrew.

[Clive SteerParticipant @clivesteer55943]

Colin

Your list of steps to take is correct. Probably the most difficult task will be doing the retying to hold the wires in place as threading through a cord can be tricky. However if you just snip the original loops but initially leave them in place and you may be able to use them to pull new thread through. However you can use small thin cable ties instead.

From what I can see from your pictures you will probably find three wires, sleeved in yellow, emerging from the coils on the outer rim of the windings. Another three wires will emerge from their respective windings nearer the centre.

It doesn't really matter what are start and finishes of the windings provided you can identify each of the three individual windings so you can connect them in true delta configuration. The marking is only required to ensure the motor will rotate in the right direction when connected to a 3 phase supply but if it doesn't swapping any two phase wires will make it rotate in the opposite direction.

If you'd like to PM me I'll give you my phone number and I can talk you through the process as you do it. If you can make a FaceTime or Zoom call I can watch you do it and comment.

Clive S

[colin hamiltonParticipant @colinhamilton16803]

Clive thank you for the very kind offer I'll pm you now

[Clive FosterParticipant @clivefoster55965]

On all the motors I've done shellac, varnish or similar protective coatings had been applied after tying. So things still stayed in place after snipping the string.

Adhesion wasn't high. More than post it note, less than sellotape. So some careful pulling and prising with non-metallic tools got the bits I needed to work on up and out into free space with minimal disturbance to the rest.

I left most of the old string behind as it clearly wasn't going to come out easily. Just snipped the trailing ends neatly close to the wiring. The coating soaked string was approaching MIG wire stiffness. Re-tied with some nice cotton string 'cos I had some.

Dunno what the modern advice is on re-coating. I "obtained" a small bottle of the then proper stuff about 40 years ago. Behaves like shellac in that it separates out of the carrier liaquid quite quickly and needs regular stirring up.

Clive

[colin hamiltonParticipant @colinhamilton16803]

Clive

What is the purpose of the shellac? Is it simply to stiffen up the ties to ensure they don't come undone? I was planning to replace with zip ties.

[Mike PooleParticipant @mikepoole82104]

I think the purpose of the shellac was to stabilise the windings so that the wires could not fret and compromise the insulation, these days it seems to be a liquid epoxy. We used to use a flat cotton tape like the motor in the pictures and the shellac would be absorbed to deny any possibility of moisture being absorbed. We would use an off cut of the winding wire as a needle to thread the tape through the windings, bent to form a blunt end to avoid damaging the windings. The interconnections were made by twisting the ends and flashing them with an oxy-acetylene torch to fuse the connection into a neat ball. To solder the ends to the tails it is easy to burn the insulating varnish off the wire and scrape clean, just scraping is not so easy as the coating used Is extremely tough, if you use a flame use a small one and keep an eye on where you point it.

Mike

[Clive FosterParticipant @clivefoster55965]

Colin

I don't know if the stuff I have or that on the motors I did actually is shellac but it clearly builds thin layer of insulation over everything.

I imagine the idea is to stop the string moving around due to vibration so it doesn't eventually work its way through the insulation coating on the wire causing turn to turn shorts. Clearly a bad thing. As I understand it the wire in the coils have vibrational forces on them when the motor is running, think transformer hum, so some sort of restraint is needed.

Clive

Edited By Clive Foster on 28/01/2022 09:43:38

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