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Adcock Shipley Bridgeport motor

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Andrew Johnston18/01/2022 09:30:07
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6574 forum posts
701 photos

Clive: Thanks for the link. I took the original post to imply that if you had a motor designed to run at 415V, 50Hz and star connected, but ran it at 240V and 50Hz, the torque would drop to a quarter of the original value. I don't understand why that should be?

Andrew

DiogenesII18/01/2022 10:00:10
516 forum posts
202 photos

G&M Tools   Apologies, Project Machinery have a used Transwave 1.2 Kw phase convertor listed, 415 output, £ couple of hundred.. ..an use?

Edited By DiogenesII on 18/01/2022 10:01:26

colin hamilton19/01/2022 08:25:21
137 forum posts
57 photos
Posted by Clive Foster on 17/01/2022 17:34:29:

Andrew

Inverter Drive Supermarket have a nice blog post covering running a 400 V (nominal) star connected motor from a 230 V (nominal) inverter.

**LINK**

https://inverterdrive.com/HowTo/240V-Supply-to-a-400V-AC-Motor/

Clive

Thanks for the very useful link. It is a very informative read. There are a number of very useful articles on their page. I phoned them yesterday to discuss VFDs in general and the lady who wrote that article spent at least half an hour taking me through it all. It was such a pleasure to speak to someone so informed and helpful I will always be going going to them for all my VFDs *I ordered 2 yesterday!!)

Clive Foster19/01/2022 09:31:26
3103 forum posts
107 photos

Andrew

I suspect the confusion about torque and power loss was due to thinking in DC motor terms where half the voltage means half the current which means half the torque then if running at half speed you have 1/4 power. Or something of that lik.

Clive

Clive Foster19/01/2022 09:38:18
3103 forum posts
107 photos

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 Lewis19/01/2022 18:07:22
6005 forum posts
14 photos

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 219/01/2022 20:28:52
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1195 forum posts
20 photos

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 219/01/2022 21:05:39
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1195 forum posts
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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.

Andrew Johnston19/01/2022 23:59:06
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6574 forum posts
701 photos
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 hamilton20/01/2022 07:43:53
137 forum posts
57 photos

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 220/01/2022 11:42:51
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1195 forum posts
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Yes I'll be around.

Andrew Johnston20/01/2022 16:08:18
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6574 forum posts
701 photos
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 hamilton24/01/2022 10:59:33
137 forum posts
57 photos

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

20220122_130510.jpg

colin hamilton26/01/2022 20:04:37
137 forum posts
57 photos

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.

20220126_173425.jpg

20220126_173415.jpg

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noel shelley26/01/2022 21:18:05
1278 forum posts
21 photos

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

Clive Steer26/01/2022 21:56:57
91 forum posts
5 photos

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

Emgee26/01/2022 22:27:10
2404 forum posts
285 photos

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 hamilton27/01/2022 10:21:57
137 forum posts
57 photos

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 627/01/2022 11:26:16
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2050 forum posts

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.

Emgee27/01/2022 12:01:43
2404 forum posts
285 photos
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

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