Series II Bridgeport electrical diagrams
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  1. #1
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    Default Series II Bridgeport electrical diagrams

    I recently purchased a series 2 bridgeport at an auction. It had a label on the panel that it was 480v, and I confirmed the wiring in the spindle motor was wired up for high voltage. I do not have 480v in my shop (rotary phase converter), and would like to get this wired back to 240v. I can do the motor easy enough, but am lost when it comes to what needs to be changed in the panel. Worst case, I can should be able to pick up a transformer fairly cheap at an upcoming auction, but if I can get it back to 240v, that would be preferred.

    Of course, then I'll have to move out my old mill and hope to not have to totally rearrange everything, as this thing makes my old 10x50 Bridgeport clone look tiny.

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    I'm not sure what electrical components are in the control panel for your mill, but typically there will be incoming line fuses, a control transformer and a reversing contactor or magnetic starter. When changing the supply voltage from 480V to 240V, the current ratings will double. You will need to change the incoming line fuses to the proper current rating (likely double what the existing 480V fuses are rated for). The control transformer should have line side taps for 240V and you will have to connect to those taps from their current connections on the 480V taps. If there are magnetic starters, they will have heaters that will need to be changed to the proper current rating for motor protection. You can find this information on the component manufacturers website.

    Ted

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    Thanks, right now, I'm looking to see if I can find a transformer fairly cheap, and use that to test the machine out. If I can't find one, I'll start looking at what you mentioned. The wiring inside the cabinet isn't terrible, but also not the cleanest in the world, so tracing things (with my limited skill set), would be more of a challenge.

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    I'm not sure what your intent is for purchasing a transformer. Do you plan to use a buck/boost transformer to step up your incoming 240V power supply to 480V to be able to operate the machine as it is currently wired ?

    Ted

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    Quote Originally Posted by talvare View Post
    I'm not sure what your intent is for purchasing a transformer. Do you plan to use a buck/boost transformer to step up your incoming 240V power supply to 480V to be able to operate the machine as it is currently wired ?

    Ted
    Planning on getting something like this. Will take 240 from my 3 phase panel through this, and feed the machine.
    3 kVA-75 kVA 3 Phase Transformers: 480-240-Volt | NAPCco

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    If I understand your situation correctly, you have single phase 240V power to your shop and you are using a phase converter to obtain 240V three phase power. You mention that you have a three phase panel. I'm guessing that this panel is fed from the phase converter. If this is the case, you don't need another transformer. You said the mill has a dual voltage motor, so as you've said, you can just change to the low voltage wiring configuration at the motor. I don't know what electrical components are in the control panel on your mill, but if it is original equipment and the machine was designed to operate on either 240V or 480V three phase power, then you should be able to convert the components in the control panel to accept 240V input as I outlined in my first post. If I am mistaken in my assumption about your existing electrical service in your shop, let me know and I will try to help.

    Ted

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    Quote Originally Posted by talvare View Post
    If I understand your situation correctly, you have single phase 240V power to your shop and you are using a phase converter to obtain 240V three phase power. You mention that you have a three phase panel. I'm guessing that this panel is fed from the phase converter. If this is the case, you don't need another transformer. You said the mill has a dual voltage motor, so as you've said, you can just change to the low voltage wiring configuration at the motor. I don't know what electrical components are in the control panel on your mill, but if it is original equipment and the machine was designed to operate on either 240V or 480V three phase power, then you should be able to convert the components in the control panel to accept 240V input as I outlined in my first post. If I am mistaken in my assumption about your existing electrical service in your shop, let me know and I will try to help.

    Ted
    Yep, you are exactly correct. My biggest concern with rewiring my mill controls is I really don't have a lot of experience with control circuits and that type of thing, and the wiring isn't all that clean in the cabinet. My fear is that I would mess up some of the wiring, and make it non-operational. I found a transformer semi-locally for $160, so just trying to weigh out the better option at this point.

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    Assuming the mill was operational on 480V when you got it, you can do as you're suggesting and boost your current 240V three phase power from your panel to 480V three phase with a transformer and just connect that to the input on the mill control panel and you should be good to go. Don't have to re-wire anything. I'm attaching a photo I found on the internet of a Bridgeport control panel. If the components in your mills control panel look like what's in this photo, you should be able to convert to 240V three phase input without using an additional transformer, although you will have to change fuses, heaters and re-configure the wiring on the transformer.
    (can't seem to rotate the photo)

    Tedbridgeport-electrical-panel.jpg

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    Yeah, that's pretty close. Here is my panel. Not sure why its so small, but second one is a bit bigger.
    Attached Thumbnails Attached Thumbnails bridgeport.jpg   bridgeport.jpg  

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    It looks like you have a control transformer in the electrical cabinet,top centre.
    Have a look on either side as it may be a multi tapped version which means you may be able to connect it for 240v just by moving a wire.
    If you see a row of unused terminals with different voltages next to them then you are in luck,it should be in the 480v one now, if it has a 240v one then the lead needs removing from the 480v and putting in the 240v.
    My 1969 vintage has this but as I'm in the uk it may be different.
    As far as I've seen all the control circuits run at 110v ac so the transformer just steps it down to that for the control side.
    If you can get a photo of the transformer connections that would help.

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    Quote Originally Posted by Oilyneil View Post
    It looks like you have a control transformer in the electrical cabinet,top centre.
    Have a look on either side as it may be a multi tapped version which means you may be able to connect it for 240v just by moving a wire.
    If you see a row of unused terminals with different voltages next to them then you are in luck,it should be in the 480v one now, if it has a 240v one then the lead needs removing from the 480v and putting in the 240v.
    My 1969 vintage has this but as I'm in the uk it may be different.
    As far as I've seen all the control circuits run at 110v ac so the transformer just steps it down to that for the control side.
    If you can get a photo of the transformer connections that would help.
    If you mean the brown rectangular thing, here are the right and left side. First pic is the left side, second pic is the right side.
    Attached Thumbnails Attached Thumbnails leftside.jpg   rightside.jpg  

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    As Oilyneil said, the electrical component in the top center is your control transformer. The "H" terminals are the high voltage input terminals. The "X" terminals are the low voltage output terminals. The transformer is currently configured for the high voltage (480V) configuration. You need to remove the center tie bar between H2 & H3 and tie H1 & H3 together and H2 & H4 together. This will give you the low voltage input connection (240V). You will still need to change the fuses (top right corner of the panel) and the heaters in the magnetic starter (looks like the component in the top left corner of the panel). You may be able to get by without changing fuses and heaters if the mill is run with very light loading, but it is very likely that you will blow the existing fuses as they should be sized for the 480V supply voltage. The existing heaters will also be sized for 480V supply voltage and will very likely trip the overcurrent protection in the magnetic starter. Also, it appears that your control panel has had some modification by a previous owner and I can't tell if one of the other components in the middle of the panel is the reversing contactor/magnetic starter and whether or not it also has heaters in it.

    Ted

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    Quote Originally Posted by talvare View Post
    As Oilyneil said, the electrical component in the top center is your control transformer. The "H" terminals are the high voltage input terminals. The "X" terminals are the low voltage output terminals. The transformer is currently configured for the high voltage (480V) configuration. You need to remove the center tie bar between H2 & H3 and tie H1 & H3 together and H2 & H4 together. This will give you the low voltage input connection (240V). You will still need to change the fuses (top right corner of the panel) and the heaters in the magnetic starter (looks like the component in the top left corner of the panel). You may be able to get by without changing fuses and heaters if the mill is run with very light loading, but it is very likely that you will blow the existing fuses as they should be sized for the 480V supply voltage. The existing heaters will also be sized for 480V supply voltage and will very likely trip the overcurrent protection in the magnetic starter. Also, it appears that your control panel has had some modification by a previous owner and I can't tell if one of the other components in the middle of the panel is the reversing contactor/magnetic starter and whether or not it also has heaters in it.

    Ted
    Thank you so much! This is extremely helpful, and I can definitely handle it. The gray contactor/starter in the middle is definitely not original to the machine, but everything else appears to be right.
    Attached Thumbnails Attached Thumbnails 20191020_185005.jpg  

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    Quote Originally Posted by cj7jeep81 View Post
    The gray contactor/starter in the middle is definitely not original to the machine,
    That Furnas mag starter also has heaters. The heaters are the little things at the bottom that look like coil springs. The mag starter (if that's what it is) in the upper left corner appears to be from a different manufacturer and uses a different style of heater. Even if the mag starter has a Bridgeport name tag on it, it is almost surely manufactured by one of the major electrical component manufacturers like Allen Bradley, GE, Square D, etc. You can go to the manufacturers web site and find a chart to obtain the correct heater for your application.

    Ted

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    Quote Originally Posted by talvare View Post
    That Furnas mag starter also has heaters. The heaters are the little things at the bottom that look like coil springs. The mag starter (if that's what it is) in the upper left corner appears to be from a different manufacturer and uses a different style of heater. Even if the mag starter has a Bridgeport name tag on it, it is almost surely manufactured by one of the major electrical component manufacturers like Allen Bradley, GE, Square D, etc. You can go to the manufacturers web site and find a chart to obtain the correct heater for your application.

    Ted
    Thanks,for now, I'll just move those jumpers around to set it to low voltage. That way I can at least function test the machine, and see how it works. If there aren't 2 jumpers on the transformer, does it matter what I use to make one?

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    You can make the jumpers from copper wire. I would recommend using a minimum 12ga.

    Ted

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    Quote Originally Posted by talvare View Post
    You can make the jumpers from copper wire. I would recommend using a minimum 12ga.

    Ted
    Got it fired up! There were two tie bars there, just had to loosen the screws, and swing them into place. Spindle is quiet, and power feed works in all 3 directions. Thanks for all the help, I really appreciate it!

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    You're welcome. Glad you got it running.

    Ted

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