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  1. #121
    grain_r's Avatar
    Lives in Coalville, United Kingdom. Last Activity: 19 Hours Ago Has been a member for 9-10 years. Has a total post count of 89. Received thanks 1 times, giving thanks to others 3 times.
    Hello
    I am looking at CY Cable at the moment and I see most have been using 4 core with the earth as the outer sheathing, But I have seen a 5-core CY cable and thought that might be a better option. but just wondering if the Earthing on the outer cable is being used to help with shielding.

    https://www.edwardes.co.uk/categorie...flexible-cable

    thank you

  2. #122
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 4 Days Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,908. Received thanks 360 times, giving thanks to others 8 times.
    The main reason for CY cable, is for the screen, which should be connected to ground at one end only (if you connect both ends, you risk creating a ground loop which will cause even worse noise problems)

    For steppers, there should be no need to add an additional earth wire, and for a 3 phase spindle you only need 3 power wires, with the other connected to ground far safety.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  3. #123
    Quote Originally Posted by grain_r View Post
    Hello
    I am looking at CY Cable at the moment and I see most have been using 4 core with the earth as the outer sheathing, But I have seen a 5-core CY cable and thought that might be a better option. but just wondering if the Earthing on the outer cable is being used to help with shielding.

    https://www.edwardes.co.uk/categorie...flexible-cable

    thank you
    4 core is the normal. The screen should be grounded to the star point in the control box . the screen should not connect to the motor case. ie grounded one end only

    ( star point is where all the various earths are made to avoid ground loops)
    ..Clive
    The more you know, The better you know, How little you know

  4. #124
    grain_r's Avatar
    Lives in Coalville, United Kingdom. Last Activity: 19 Hours Ago Has been a member for 9-10 years. Has a total post count of 89. Received thanks 1 times, giving thanks to others 3 times.
    Thank you very much for that I will go with the 4 core then, And thank you both for saying about the Ground loop possibility I would have fallen down that hole. I just assumed it would be both ends.

    Because I am using a computer tower as the case I am looking at a din rail to the earth wire from the power and then using a termination block to connect to and then not earthing the case I'm guessing that will be the same thing.

  5. #125
    grain_r's Avatar
    Lives in Coalville, United Kingdom. Last Activity: 19 Hours Ago Has been a member for 9-10 years. Has a total post count of 89. Received thanks 1 times, giving thanks to others 3 times.
    I'm sorry Although I can put things together the electronics design is certainly not in my comfort zone.

    Because I'm trying to fit the power supply in a relatively small space I'm wondering if it is possible to make a PCB to mount the components to?.

    But I'm unsure If the power being taken from it will just burn the tracks but because it will only be 70v I wasn't then sure the plan would be to make a PCB after the bridge rectifier and then mount the capacitors and then PCB mounted terminal block.

    I have been looking at terminal blocks and they have rated around 10 Amp also a kettle lead c14 style plug as my main power which is rated around 10 Amps but with the 4 Nema 23 motors showing around 2.8-3 Amps and the VFD and 2.2 Kw Spindle running around 10 Amps I'm unsure if I can power the system with just one incoming connection?

    I'm wondering how people do it do they bring their powers from separate rings directly to the enclosure and then run the VFD and spindle from one RCD Ring and the rest of the system from another Ring?

    Or quite possibly am I wrong about the amount of power it will use at any one time and it will be okay to run it from a kettle lead plug and run the lot?

    I'm sorry if It's a silly question I just want to keep a decent safety zone on the cables.

    thanks

    Rob

  6. #126
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 4 Days Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,908. Received thanks 360 times, giving thanks to others 8 times.
    Just looked back, and you could probably have done with a bigger enclosure.

    You won't really save that much space using a PCB for the main PSU.
    Just bolt the toroid to a side of the case, then use a big capacitor with some screw terminals and a suitable mount for the capacitor to keep it secure and located. The bridge rectifier also just needs mounted to something flat that'll also act as a heat sink (I've mounted the toroid, cap, and rectifier on a bit aluminium plate in the past).

    Then wire the stepper drivers directly to the capacitor terminals. They shouldn't be fused, so there is no need to have that wiring pass through anything else.


    I'd be more inclined to hardwire a power lead, rather than use an IEC connector.
    Total consumption isn't likely to be that high. At 240V, the steppers are not likely to use more than an amp or two. Even if you were to manage running them all at high enough speed to get the full current through every motor, that is only 2Ax70Vx4, which is 560W or about 2.33A, but you'll never manage that. You'll be lucky if they ever peak above 1.5A.

    I'm assuming you'll be using a pretty standard 2.2KW spindle?
    At full power, that will be about 10A.

    If you really want a connector, a C13/14 will likely be OK provided you use good quality ones as it's quite unlikely you'd exceed the 10A rating for any length of time, or you could go up a size to C15/16.


    The bigger issue is likely to be inrush current when you turn things on.
    I'd add an inrush limiter to the toroid, just to ease the power on surge.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  7. #127
    grain_r's Avatar
    Lives in Coalville, United Kingdom. Last Activity: 19 Hours Ago Has been a member for 9-10 years. Has a total post count of 89. Received thanks 1 times, giving thanks to others 3 times.
    Hello m_c

    Thank you very much for the reply, that's great that it's a lower amperage than I thought it would use. You are right Ideally I would use a bigger case but I think it will all fit in even though it might be a little snug for any issues that arise after for fault finding. I will look at the inrush limiter to ease the surge that sounds like a good idea. and I will work on the max 10 amp for the highest needed.

    Thank you

  8. #128
    grain_r's Avatar
    Lives in Coalville, United Kingdom. Last Activity: 19 Hours Ago Has been a member for 9-10 years. Has a total post count of 89. Received thanks 1 times, giving thanks to others 3 times.
    After m_c had said about the inrush limiter I have been looking at various options but I have found this on amazon and just wondering if I could use that

    https://smile.amazon.co.uk/gp/produc...SBGN3D0P&psc=1


    The Description shows

    Soft start for power tools with brush motor from 220-250 volts max. 12 A (tested to 2500 watts)
    Includes extensive accessories such as cable extensions and plugs/terminals
    Suitable for angle grinders, table saws, hand circular saws, routers, chop saws and mitre saws
    Restriction of the inrush current, protects the bearings
    Compatible with machines of leading manufacturers


    Click image for larger version. 

Name:	SoftStart Motor.jpg 
Views:	42 
Size:	43.0 KB 
ID:	31680


    or if there is a better way for the inrush limiting.

    thanks

    Rob

  9. #129
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 4 Days Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,908. Received thanks 360 times, giving thanks to others 8 times.
    A basic thermistor is cheaper, such as https://uk.rs-online.com/web/p/thermistor-ics/2579500

    Although they do take about 2 minutes to cool down and prevent a surge, if you need to turn the machine off and on again.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  10. #130
    grain_r's Avatar
    Lives in Coalville, United Kingdom. Last Activity: 19 Hours Ago Has been a member for 9-10 years. Has a total post count of 89. Received thanks 1 times, giving thanks to others 3 times.
    Hey m_c thank you very much for the link I have seen a few schematics with the thermistors in them looking on the web but I haven't ever used one before. Would I need just to include a thermister inline just before the Toroidal Transformer on a PCB and then a connection from there to the Toroidal?

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