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  1. #101
    For the record it also lists overcurrent protection. If you're after the input rating it's 20-70VAC and 30-100VDC. Is that what you were looking for?
    If you are just going to put AC in then I would not go more that 60V AC as the mains can and does fluctuate.
    ..Clive
    The more you know, The better you know, How little you know

  2. #102
    Quote Originally Posted by Clive S View Post
    If you are just going to put AC in then I would not go more that 60V AC as the mains can and does fluctuate.
    This ^^^^^

    Mains electricity is very ďdirtyĒ in some areas. Stick a scope on the mains and you would be shocked to see how bad it is at times. Itís the reason if it was me I would at least have a voltage regulator in the circuit at the very minimum. Cleans up that dirty power a treat.

  3. #103
    Quote Originally Posted by Juranovich View Post
    would I run the risk of overheating my drives/steppers with this setup? The drives I've been offered (Lichuan LCDA86H) do list "overvoltage protection", but this sounds to me more like a fuse type protection than active voltage regulation.
    Do not rely on the OV protection of these drives, they will not save you from more than just a few volts. So if you get a spike then they will fry them.
    They are good drives provided you leave a good safety margin.

    You need to leave at least a 10% safety margin on the voltage and I wouldn't run much above 60Vac with 70Vac Max.

    Regards the Transformer I use 750Va with these drives without any issues. I wouldn't go above 750Va because you will get troubles from inrush.

    Do NOT use a regulated PSU like as been suggested by one member as it could cause you troubles with voltage clamping.

  4. #104
    I keep meaning to ask, do you guys use surge protection or, better yet , run it through a UPS to clean the mains transients from glitching out the machine and computer. I’m wondering if a domestic surge protection device would freak out. I seem to have this memory of a computer with a beast of a psu that kept freaking out because of the surge protector (think it was 1200w psu because of all the extra stuff he was using including a crazy raid array and loads of RGB). Once he ditched the surge protection the machine worked fine.

    That’s why I’m thinking a decent UPS would at least let you shut down safely. Or is my OCD going overboard again?

  5. #105
    Quote Originally Posted by NeoMorph View Post
    This ^^^^^

    Mains electricity is very ďdirtyĒ in some areas. Stick a scope on the mains and you would be shocked to see how bad it is at times. Itís the reason if it was me I would at least have a voltage regulator in the circuit at the very minimum. Cleans up that dirty power a treat.
    What are you on about You can supply a drive with a toroidal, rectifier and some caps ie DC or just use a toroidal and use the rectifier and caps in the drive.

    Thatís why Iím thinking a decent UPS would at least let you shut down safely. Or is my OCD going overboard again?
    I think you are going overboard a bit here and frightening new users into things they just don't need
    ..Clive
    The more you know, The better you know, How little you know

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  7. #106
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 7 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,664. Received thanks 292 times, giving thanks to others 10 times.
    The fact that the drives are rated at "20V-70V" AC in is a pretty clear indication that they are very tolerant of input voltage variations. The only thing that really worries them is input overvoltage, which is why Jazz has suggested aiming at about 10% under the nominal maximum to give a bit of headroom for the odd spike, mains surge, etc. There is no point in cleaning up the raw AC input to the drives. These devices are power switching to motors, not audio amplifiers! I hung a 'scope off the DC supply to my drivers some time ago and saw something like a 10V 100Hz ripple across the smoothing caps and the drivers clearly weren't worried about that - they've been working for a few years now quite happily. There are things that need close attention, like good earthing techniques, keeping noise-producing high power cables away from low-level sensitive feeds to inputs, but the basic supply to the drivers can be pretty crude by comparison. In fact, a simple linear power supply will beat the pants off a switched-mode supply when it comes to feeding stepper drivers as you have to drastically over-spec the SMPS to cope with the odd peak load which causes it to go into shutdown or some other protective mode where the linear supply just dips a bit and carries on.

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  9. #107
    Quote Originally Posted by Clive S View Post
    What are you on about You can supply a drive with a toroidal, rectifier and some caps ie DC or just use a toroidal and use the rectifier and caps in the drive.



    I think you are going overboard a bit here and frightening new users into things they just don't need
    No no no, Iím asking the question of experienced users. Iíve only got experience of an openbuilds machine at present and havenít had the pleasure of building a larger CNC so the opís question and your reply about mains fluctuations made me think about running tests on the local power grid.

    I canít remember the figures from my last test but I do have the kit still.

    I still remember the time back in Cannock where I was sitting in offices and suddenly the ceiling fans turned into scary propellers. Turned out the distribution centre had supplied twice the rated frequency for a while... blew a ton of mainframe terminals throughout the building and only the fact that it tripped the generators protected the two mainframes we had downstairs (IBM 370/158 and IBM 3033).

    That truly is a worst case scenario but check your local power. Mine is ruddy awful at times, especially around 6pm. My oven is flashing the clock timer at me because we had a brownout yesterday.

    But ultimately I donít know much about mains system and I havenít touched anything 3 phase or high voltage this millennium... so Iím very much the noob asking questions.

  10. #108
    From what Neale said made me do a facepalm... not at him, at me. Of course the driver will clean it up. Iím a moron.


    Sent from my iPhone using Tapatalk

  11. #109
    Quote Originally Posted by Neale View Post
    but the basic supply to the drivers can be pretty crude by comparison. In fact, a simple linear power supply will beat the pants off a switched-mode supply when it comes to feeding stepper drivers as you have to drastically over-spec the SMPS to cope with the odd peak load which causes it to go into shutdown or some other protective mode where the linear supply just dips a bit and carries on.
    Neale is 100% spot on and using an SMPS is asking for trouble because at some point it will bite you when it goes into protection mode. KISS works for CNC no need for over complicating the job with Surge protectors or UPS, DHL, FedEx or any other courier service...

    Now back to these drives and the Question of AC or DC. I've used these drives with both AC & DC and in terms of performance, I've seen no differences.
    However, I've never run them on machines working in harsh conditions regards power fluctuations, etc but I suspect that if the mains supply was prone to fluctuations or was a little dirty then using a DC supply would be less stressful on the drives due to larger Caps being more capable of smoothing out the power than the little caps that will be used on the individual drives.

    Now I'm not into electronics so I don't know if when using a DC supply the drives still use their onboard Caps as extra smoothing.? . . my gut says they probably do.!

    But that said I would always go with the simple approach if normal conditions so AC is easier and cheaper. The machine doesn't care if you run it on Everyready battery's so long as it gets a nice supply of power when it asks for it.

  12. #110
    Kitwn's Avatar
    Lives in Don, Tasmania, Australia. Last Activity: 2 Weeks Ago Has been a member for 4-5 years. Has a total post count of 976. Received thanks 115 times, giving thanks to others 52 times. Referred 1 members to the community.
    Quote Originally Posted by JAZZCNC View Post
    Now I'm not into electronics so I don't know if when using a DC supply the drives still use their onboard Caps as extra smoothing.? . . my gut says they probably do.!
    If they use the same input connections for DC as AC as I assume they do then the rectifier and capacitors must still be in the circuit.

    One other thing to consider: If you add an additional rectifier and capacitors to make a DC supply for an AC driver you will also increase the inrush current to the transformer and increase the risk of trips. Adding more capacitance for the sake of it to any DC supply (making Neale's audio amp PSU instead of a motor driver one) will have the same effect.
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

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