Using individual PSUs for each driver
Hello - I saw a 3-axis CNC machine yesterday that had 4 separate PSUs, all the same values. One for each driver, then another for the board. Each of these PSUs has 3 channels but only one is being used.
It seemed extremely wasteful to me, but the engineer who made the machine (they sell them) said there's two reasons for it:
1. It's easier for them to identify and service problems when a driver goes out. I have never heard of a single channel on a switching PSU going out without the others going out (correct me if I'm wrong, I'm no expert), so it would seem to me that point is of no benefit to them.
2. When there's a lot of stress/load as the machine works, spikes in amperage use can cause interference/missing steps, etc. As far as I knew, as long as your amperage had a little overhead for the maximum usage of the drivers and board, you'd be all set.
I did a little research and saw a couple people ratifying the second point there, but it wasn't specific enough for me to say whether or not it's a justified move to stock a machine with 4 PSUs when a single multi-channel, high amperage one would do the trick. I don't know enough about active/passive supplies, or electrical engineering in general to say this is all silly, so I come to you people. Is this actually a good idea? It seems like no money is being saved and there's no benefit to the company or the customer..
Re: Using individual PSUs for each driver
With regard to point number 1.
You just junk the 1 psu on that particular driver.
The initial cost of 4 small supplies vs 1 large supply is relative but.....
In the future..... Replacing 1 small one is cheaper than replacing a large one.
Switched psu outputs are in parallel so if one goes they all go.
It's just so you can get all the wires you potentially need to attached to it.
Mine has 4 supplies in it.
80v for Z & C. (future plan for c)
60v for X & Y.
24v for main control boards / relays / sensors / servo driver.
5v for controller itself / LPT I/O ports to control boards + step/dir etc.
Re: Using individual PSUs for each driver
Quote:
Originally Posted by
jtb00
Hello - I saw a 3-axis CNC machine yesterday that had 4 separate PSUs, all the same values. One for each driver, then another for the board. Each of these PSUs has 3 channels but only one is being used.
It seemed extremely wasteful to me, but the engineer who made the machine (they sell them) said there's two reasons for it:
1. It's easier for them to identify and service problems when a driver goes out. I have never heard of a single channel on a switching PSU going out without the others going out (correct me if I'm wrong, I'm no expert), so it would seem to me that point is of no benefit to them.
2. When there's a lot of stress/load as the machine works, spikes in amperage use can cause interference/missing steps, etc. As far as I knew, as long as your amperage had a little overhead for the maximum usage of the drivers and board, you'd be all set.
I did a little research and saw a couple people ratifying the second point there, but it wasn't specific enough for me to say whether or not it's a justified move to stock a machine with 4 PSUs when a single multi-channel, high amperage one would do the trick. I don't know enough about active/passive supplies, or electrical engineering in general to say this is all silly, so I come to you people. Is this actually a good idea? It seems like no money is being saved and there's no benefit to the company or the customer..
I'm with you on this there should only be one Power supply, there is no electrical reason to use more than (1) power supply, there is a reason why they do this though, and it is cost (3) lower watt Power Supplies are cheaper than (1) large one, ( about a $20 to $30 saving) when you get back to basics (1) Toroidal Power Transformer with all the voltage taps you need and each output regulated you can't beat it, SMPS advantage is low inrush current on start up, but no other advantage, both types have their place
SMPS create a lot of interference (EMI) as soon as they are turned on, it is there all the time, no different when it is loaded that is just Bs :)
