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Recommendations for 60V 20+A DC power supply to test RC brushless motors?

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thm_w:
Ah I see yes if the chassis is no longer grounded. I would not want to do that, if possible, keep the chassis grounded and just disconnect the output.
In some cases this can be done. There is a plugpack that I use where they run a green earthing wire from the mains in to output, if you cut that the output is now floating safely.

nctnico:
I'd look for a brand called 'Gophert'. They make a whole range of switching power supplies that are low cost, are of reasonable quality and should cover this application. Likely the (ab)use of old telecom / server power supplies is even more expensive.

james_s:

--- Quote from: Martin72 on October 28, 2022, 10:50:13 pm ---
--- Quote ---I don't really see too much difference in electric shock risk for a grounded 60V server PSU vs a floating output 60V PSU.
--- End quote ---

It starts with the housing itself.
PC-PSUs aren“t made to use them outside the PC.
And they will be switched on/off by the PC.
Cutting off Ground is always a risk factor,  minimum you can get problems with EMI.
To get 60V/20A, you must buy five PC-PSUs, doing the "mod" to connect them together, make them switchable on/off.
Inrush current can be a problem for mains fuses.
Finally no current/voltage limitation....

--- End quote ---


Who cares? This is a bench testing rig, not a consumer appliance.

Surplus server PSUs have been the standard way of powering chargers for RC aircraft for quite a few years now, series pairs of modified PSUs to get 24V are extremely common, never heard of one blowing up. These PSUs are dirt cheap, I have at least 5 of them around here already though I've never tried running all 5 in series. Switching them on is as simple as bridging two terminals. They do in fact have current limiting, or rather overcurrent  protection, they shut off if overloaded. This can be a problem when powering something like a DC motor that has high inrush. Server PSUs are extremely robust, I've been abusing them for years, never had one fail yet.

james_s:

--- Quote from: thm_w on October 28, 2022, 10:58:28 pm ---Ah I see yes if the chassis is no longer grounded. I would not want to do that, if possible, keep the chassis grounded and just disconnect the output.
In some cases this can be done. There is a plugpack that I use where they run a green earthing wire from the mains in to output, if you cut that the output is now floating safely.

--- End quote ---

Huh? Says who? I lift the DC ground from the chassis, I don't lift the earth ground. The chassis stays safely grounded, only the output is now floating.

james_s:

--- Quote from: tautech on October 28, 2022, 10:42:30 pm ---Probably but you first need check the manufacturers ratings of how far their outputs can be elevated above mains ground which applies when using multiple units in series.

--- End quote ---

The manufacture will tell you 0V, because from the factory the output ground is tied to earth. In many cases they are easily modified to change this though. When playing around with cheap surplus stuff the easiest way to find out is to just try it, if it fails, scrap it and start over with something else.

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