Power Supply Issues

[ribuck]

Hi all,

I've been working on my dome project and i hit a snag with a power supply unit, which i'm hoping is just a duff unit.

I bought a 24v 15a swithcing power supply which blew up with a spectacular bang after only a few minutes use, to the point where it dissintegrated the fuse in the power supply and blew it clean out of it's holding clip in the process.

I have a 24v 8.5a dc motor which is being driven by a motor driver which is rated up to 30v & 15amps continuous draw, but also has a peak amp draw rating of up 170amps to compensate when the motor starts etc.

I had it all wired in, and it was working fine, and i was able to start and change the direction of the motor, then after a few mins usage, the fuse on the power supply blew with an almighty bang.

I also double check that the power supply was set to 240v before wiring it up.

all my other items connected at the time of the incident such as the Arduino board, serial port etc are all still working fine, and even though i can't test the motor driver, it does look ok.

Anyone got any idea's of what might cause this ? or is it likley to just be a badly made power supply unit ?

[PhillyDee]

Is the motor trying to take too much power?

If its an eBay special, then its very badly made. If anything it should have just not supplied the power. Send it back!

Oh, and handy chips those Arduino's. I have a Sanguino on my 3D printer.

[ribuck]

Well the motor is rated at 8.6amp @ full draw, and it has a 10amp motor filter on it (Basically a huge capacitor), and the motor driver can supply 15amps continuous (170amps peak) and the power supply is 15am continous.

So tehnically speaking everything is well within limits, so i can only assume it's the cheap ebay special power supply.

[Beyond_Vision]

It might have been down to the peak current being drawn at startup of the motor. Although if it was a decent power supply it should current limit before blowing a fuse. You may need a reservoir capacitor rated above your peak current to supply the motor as it gets going.

Regards

Kevin

[Mikea]

I suspect the poor old switcher was not capable of supplying the repeated surge currents when the motor was started from standstill. The non-moving motor would just look like a dirty great short circuit! What model was the psu?

[Merlin66]

What about a Slo-Blow 15A fuse in the 24V line between the PSU and the motor driver??

May give some protection - the next time!

[ribuck]

The power supply was from ebay, but just noticed it was only a 10amp supply. It worked fine for a while driving the motor then blew.

24V 10A DC Universal Regulated Switching Power Supply on eBay (end time 15-Oct-09 14:32:55 BST)

The motor itself has a 10amp filter on it, essentially a huge capacitor, which should stop and sudden surges, hence why i think arduido etc all survived fine.

The motor driver supports up to 15amps continuous and can handle peak surges of up to 170amps, and filter them out, so it's almost like i have 2 layers of protection form motor startup surge.