More heat than I'm used to

[7rojo7]

I have an 8kVA UPS that gives an output of 2 legs of 115V measured to ground (I'm in Europe), its output enters an 8kVA isolation transformer, its output gives 2 legs of 115V measured to ground.
After about 3 hours of operation some of my equipment is hot enough where it's difficult to keep my hand on it (GENELEC 1030a auto amplified speakers back plate and !!!PRISM Sound Dream ADA8, although the Prism is not as hot as the other) The Prisms are new but I don't remember the Genelecs ever getting this hot and I've had them for ten years. All of my equipment (computers, expansion chassis, DSL router T10/100 hub, FibreChannel Drives) is connected to this power supply and I'm not connected in any way to any other system
Is there something I should check like the quality of the ground in this situation or is it normal for equipment to run hotter when seeing 2 legs of 115 instead of 1 leg of 230. I've been running my gear from smaller UPSs but without an isolation transformer for years and to my understanding there has always been this relationship of 2 legged current and my house ground. At one time I had a problem between a 230V to 115V down transformer and a ground interfacing 230V and 115V equipment together that burned up a 115V surge protecter power strip. But I never understood what caused the problem.
I have some pretty nice gear and don't want to burn it up, everything sounds fantastic though.
Is there something I'm missing, something I should be concerned about?
I've never felt this much heat from my genelecs. Any advice would be welcome
thanks in advance
rojo

[Geoff_T]

Hi

I don't have any good suggestions other than for you to gather up data with serious precision.

Have you measured the voltage coming out of your UPS and feeding the equipment?

Are you 1000% sure you have all the equipment set at the appropriate voltage to match your set up?

Are you providing adequate cooling for your equipment?

Have you a means of measuring temperature (you can purchase relatively cheap temp measuring meters) so that you can compare (accurately) the temperature when running on your UPS versus off the regular power.

Touching with the hand is only a very rough guide!



PS I'm tired and missed the obvious question... Are you sure that your UPS is pushing out an undistorted sine wave?

[7rojo7]

Thanks for the reply, I guess I should have an oscilloscope but I don't, it's on my list of house tech gear to buy, a temperature probe wasn't on my list but now it is. My local understocked electronics store is closed on Monday morning, I'll pick up a temperature probe in the afternoon.
The UPS seems very cool, when I'm not recording live performances I run it in Line Interactive mode and not Inline mode, which is why I have the isolation transformer behind it which is also running cool. They're both high quality and normally they're only running at 20% so I wouldn't guess that there's a strain on that system. The Genelecs wouldn't have a problem with their ventilation as they're suspended in shock mounted cages in the open air. All of my tube gear or multicahnnel mic pres have 1 rack space distance between each unit but my converters don't. My space is air conditioned so its not an ambience problem.
I'll report on what I found the problem to be when and if I find it.
Any other sugggestion would be appreciated

[tINY]

My first guess would be output waveform of that UPS. If there is a marked diffence in the PS temperature between running off the grid and running through the UPS.

There are two likely candidates: Peak voltage and harmonics.

If the UPS is rated for an RMS voltage, it may well put out exactly that RMS voltage with a higher peak voltage value. If your linear power supplies are lightly loaded for the amount of bulk capacitance (like nearly all high-quality audio gear), then the unregulated voltage will follow the peak value rather than the RMS value. If the unregulated value is higher, the regulators will be dissapating more power the drop the voltage to the regulated output.

If the UPS is putting out a lot of switching noise (the filters after the PWM aren't so hot), then the transformers in your PS's could be getting hot. The iron transformers tend to dissipate the higher frequencies as heat because they are, essentially, a big inductor.

The last thing you might look at is the frequency output of the UPS. There may be PI filters at the front end of the power supplies tuned for 50 or 60 Hz. If the UPS supplies a different frequency, this could make the filters dissipate a lot of power. (I actually had a spike/surge protector blow up in europe that was designed for 60 Hz when we were running 50Hz off of a step-down transformer).


-tINY