HP 3458A on a "Pure Sinewave" UPS

[Tony_G]

Hey All,

I'm just wondering if there is any issue with putting my 3458A on a UPS? I wanted to keep the PC that I'm using to record data from my 732A up if a power outage occurs and I'm wondering if I should just keep the 3458A on it as well?

Does anyone have experience with doing this?

Thanks,

TonyG

[KT88]

Since UPSs use  switched power stage s it won‘t be the cleanest supply voltage. Although you could use it detached from mains there is still some HF common mode noise to ne expected.

[bdunham7]

The only issue I've had with my APC SMT1500 UPS is that the small amount of conducted noise that it has interfered with the noise floor on my Fluke 8506A in the lowest AC ranges.  I now have it set up so that I can take it out of the picture (which requires both a shut down and unplugging) reasonably easily.  I haven't seen any effects with 10V references or the meters measuring them.

[johansen]

If its a problem then a 100 watt isolation transformer will fix it.

[J-R]

Some UPS units like the APC SMT1500 (I have a few of the Dell/EMC-branded ones) have a "Green" mode which can be enabled or disabled.  When enabled, the UPS is essentially in bypass mode with most of the electronics powered down and you are connected directly to the wall until there is an event.  When disabled, it operates like a normal double-conversion or AVR or etc. UPS where it essentially is running the inverter all the time and there is no direct connection to the wall, in a manner of speaking (ground is always connected of course).  Also, there is a slightly longer delay before the UPS intervenes when it is in green mode due to the relay switch delay.

I've had most of my equipment on pure sine UPSs for years (in green mode) and haven't ever had any issues, but I can't say I've run any specific tests to see what things look like when the UPS is supplying the power or with green mode disabled.  It probably depends on multiple factors, so running some tests would probably be the best way to determine which is better for you.  I wonder if some filtering could help as well.

[sweaterfluid]

UPSs employ switched power stages, therefore the supply voltage will be less clean. Although it may be used independently of the mains, some HF common mode noise is to be expected.
hill climb racing

[IanJ]

My tuppence worth…….
If you have a UPS that isn’t producing the best sine wave output then look at adding an isolation transformer and an active or passive filter/ line conditioner. You could probably build something quite small if it’s only powering a couple of instruments.

Hmm, might have a go at this myself on my own UPS.

Ian