topic Re: UPS load in Servers - General

UPS load

George Doller — Tue, 25 Mar 2003 20:16:08 GMT

I wanted to know if there is anyway to get the current % of load on my ups's without installing the upsmanager II sw. I did install it, but I wasn't able to figure out the configuration. I was trying to use the serial port and got no communication. I am just trying to find out how much more equipment I can load onto my current ups's.
thanks

Re: UPS load

Chris Vail — Tue, 25 Mar 2003 20:25:49 GMT

Without installing and using the UPS's management software, the only way to measure current draw is with an ammeter. This device is available at almost any electrical supply house, and consists of a spring-loaded loop that can be opened, placed around a power cord, and closed. The amperage can then be read on the meter. The formula is POWER in watts is equal to AMPS times volts. So a 2 amp reading for a 120 volt circuit means that the system is drawing 240 watts. UPS's are rated in watts. In this case, a UPS that is rated to hold up a 1200 watt for 10 minutes will (in theory) hold up a 240 watt load for 50 minutes. Don't bet the rent money on this, however.

Chris

Re: UPS load

Steven E. Protter — Tue, 25 Mar 2003 20:31:04 GMT

You can look at the power supply for everything connected to the UPS and add up the load.

If its HP hardware you can look up electrical specs on hp's web site.

Add the figures up and you'll know if you have an issue.

SEP

Re: UPS load

Leif Halvarsson_2 — Tue, 25 Mar 2003 20:58:22 GMT

Hi,
The best metod is to use a DC Clamp-on amperemeter on the accu cords and divide the the ampere reading with the capacity of the accu. Before doing this you should disconnect the UPS from the main. Don't rely to much on AC measurings on inductive loads if you don't know the power factor (cos. phi).

Re: UPS load

Wim Rombauts — Wed, 26 Mar 2003 08:05:00 GMT

What king of UPS are you using ?

Some UPS systems have a LED indicator that gives a rough estimate of the load.
On our Powertrust-II UPS systems, the load is indicated with 4 LED's at the front. It is not very precise, but good enough to know if it is safe to connect a lot more equipment or not.

Re: UPS load

George Doller — Wed, 26 Mar 2003 16:12:21 GMT

I have 2 powertrust II -MR 6.5kW (9kVA) UPS 230V and 1 5.5 KVA powertrust. The 6.5 has the lights and all 4 lights are on, but I find it hard to believe I'm using all that it can handle. I will try to add up the usage.

Re: UPS load

Tony Willis_1 — Wed, 26 Mar 2003 16:21:02 GMT

The current meter that opens to allow access around the ac cables is the true measure.
The figures that HP supplies are so conserative that the US Military dies there own measurements. HP measured specifications have been off by as much as 40%.

UPS Man II does not supply all the features that HP was led to believe.
If, you are using a powerTrust prior to2003, read paragraph 1 above.

Personally, I found that APC tells you everything and its abilities through software are superior.

You are better off using a THIRD PARTY Power Software Manager with the Exide/PowerTrust units that UPS Manager II.

Tony

Re: UPS load

Seth Parker — Wed, 26 Mar 2003 16:25:14 GMT

George,

We have a similar PowerTrust II MR UPS and the LEDs you're describing are showing you the charge on the batteries. You have to press the right-most button to see the load. (Hehe, read the button label first to make sure it's not different from mine!)

Seth

Re: UPS load

George Doller — Thu, 27 Mar 2003 14:02:59 GMT

Could someone give me the "current meter" brand and model number that a few of you are talking about. Some one told me that it is not as easy as just putting the meter around the cable. maybe they are using a different meter.