UPS sizing

[Microwatt]

Wiring up for some new lab equipment. The suppliers of the equipment recommend (in the US) a 5200VA UPS to support the equipment. They recommend a 3600VA UPS for the same equipment in the UK. The purchasers of the equipment are asking me if a 3600VA UPS will do it. I responded that we should go by their recommendations.

My first question is, "Is the UK 50Hz?" My next one is, "Is that the reason for the lower VA rating?", since inductive reactance is directly proportional to frequency. Or, am I way off?

 

[skeshesh]

I'm not familiar with the UK system much, but from what little I read about it a while ago I believe their distribution end voltage is around 220-230V. It is surprising that it requires a lower VA rating. Would love to hear an answer from the experts. Would be great to hear from Besoeker since, not only he's experienced and knowledgeable, he's from the UK.

 

[dbuckley]

Can confirm the UK is definitely 50Hz.

But I've never seen a requirement of size of UPS change by that amount for different countries. I too would like to know why. Can you be more spoecific about the bit of equipment?

 

[Microwatt]

UPS sizing

It's a mass spectrometer.

 

[masterinbama]

I was taught that watts are watts. Changing the voltage does not change the consumption of energy.

 

[skeshesh]

I was taught that watts are watts. Changing the voltage does not change the consumption of energy.

I was thinking about current draw rather than power consumption, but you may be right if its rated for US use should be about the same amount of power. I know what a mass spectrometer is but I don't know the inner workings - does it have components that cause high impedance and can possibly effect the performence when the frequency of operation changes? I dunno just throwing ideas out there really...

 

[drbond24]

Wiring up for some new lab equipment. The suppliers of the equipment recommend (in the US) a 5200VA UPS to support the equipment. They recommend a 3600VA UPS for the same equipment in the UK. The purchasers of the equipment are asking me if a 3600VA UPS will do it. I responded that we should go by their recommendations.

My first question is, "Is the UK 50Hz?" My next one is, "Is that the reason for the lower VA rating?", since inductive reactance is directly proportional to frequency. Or, am I way off?

The only way that makes any sense is if they are providing a different piece of equipment to the UK. A device will use the same amount of power regardless of its geographic location. If the voltage is different then the current will be different and the total power consumed will be the same. If the equipment is really the same for here and the UK then the recommendation for UPS should be the same. It won't need more here (US).

 

[Microwatt]

does it have components that cause high impedance and can possibly effect the performence when the frequency of operation changes? I dunno just throwing ideas out there really...

There is a small vacuum pump with it.

 

[Besoeker]

I'm not familiar with the UK system much, but from what little I read about it a while ago I believe their distribution end voltage is around 220-230V. It is surprising that it requires a lower VA rating. Would love to hear an answer from the experts. Would be great to hear from Besoeker since, not only he's experienced and knowledgeable, he's from the UK.

Experienced = old. So that at least fits.
Yes, UK is 50Hz. LV distribution is 400V 3ph/230V single phase.
But I'm with the others here. I see no sound technical reason for such or any difference in UPS capacity.
Maybe it's an FDA requirement?

 

[skeshesh]

Experienced = old. So that at least fits.

I guess it's the way it goes (time = experience). It's a complement anyway; I don't think there's anything that great about being young, other than I guess I haven't had my hopes and dreams crushed completely as of yet

 

[Besoeker]

I guess it's the way it goes (time = experience). It's a complement anyway

And I very much appreciate the compliment.

 

[myersbw]

Time needed...?

Time needed...?

Hi Microwatt!

I'm figuring you answered this question by now, but I've dealt with desktop support for 23 years and I've been there with that question.

That UPS rating basically will determine a finite period of time that device will operate, thus, the reply to the "bean counters" (who would like to save dollars with the lesser capacity unit) might be..."How long do you need this device operating when the power is lost?" If the lesser capacity device provides that...so be it.

It just doesn't make sense that the 50Hz rating of UK power will vary it enough. The guaranteed output of the device is still what it is designed for with respect to our power supply. It's the only calculation to use. Thus, the number of actively powered minutes of operation after power removal is the only legit question to answer.

All the best!
Brad

 

[Microwatt]

Hi Microwatt!

I'm figuring you answered this question by now, but I've dealt with desktop support for 23 years and I've been there with that question.

That UPS rating basically will determine a finite period of time that device will operate, thus, the reply to the "bean counters" (who would like to save dollars with the lesser capacity unit) might be..."How long do you need this device operating when the power is lost?" If the lesser capacity device provides that...so be it.

It just doesn't make sense that the 50Hz rating of UK power will vary it enough. The guaranteed output of the device is still what it is designed for with respect to our power supply. It's the only calculation to use. Thus, the number of actively powered minutes of operation after power removal is the only legit question to answer.

All the best!
Brad

Actually, this is still a mystery to me. They are close to putting the equipment on-line and when the technician shows up to do it I plan on drilling him. I will update this thread with any findings.

The real weird thing is in the specs., it says they recommend the larger UPS for 110v countries. I wish I could attach the specs. to this thread for all to read, but I don't think they would like that.

 

[Besoeker]

That UPS rating basically will determine a finite period of time that device will operate,

The kVA rating determines what current you can draw at rated voltage. The duration or autonomy is determined by the storage capacity of the cells.
You can't determine autonomy from kVA rating alone.