UPS for Radiology Equipment

[anbm]

We have one CT and one RAD equipment, owners want to feed both of these from an UPS (the UPS is downstream of our panel),
owner asked us to size the UPS to support these two equipments.

From radiology vendor drawings, it shows maximum load for CT is 60kW and RAD is 126kW.

Correct me if I am wrong, size there is no specific rule to size UPS in this case, I used NEC-517.73(2) as a go-by:

Largest radiology at 50% its max load = (126x 0.5) = 63kW
Second largest radiology lat 25% mits ax. load = (60 x 0.25) = 15kW

So, UPS size may need = (63kW + 15kW) = 78kW?

 

[iwire]

I would not move forward without talking to the UPS manufacturer and the medical equipment manufacturer.

 

[iMuse97]

I would not move forward without talking to the UPS manufacturer and the medical equipment manufacturer.

Bob is right. If your UPS is sized as you suggest with demand factors, you will need to be sure that the UPS can handle the power demand if it sees the load when both machines peak at the same moment and that happens to be the moment of power transfer to the battery source in the UPS.

 

[iwire]

you will need to be sure that the UPS can handle the power demand if it sees the load when both machines peak at the same moment and that happens to be the moment of power transfer to the battery source in the UPS.

Inrush is exactly what I was thinking of, as far as I know standard UPS units don't have a lot of head room for inrush.

 

[anbm]

This UPS is fed out of a panel (the panel is fed out of ats)

The building has generator and this UPS will pick up power within 10 second when building lose utility power and before generator starts.

Will this make any difference?

 

[iMuse97]

Certainly the batteries will not have to last long; however, they will still have to me inrush current and/or max. load currents mentioned in previous posts. You still will have to contact the equipment and UPS manufacturers, IMO.

 

[Mike01]

UPS Solutions

UPS Solutions

This UPS is fed out of a panel (the panel is fed out of ats)

I would also suggest talking to the ups manufacturer, as step one. On another note depending on the application keep in mind the weight of the batteries and structural implications if the equipment is not located on the first floor. Another alternative to batteries is an inertia based DC source like a flywheel in my opinion a more reliable source, seeing that one bad cell and the string could be down. As you indicated in an earlier post the equipment is backed up by a generator so the ride thru would be minimal in time. The flywheel will only provide seconds (approx. 10-45 depending on the size) but should be adequate until the generator starts, the advantage is the design life is about 20 years with minimal maintenance, whereas the batteries will have to be replaced every 3-5 years, and the flywheel provides better inrush capabilities than the batteries, also the flywheels are significatly lighter. The downside the initial cost is significantly more than batteries but when looking at all the other implications (structural, battery replacement, possibly hydrogen detection) it may prove more cost effective, also if the facility is looking to tell a sustainable story the flywheel is much "greener" than a battery solution, without the disposals, lead, etc. Just a thought.

 

[anbm]

I would also suggest talking to the ups manufacturer, as step one. On another note depending on the application keep in mind the weight of the batteries and structural implications if the equipment is not located on the first floor. Another alternative to batteries is an inertia based DC source like a flywheel in my opinion a more reliable source, seeing that one bad cell and the string could be down. As you indicated in an earlier post the equipment is backed up by a generator so the ride thru would be minimal in time. The flywheel will only provide seconds (approx. 10-45 depending on the size) but should be adequate until the generator starts, the advantage is the design life is about 20 years with minimal maintenance, whereas the batteries will have to be replaced every 3-5 years, and the flywheel provides better inrush capabilities than the batteries, also the flywheels are significatly lighter. The downside the initial cost is significantly more than batteries but when looking at all the other implications (structural, battery replacement, possibly hydrogen detection) it may prove more cost effective, also if the facility is looking to tell a sustainable story the flywheel is much "greener" than a battery solution, without the disposals, lead, etc. Just a thought.

Thanks for response. Another question, do we size the generator big enough to support UPS size or...
size it according to NEC-517.73(2) - demand load?

 

[Mike01]

Gen Size

Gen Size

You have to look and see what the UPS MFGR recommends and it really depends on the size of the Gen. but if you have a smaller generator you may need to increase it in size for the UPS block load, unless the ups has a walk-in or soft load feature, but the overall generator size should be sized to accomodated the UPS, and its charasterstics.