x-ray machine help

[pc1117]

So ive got a x-ray machine to hook up for a chiropracter. Only name plate on it says
220/240V single phase
50/60hz
Input power 40 kva
Output power 32 kw
It also has a step up transformer with it but is in a 12x12 j-box and has no nameplate or label on it.
Question is 166A seems like a lot for an x-ray machine of this size and how can I tell the size of transformer with no label to figure out breaker size. Thanks for the input!

 

[GoldDigger]

So ive got a x-ray machine to hook up for a chiropracter. Only name plate on it says
220/240V single phase
50/60hz
Input power 40 kva
Output power 32 kw
It also has a step up transformer with it but is in a 12x12 j-box and has no nameplate or label on it.
Question is 166A seems like a lot for an x-ray machine of this size and how can I tell the size of transformer with no label to figure out breaker size. Thanks for the input!

This is a pretty powerful x-ray machine which is probably intended to provide a fairly wide (full torso?) beam.
The 32 kw output compares to on the order of 2-8 kw for x-ray units intended for mechanical inspection of small objects.
But your machine will only be actively producing output for a fraction of a second to a few seconds at most. You need to be able to supply the nameplate calculated amps, just not for a very long time. The power supply in the machine does not have enough energy storage to allow a slow charging period and a very fast discharge. The x-ray tube also has to be allowed to cool down between uses or else will be water cooled to handle continuous or long term usage.

For a diagnostic x-ray, most likely the machine will be operated at at much lower current level most of the time. The less current is pulled from the high-voltage power supply, the correspondingly lower input power will be required.

Hopefully the chiropractor will be qualified in radiation safety to test the unit, and you should never try to test it on your own.

 

[jumper]

I would look at this reference for X-ray equipment, 2011 NEC, as a start:

660.6 Rating of Supply Conductors and Overcurrent
Protection.
(A) Branch-Circuit Conductors. The ampacity of supply
branch-circuit conductors and the overcurrent protective devices
shall not be less than 50 percent of the momentary rating
or 100 percent of the long-time rating, whichever is greater.

 

[iceworm]

...Question is 166A seems like a lot for an x-ray machine of this size and how can I tell the size of transformer with no label to figure out breaker size. ...

Is there any information in the installation manual? I always tend to look there first.

ice

 

[kwired]

Is this some sort of "self contained" equipment or is some equipment company setting it up?

Small hospitals and clinics I have connected this kind of equipment for in the past has always been equipment set up by some supplier that knows about the equipment, and most of my job was to bring them a supply circuit or maybe run some wiring for aux equipment.

X-ray equipment generally does draw a high current for very short duration, and they are often very particular about allowable voltage drop. I am assuming the equipment is sensitive to voltage drop because of this.

Last one I recall connecting required IIRC 1/0 copper conductor yet if you think about total power it draws would probably safely run without ever being a threat of overheating on maybe 10 AWG or even 12 AWG and it was a 480 volt three phase unit. Overcurrent protection was high enough (I think 100 amps) that a larger conductor would still have been needed but for no longer of a duration the load lasted I would still guess a pretty small conductor would have had no serious heating issues.

166 amps is likely the value they want you to base voltage drop calculations on more so than being the load to use for load calculations. Don't forget to make sure that service and/or feeders can supply the required voltage at this current level.

 

[pc1117]

Thanks for all the replys! The machine was bought by the Dr. from another office. She is supposedly qualified to set it up and test it. There is no install manual and everything I've found online doesnt pertain to the actual feeders for it. The manufacturer did say it required 63 amps however I question that as being enough as I was going off the input on the nameplate. Unless he is referring to the 50% short term rating and I could see that if its actually going off the output which would be 133.3 amps. I dont have much for voltage drop as I'll only be going about 30'. Also, I believe the step up transformer is only used for 208v installs to bump voltage the machine requires. I guess I keep second guessing myself because I dont want to rate it too high or too low if there were anything wrong with the machine as it was tested. Thanks again for all the input.

 

[kwired]

I dont have much for voltage drop as I'll only be going about 30'.

That is your branch circuit, what about voltage drop on the service and or feeder(s)? Some of this type of equipment is very particular about total voltage drop and you can't just look at the branch circuit alone. Just something to keep in mind.