Hospital Power System

Rather depends on how big the hospital is. In the UK at least at one extreme, on a large sprawling campus like a City general hospital there may be many buildings and transformers and an HV ring arrangement is common for a large site, with options to link out sections or to provide LV link feeds such that any one HV/LV transformer may be taken out of service with minimal disruption. Backup generation may also be CHP and may have option to backfeed up onto the HV ring.

Smaller sites "cottage hospital" will be fed at LV and have a simple backup generator, and depending what is performed there, that may only cover a limited set of facilities.

Within the buildings lights and power will be separated by zones, again to allow any one failure to have minimum effect. There are some very specific rules for supplies to areas that do surgery, where the normal levels of touch voltage would be unacceptably high, and a power cut could be very serious indeed.

To add to that, there are specific requirements for areas such as ICU (Intensive care units) which state how many sockets per bed, how many of these are to be uninterruptible, etc.

I think there will also be differences between UK, Europe and Russia due to different distribution systems so there will never be a 'one size fits all' scenario.

Can you tell me more about how lighting and power is separated by zones? Typically how much redundancy and N+X or N-X is observed?

What about grouping of the automatic transfer switches? How do branches need to be subdivided or grouped?


I know I keep asking, but any example single lines? Or of Primary, Secondary and Territary?


Why is territary power needed if the medical equipment has backup batteries? 


Excellent replies btw :)

Link to  Health_tech_memo_0601 to give some bed time reading to those who have trouble sleeping. There are some example wiring diagrams in it, but they are simplified to show the principles, it is not a design manual.

A quote from 0601 for the definition of tertiary in this context. You rather hope not to need tertiary power for longer than it takes to get the backup genset spinning or to make things safe and initiate alternate arrangements, it is only a time limited 'stop-gap' .

"The tertiary power supplies considered are:
• batteries for UPS systems, inverter units and generators;
• HV/LV tripping/closing batteries;
• UPS systems;
• inverter units for central battery units and theatre operating lights "

ProMbrooke:

What about grouping of the automatic transfer switches? How do branches need to be subdivided or grouped?


I know I keep asking, but any example single lines? Or of Primary, Secondary and Territary?


Why is territary power needed if the medical equipment has backup batteries? 


Excellent replies btw :)

There are "typical" UK biased SLD's in HTM 06-01   -  take a look, but note they are very high level to demonstrate the type of load supplied from the type of system


Even if a particular piece of kit (BiPap pump as an example) has integral batteries, you probably want to save those until it's last ditch and you are moving the patient - until you reach that point, the healthcare environment needs to provide the support - hence the tertiary systems that will ride you through engagement with your secondary power systems (many clinical applications have defined allowable break times)


As I said, read HTM 06-01 first, that should give you a good understanding.


Is this just curiosity, or are you planning on embarking on a design ?


Regards


OMS

Thank you- big help.


It looks like everything is simply replicated by at least two? And no mandate on how many transfer switches (at minimum) is required?

OMS:

ProMbrooke:

What about grouping of the automatic transfer switches? How do branches need to be subdivided or grouped?


I know I keep asking, but any example single lines? Or of Primary, Secondary and Territary?


Why is territary power needed if the medical equipment has backup batteries? 


Excellent replies btw :)

 

There are "typical" UK biased SLD's in HTM 06-01   -  take a look, but note they are very high level to demonstrate the type of load supplied from the type of system


Even if a particular piece of kit (BiPap pump as an example) has integral batteries, you probably want to save those until it's last ditch and you are moving the patient - until you reach that point, the healthcare environment needs to provide the support - hence the tertiary systems that will ride you through engagement with your secondary power systems (many clinical applications have defined allowable break times)


As I said, read HTM 06-01 first, that should give you a good understanding.


Is this just curiosity, or are you planning on embarking on a design ?


Regards


OMS




 

 

If wondering here is why I ask. In the US hospitals by code are required to have an essential electrical system and it must be divided into 3 branches. Over 150kva it also must have a minimum of 3 automatic transfer switches.


The branches are:


1) Life safety


2) Critical


3) Equipment


Life safety is required to feed exit signs; emergency lighting in hallways, stairwells, points of egress; evacuation speakers; fire alarms and med gas alarming systems, automatic doors used in evacuation, elevator cab lights and lighting/outlets at generator and ATS locations... basically what is required to contain and evacuate occupants from a burning building.


Critical feeds patient room lighting, patient bed outlets, ORs, blood and bone banks, pharmacy dispencing machines, task illumination... basically anything essential to patient care and life support.


Equipment feeds HVAC equipment, elevators, pumps, medical gas equipment... anything that is needed in the continuation of basic medical care but not immediately vital.


UPS or a teritary system is not mandated by code and only found in some newer hospitals seen when feeding IT equipment, MRIs, ect.


Code requires that critical care areas have a certain percentage receptacles on normal power (typically 1/3 the outlets at a patient bed location, OR, ICU, ect)  and that some level of lighting is connected to the normal branch. The idea is that if the critical branch fails during the presence of utility power, the area will not be blacked out. If more than one critical ATS exists then a critical care area can be fed from both branches and normal power is not required.





Here is an example single line diagram:

Note sure why the pics didn't go through... let me try again: