Generator Maintenance

[normanton]

Hi guys, I'll give you a brief run down of the system before I go into the problem. At the hospital where I work we have two back up generators. They're rated at 750KvA. In the event of mains failure, they both start up same time, one generator will then connect to the main busbars, then roughly 15 seconds later the second generator will synchronise and help take the rest of the load using a load shedding set up on our BMS.
So, here lies the issue at present... Its been brought up that we shouldn't be carrying out maintenance on the generators whilst they are switched on and potentially live. Reason being, if (in the unlikely event) you were to lose mains whilst on top of the generator checking the water, checking the oil, or even checking the battery acid levels, injury could occur. The only solution we have come up with so far is to isolate 1 generator at a time whilst carrying out the maintenance checks. Only problem being, is that one generator alone will not carry the full load of the hospital and would therefore trip out on overload. Unless there is some sort of set up that can be installed on the BMS to prevent this from happening I'm all out of ideas. Any suggestions or anyone else had a similar experience? Look forward to your comments.

 

[Pete999]

Don't you have a load shedding facility where by only essential loads will be supplied by the standby sets> I know it's hospital but there must be some areas that can be shed until the grid is back on allowing you to carry out essential mainenance

 

[plugsandsparks]

I was thinking more about an agreed scheduled maintenance time when load is known to be at its lowest, e.g. at night perhaps Sunday when all ward lights are off and operating theatres are just on emergency as is Xray and all outpatient depts. should be shut. That must get the load down below one Gen set ?

 

[Pete999]

Good idea you could use that scenario along with the one I described, job done

 

[normanton]

Yes good idea about waiting until the load is assumed to be at its lowest. Our load shedding brings on the critical areas first, ie, Theatres, SBCU, ITU, then slowly brings in other areas. Thanks guys

 

[plugsandsparks]

A load tester could be useful here, put in on Friday morning and go back Monday afternoon. that should give a nice profile for you to work against.

 

[snowhead]

This is a Hospital being talked about with life critical services, asking for a solution to a serious potential problem on the Internet should not be necessary.

The problem of running on only 1 generator should already have been sorted out in case 1 of the 2 generators fails in service.

Something is not right with the Electrical Engineering Management in this Hospital.

 

[Robotstar5]

You really should have spare capacity, I've not been involved in generators but did have a similar set-up at a factory for the air compressors where we had 5 compressors. 2 ran constantly while the 3rd made up any shortfall, the 4th was on standby while the 5th was isolated for maintenance.

 

[egg67]

I think that when the gens where first installed someone would have put a maintenance in place for gens as what day and time you can do it, also i think you need to update your profile as from that you work for Virgin Media not NHS, not having a go but it does look a bit if

 

[Knobhead]

The obvious people to ask are the design team and the generator manufacturers not a bunch of random guys on the internet.
There’s a lot more to gen-set maintenance than a cursory quick check of oil and water.

But you would know these things if you were actually in a position to make any decisions.

2 x 750KVA sets is very small for a hospital with a surgical unit. Added to which redundancy would be built in to the backup system.

You don’t just happen to go under the pseudonym “Walter Mitty” do you?

 

[PEG]

I think that when the gens where first installed someone would have put a maintenance in place for gens as what day and time you can do it, also i think you need to update your profile as from that you work for Virgin Media not NHS, not having a go but it does look a bit if

...Still might work for Virgin...last time i visited someone in hospital,the largest item/expenditure was the "multi-media" TV above each bed....Genys probably run THAT dedicated circuit...

 

[Brightspark2]

I'm surprised that it hasn't been designed so that one generator can take the full load...

On sites I work they bring in temporary generators while the main generators are serviced/maintained...I'm not suggesting, just mentioning...

 

[High Tower]

1500 kva combined is no where near enough for a hospital surely, we've just been enclosed in putting in a 1000kva for a warehouse, a big one at that I have to say, but just a warehouse all the same

 

[egg67]

at least virgin will fix it within 5 working day so no one will ???????????????

 

[Engineer54]

No, you shouldn't be undertaking any maintenance work on generators that are in a ''Stand-by'' condition, they need to be fully isolated from the system... Not sure why you are coming here asking to be honest, this should all be part and parcel of hospital H&S procedures. I can't see those procedures allowing you to work on anything, that that isn't completely isolated from the supply...

For a start, you don't usually have paired generators starting, one then connecting to the main switchboard then waiting for the second to synchronize, paired generators should start, then synchronize, BEFORE taking up the load. Also sounds as if your main switchboard hasn't been sectionalised very well either, or have the ability to further shed load, in the event of the second generator not being able to sync, or trips out for other reasons. Either that, or the hospitals BMS hasn't been programmed very well.

What size distribution transformer(s) supplies your main switchboard...

 

[Engineer54]

1500 kva combined is no where near enough for a hospital surely, we've just been enclosed in putting in a 1000kva for a warehouse, a big one at that I have to say, but just a warehouse all the same

Could be quite a small hospital or part of a hospital with a small essential load requirement. It's why i asked for the TX size(s) that are supplying the buildings switchboard.

Our hospital buildings each have 1600KVA paired standby gensets, but then we have 3 separate hospital buildings and several other medical buildings, housing clinics and out patients etc...