Earth fault/leakage current tracing

[sparkydude]

Basically this problem must have been present in the past , but there was no SEPAM unit on the old panel. Sorry i meant TNS suppy, Doh.
We have won the contract to do the swap over from new to old panels and re-test/certify the newly extended sub mains leaving the new panels. as all the DB's use HRC fuses as their feed, nothing has ever highlighted it previously . As i said earlier and i am glad to have had it confirmed by you the MRI scanner is a likely candidate so we are most definiteley going to be targeting that as one of the first things.
This is not the only supply to the hospital but one of 4, all the other supplies are on the new parts of the hospital we completed last year, their SEPAM relays are reading 0A , its just this old part of the hospital that is causing issues.

Nick

 

[Engineer54]

So there are 4 other incoming supplies to the hospital, ...I take it then that the OP theatres, X-Ray, MRI facilities are centred on the older part of the hospital then, ie this new TX / switchboard your presently working on??

Are you not getting any input from the Hospital's Engineering Manager in this problem?? He would (should) have an in depth working knowledge of his hospital, and be able to give your company all necessary information to help you isolate/locate possible problem areas...

Did the old fuse switch switchboard not incorporate any protective relays that tripped out the fuse switches on identifying faults in the system ?? Even the older manual fuse switches had solenoid trip function, operated by protection relays!!

Just a thought here, has anyone checked the new switchboards control wiring out, this reading your getting on the SEPAM unit could be from a miss-wiring fault. I can assure you it's not an uncommon occurance. Normally these faults would have shown up during the the clients factory visit for inspection and testing, prior to being delivered. But even then, as all the individual panels are then separated for delivery, reconnection of the control side can get miss-connected, it's happened more than once on my projects... It worth a check anyway....

 

[sparkydude]

Yes thats right, the majority of the new parts have the theatres etc in them but there are the older parts still containing certain departments still remaining . The hospitals engineering manager is not a great deal of help they just trust the reading on the SEPAM and are trusting us to sort it out, I will mention it to the project manager tomorrow and get him to have the SEPAM connections checked to ensure they are correct. None of the old panel had any kind of solenoid trips on them just switchfuses and ACBs on the generator connections.

Thanks again for your help


Nick

 

[Engineer54]

That's the second time i've been told that a Hospital Engineering Manager isn't up to his position!!! Things must really be going down hill in the hospital engineering field is all i can say!!!

That old switchboard must have been cheap as chips when it was installed ...lol!!! What about the bus coupler, was that not automatic either, if there was one that is ...lol!!! Or was the generator sized for the whole of one side of the switchboard containing the essential loads?? ...I hope the new MG LV switchboard is a far cry from that old switchboard set-up, but then being MG it certainly should be!! lol!!!

 

[malcolmsanford]

That's the second time i've been told that a Hospital Engineering Manager isn't up to his position!!! Things must really be going down hill in the hospital engineering field is all i can say!!!

Over the years I have worked with 3 hospital engineers and all of them were ex chief Engineers from the Navy, 2 liked the sauce and the 3rd was a bit of a stickler, but all 3 were top guys, but knew absolutely nothing about electrical engineering.

Strange how even at the top of the food chain like site forman and Clerk of works, you very rarely find an Electrical Engineer running a project, I suppose the electric side is too complicated lol.

Top posts E54,I still go down the line that there are terminations and joints breaking down, would be nice to get a thermal camera on these to just see.

 

[Engineer54]

Over the years I have worked with 3 hospital engineers and all of them were ex chief Engineers from the Navy, 2 liked the sauce and the 3rd was a bit of a stickler, but all 3 were top guys, but knew absolutely nothing about electrical engineering.

Strange how even at the top of the food chain like site forman and Clerk of works, you very rarely find an Electrical Engineer running a project, I suppose the electric side is too complicated lol.

Top posts E54,I still go down the line that there are terminations and joints breaking down, would be nice to get a thermal camera on these to just see.

In my experience The Engineering Managers i've come across have been first rate, be they from a mechanical or an electrical background. All have known there hospitals and plant inside out so to speak... Can't say any of them have been ex services, most have come from industrial backgrounds. Those that didn't have much of an electrical background were sensible enough to recruit an electrical engineering assistant, and vice versa with the electrical biased engineering managers. ...For sure none were fools...lol!!

I agree that this problem doesn't sound like a leakage problem, in the true sense of the term, but rather an earth fault or faults. Which is why i asked if any of the breakers had tripped out on an earth fault , frankly i'm surprised they haven't, Not exactly normal to see ...50 to 70+A returning on the earthing system constantly to the main switchboard.

The thermal imaging exercise is definitly a well worthwhile one, and could well turn up the problem relatively quickly, but i just get a feeling this could well end up, being an extensive search/trace operation, especially if this hospitals electrical system hasn't been looked after or maintained over the years. The older the plant the more maintenance, inspection, and testing time should be allocated. Which is where s good hospital engineering manager comes into his own, ...Knowing his hospital!!

Unfortunately, we don't known the extent and condition of this older section of the hospitals installation. All the usual add-on electrical installations to the original layout, and how they have been integrated, can well be the source of the present problem and can be a nightmare to trace if they have been bodged... lol!!

 

[tes11]

hey sparkydue hows it going i have similar problem at supermarket right now 125A on main earth at main switchboard activating high leakage alarm on new switchboard was wondering how u got on with your problem as it seems very similar to my problem cheers

 

[tes11]

help from all would be much appreciated

 

[sparkydude]

Still working through it currently , we are beginning to swap circuits over from old panel to new next week for the next 3 months so are hoping we will track it down once we have swapped a few over.
Lots of theories floating around, mainly pointing to switch mode power supplies and chiller supplies, but no conclusive proof of anything as yet .

Let me know how you go on as it may help me also Lol

Nick