EBME Forums Forums Maintenance Technical Assistance Endoscopy system installed on medical pendant

Need all expert to advice and thanks in advance.
Do I need to have a isolation transformer if the individual equipment in my endoscopy system meets IEC60601-1 standards. In addition, they are all plugged to individual power socket on the pendant with 10mA RCCB.
I understand that for Endoscopy system installed on mobile trolley with ganged-socket an isolation transformer is required on the trolley so that the leakage current is keep within safe limit.

It's good that your equipment meets IEC60601-1, but what really matters here is the practicality of the situation.

Are you wondering if each item of equipment needs an isolating transformer ...?

Can we assume that the pendant you mention is in an operating theatre?

Is the pendant part of an isolated power system? Is there a LIM (what does it tell you)?

The RCCB(s) won't offer much protection against high leakage current(s), but rather against equipment faults (short to earth, etc.). But having said that, 10 mA sounds a bit low to me. After all, the main reason (these days) for an isolated power system is to prevent power interruptions (even in the event of "minor" equipment faults).

Where are you using the "system installed on mobile trolley"? Outside of the OR? You may or may not need an isolating transformer - it all depends on the total leakage current the system delivers.

How many items of equipment in the "system" on the trolley? Which items are they?

Lastly, how good is the electrical system in general where you are? Can you rely on decent earths, for example? And is neutral connected to earth - or floating about at some other level?

In short - more information required!

Geoff, thank you for the reply.
1) I am wondering if I should connect all the endoscopy system equipment, ie CCU, lightsource, CO2 insufflator and flush pump, needs to be connected to a isolation transformer if they are all from the same electrical power circuit.
2) the pendant is in a Endo procedure suite not in operating theatre
3) The pendant is having a grounded power supply not isolation power supply. Would you consider a Endoscopy suite wet location like operating theatre?
4)When you say the RCCB is a bit low, do you mean it is not sensitive to prevent a leakage current fault?
5)We were using the isolation transformer on the trolley because we were using non-medical grade video recording system with the endoscopy system.
5)This site is a new endoscopy center so the power system has just passed commissioning and it is a grounded system.

OK, so we are talking about a normal (grounded) electrical system.

As it's a brand new system that has just been commissioned maybe it's a bit late to second-guess the designers' solutions!

But back to the 10 mA RCCB(s). Where is this (are these) actually in circuit? I read your earlier post to mean one for each power outlet on the pendant.

Are you saying (as I think you are) that each item of equipment is plugged in to a separate power outlet on the pendant? Or are you using the trolley (complete with isolation transformer) in the Endo suite - and just plugging in the cable from the ganged connector on the trolley to a single outlet on the pendant? Let's be specific here.

With regard to the trolley - I would prefer a "medical grade" video recorder; otherwise I had better let others on here give you "chapter and verse" on that one.

An isolating transformer is not required it is only needed if the sum of the leakage currents is more than the acceptable limit as only one plug is connecting it to the mains supply. In this case all the equipment together is treated like a single item because of the single plug.
When the system is connected to a pendant each piece of equipment has its own supply so they are treated as individual pieces of equipment. Assuming each piece of equipment has a leakage current within limits there is no need of an isolating transformer.
Robert

See also this earlier thread.

Thank you, Geoff and RoJo!

Geoff,
1)Where is this (are these) actually in circuit?
I understand each electrical circuit with 10mA RCCB are connected to 5 power outlet on the pendant.
2)Let's be specific here
Yes, Geoff you are right the individual equipment is plug to each power outlet.

Without an opportunity to take a look at the circuit (diagram) I can't be sure ... but from what you're saying I can't see the point of those 10 mA RCCBs. Moreover, I would anticipate that the only "service" they'll perform will be the amount of "nuisance tripping"* that the staff will enjoy!

However; see my post under your other thread - maybe they have been provided to meet a spec about "wet locations" - but I would still question the 10 mA setting.

No doubt this reference will muddy the waters for you even further! In other words, when it comes to "wet location(s)" - versus - IPS(s) it seems to be an "either-or" situation (and it sounds like your hospital may have chosen the "wrong" one)!

Meanwhile, are there any line circuit breakers anywhere in evidence (at a panel on the wall, perhaps)?

By the way:- I see you are in Singapore; do you still use the British-style 13-A (polarized) plugs (with fuse) and socket outlets?

* Due to "inrush current" on switch-on, for example.

OK - I've got it now; it seems there are basically two types of RCDs:-

1) Type 1 : nominal tripping current 10 mA AC
2) Type 2 : nominal tripping current 30 mA AC


See here.