Laptop trollys tripping power.

[maniac]

Not sure which catagory to put this in, so I picked this one.

We have four trollys of 15 laptops each in areas of our school. The problems we are haivng is they appear to be tripping the electric circuits in the school on a regular basis. They are all in different parts of the building, and every one of them has tripped a circuit at least once, but we've two trollys in particular that trip circuits pretty much on a daily basis. The circuits vary from a 16A supr to a full 32A ring main, on, it makes no difference what sort of circuit they are plugged into, it trips them all.

Has anyone else experienced problems with laptop chargers tripping the circuits in their schools, or have we got some faulty power adapters in there somewhere??

For your information, every one of the power adpaters was recently PAT tested, as were the cabinets themselves, and they all passed with no faults.

Many Thanks,

Mike.

[bishopsgarthstockton]

We had a problem with our main server triping the power, we had a dedicated ring installed just for the server room. Have'nt had a trip ever since.

I would have the council electrician pop in and discuss a solution. Not alot you can do.

[Andrew_C]

Is it an RCD tripping, or an MCB? If it is an RCD what is likely to be happening is that each device has filter capacitors between live and earth. This leaks a small current which is allowed, but when you have lots of devices doing it leads to problems.

Best bet is to talk to a sparks and have a less sensitive device fitted.

If it is the MCB tripping it indicates an overload, or a fault. Again, you need to talk to an electrician.

[maniac]

it's an MCB.

I've just done some further reading up, and discoverd we have the wrong sort of MCB protecting the curcuits. We have a type 'B' MCB, which is a fast reacting fairly sensitive trip. The recommended type for ICT equipment is a slower reacting type D which should stop it tripping on the intial rush of current from the transformers when they are plugged in.

Might be useful to other people if they are having problems with MCB tripping to check the type of MCB they have protecting the circuit.

Mike.

[plexer]

When plugging them in for use if you have a printer and/or access point on it that's all that needs to be powered so you could turn off the chargers.

Bretford do an intelligent power option for their trolleys which prevents the inrush of all the chargers at one go tripping it.

Ben

[maniac]

We've several other laptop trollys with proper power management, but the ones in question are cheap trollys that just have the laptop PSUs tied in the back of them. The trolleys are only plugged in for charging, there's no printer or access point with them.

We've solved this one now anyway, we've just looked over the pannel for the building that's causing us most of the problems, and all the other RCD's for the ICT related circuits in the panel are 'C' rated, except 3 of them, one of which happens to be the circuit that's causing us problems. Was very pleased to discover this, as this has been puzzling us for ages!

Mike.