Hi,

I hope that I have placed this thread in the correct section?,

I work for a UK company and we Supply various types of Tools and machinery, one of my favourite parts of the job is "troubleshooting" as and when we

have a escalated PCB issue, mainly with PWM or speed control drives, Its my role to investigate the possible reasons for the failure, and then suggest improvements to our supplier in Taiwan & China.

Very often they instantly say that "we never have these PCB failures in Europe & America" !!!!!!!!!!!!!!!!!

*Often its the same design of PCBs used around the world, although made for the correct voltage, Some boards are also interchangeable with UK & America and have a jumper wire or switch that you change depending on the input voltage.

I often would take there comments "with a pinch of salt" , although a recent example has shown that we in the UK do seem to have many more failures then the rest of world !!!!!!!!!!!!!!!!

Am I missing something ? Is this possible ? would be great to hear any feedback on this !!!

Thanks Aspiespot.

 

What is the nature of the failure?

 

Very difficult to offer much based on the lack of information provided.

I don't know how one example is going to somehow show that you have many more failures than the rest of the world.

Assuming that you do, then something is different about the UK compared to the rest of the world (as seen by these boards). It could be lots of things. The power being supplied might be different, possibly have more transient spikes. The environmental conditions might be different, such as temperature and humidity. The loads might be different, such as different kinds of motors being driven. The installations might be different, such as different grounding and shielding. The handling procedures might be different, such as not taking the same anti-static precautions when installing the boards. The applications might be different, such as using the boards in a manner that places more stress on them.

 

A failure description and a basic diagnosis result would help tremendously.
Otherwise I would say that the Chinese are getting back at the UK for having implemented on Hong Kong driving on the wrong side of the road.

 

Knowing what the fault was would help . . .
Is it due to the supply voltage? Because the British 230V supply is a higher voltage than the European 230V supply voltage.
The British supply used to be 240V and the European supply used to be 220V. Back in 1989 they were "unified" to 230V by EU Harmonised Document HD472:S1, but in fact nothing changed. The British supply is 230V +10%-6% and the European supply is 230V +6%-10%.
So, if your transformers and motors are not designed for 253V they will run warn. Filament lamps will have a third of the life, but will be 30% brighter, and the rectified supply will be too much for a 350V electrolytic.
The 230V +10%-6% supply also applies to Australia.

 

Ian0 could be on the right track in that the actual mains voltage in the UK is 240V, although being within the permissible range of a nominal 230V supply.

 

What about the mains frequency??? That might have an effect.
My suggestion depends on what is done when there is a repor5ted failure. Is the product repaired, or replaced, or is the customer simply sold a replacement??If the product is repaired or replaced then exactly what has failed can be discovered simply by demanding a trade-in for it to be replaced under warranty. Then evaluate the failed products as they are returned. That would be the simplest scheme.

 

Not the mains frequency - usually spot on 50Hz. It is accurate enough that clocks based on synchronous motors keep time. (More accurate than some of the 32.768kHz crystal ones). Though a transformer designed for 60Hz would be in trouble.
Supply impedance is 0.243+0.23j Ω for a domestic supply, which seems reasonably normal.

 

Hmmmm…
The TS appears to have lost interest in this thread.

 

The mains frequency within the UK and Europe is very stable; there was a European Union proposal to have all new domestic fridges/freezers fitted with a device that switched off the appliance once the mains frequency dropped below 49.5Hz. The idea being that the national grid could automatically cut supply demand when peak demand approached overload limits.

The proposal was never implemented, with the additional cost of the device being estimated at around £40.

The UK mains frequency is not as stable as Ian0 implies, the reason that mains synchronous clocks in the UK keep accurate time is that the number mains cycles is controlled/counted over the period of a week – meaning that over a long period the clocks will keep very good time.

 

What is the nature of the failure?

Hi, Normally a typical failure for us would be like a dead short normally caused by a diode or capacitor, these are normally easy to troubleshoot and feedback to the factory. The latest issue is with a drum sanding machine and the PCB controls the 90vdc motor. I have checked out all the component's on the switching side and they all seem OK. I'm certain the issue is on the lower voltage side (5v),assume the area which controls the gate on the MOFSET. Sadly trying to find an issue on the low voltage side is way beyond skill level!!! The failures are ALL within the first few hours of use, the PCB just stops working, no bangs ,no burning smells etc

 

Knowing what the fault was would help . . .
Is it due to the supply voltage? Because the British 230V supply is a higher voltage than the European 230V supply voltage.
The British supply used to be 240V and the European supply used to be 220V. Back in 1989 they were "unified" to 230V by EU Harmonised Document HD472:S1, but in fact nothing changed. The British supply is 230V +10%-6% and the European supply is 230V +6%-10%.
So, if your transformers and motors are not designed for 253V they will run warn. Filament lamps will have a third of the life, but will be 30% brighter, and the rectified supply will be too much for a 350V electrolytic.
The 230V +10%-6% supply also applies to Australia.

Wow I had no idea the UK voltage could be 253V!!!!!

 

Hmmmm…
The TS appears to have lost interest in this thread.

OOOooppps sorry for my late replies ,Defo not lost interest

 

Thanks very much for your replies, Interesting that the upper UK voltage could be 253V,and the hertz sound stable ,although static has been mentioned, The PCB is fitted on a woodworking drum sander, I'm wondering if it could be static issue and especially if its connected to dust extraction that has no grounding ?MMMMmm thanks for all your help,Aspiespot

 

Wow I had no idea the UK voltage could be 253V!!!!!

But surely you would have found that out when you were checking if it complied with EN60335 (or whatever standard applies to your product)

 

Here a good one We have 9 new air compressors the have smart switches in them there rated at 100 to 240 volt for limit inputs.
so 5 of these quit $500 a pop each smart switch. Well we couldn't keep this up so I take readings on the voltage that is powering these 265 the transformer for these comes off the 480 supply voltage they had used transformers for 460 volt supply that kills the smart switches in about 4 months of use.

I replaced all 9 with name brand transformers rated at 480 too 240 problems solved

 

there was a European Union proposal to have all new domestic fridges/freezers fitted with a device that switched off the appliance once the mains frequency dropped below 49.5Hz.

what a wonderful idea... risk the food go bad and sending people to hospital. and not because of some failure but because mains frequency changed 0.5Hz. as if performance of fridges or air conditioners in Europe is not already nearly useless crap. every time i visit, frown at what they serve as "cold drink". and don't get me started on what they call an "air conditioned" room.

 

0.5Hz is a huge shift in a large synchronous generator network. Our site energy monitor would go nuts and would likely start up the local transfer to generation protocol as a precaution.

 

agreed and from mains one should of course expect better. but that is not the point.

the evil idiots out there, propping themselves to positions to power are trying way too hard to control each and every aspect of everyone else's life down to a smallest thing. so who the F has the gall to even mention such invasive measures?
so it is not enough that one is ditching incandescent bulbs and get LEDs, nooooo, the largest LED lamp you can own will be 10W, and room can only have up to two. and when you walk into a hotel room, with all lights on, the strongest source of light is your own phone flashlight - the place looks like a dim cave, it is hard to even read the book. oh and you want to run to a store for 10min so you you are hoping to have the phone or laptop charge a bit in that time? nope. because the same card that lock the room is the one used to enable power to every outlet in that space that you PAY FOR. WTF!? someone need to smack the Greta over her ugly head.

if i pay for something, it is up to ME to decode what that is to be be used for. and i find it inexcusable that appliance would shut itself down for such stupid reason. this would limit how, when and where something so essential could be used. a simple example - what about being able to use own generator, wind turbine, hamster wheel attached to a dynamo? the frequency of many such devices is not nearly as tight, they heavily depend on load.

so flick of just one centrally controlled switch (by some would be Mr Burns or whatever tyrant) would be enough to destroy food , poison and decimate entire population because nobody would be able to preserve it even when they do own one of many alternative sources of power. so submit to some overlord and be part of the grid or no food or drinks or comfort?

 

agreed and from mains one should of course expect better. but that is not the point.

the evil idiots out there, propping themselves to positions to power are trying way too hard to control each and every aspect of everyone else's life down to a smallest thing. so who the F has the gall to even mention such invasive measures?
so it is not enough that one is ditching incandescent bulbs and get LEDs, nooooo, the largest LED lamp you can own will be 10W, and room can only have up to two. and when you walk into a hotel room, with all lights on, the strongest source of light is your own phone flashlight - the place looks like a dim cave, it is hard to even read the book. oh and you want to run to a store for 10min so you you are hoping to have the phone or laptop charge a bit in that time? nope. because the same card that lock the room is the one used to enable power to every outlet in that space that you PAY FOR. WTF!? someone need to smack the Greta over her ugly head.

if i pay for something, it is up to ME to decode what that is to be be used for. and i find it inexcusable that appliance would shut itself down for such stupid reason. this would limit how, when and where something so essential could be used. a simple example - what about being able to use own generator, wind turbine, hamster wheel attached to a dynamo? the frequency of many such devices is not nearly as tight, they heavily depend on load.

so flick of just one centrally controlled switch (by some would be Mr Burns or whatever tyrant) would be enough to destroy food , poison and decimate entire population because nobody would be able to preserve it even when they do own one of many alternative sources of power. so submit to some overlord and be part of the grid or no food or drinks or comfort?

If you noticed, I gave your comment a like.

The evil of the Nanny state. That's why I'm building my own power grid.