The Chinese device will just be a single giant MOV. MOVs are quite capable of handling currents of up to about 50-60 kA if large enough. MOVs are needed for a phase to earth or phase to neutral SPD. GDTs don't self reset in the presence of voltage - MOVs automatically return to high resistance state once voltage falls below the threshold. GDTs remain in a low resistance state until the current flow stops. If placed in a PN or PE position, once triggered, they would form a continuing short-circuit until the device was destroyed or overcurrent protection tripped. GDTs are acceptable for use on a neutral-earth position where continuing current would not be expected. MOVs and GDTs are OK for "type 2" and "type 3" SPDs - which are intended for indirect lightning or switching surges. However, "type 1" SPDs intended for direct lightning suppression need to use spark gaps, as the energies expected are far too high to be practically managed with MOVs. Spark gaps also have the problem of shorting out the mains supply until the end of the AC line cycle, which adds to the energy they must dissipate, and also results in voltage dips which can upset sensitive equipment. There is a conspiracy theory circulating from a manufacturer of MOV devices that the spark gap SPD manufacturers managed to twist the arm of the standards committee, and get them to set the minimum specifications so high that MOVs and GDTs were out of the question, allowing spark gaps to corner the type 1 SPD market. TVS diodes are another SPD option, they are like MOVs but trigger faster and harder. They are hugely more expensive than MOVs, and available in much smaller current ratings. However, the higher performance makes them suitable for use on very sensitive high-end electronics, and the low capacitance means that they don't cause much degradation to digital signals, so can be used on high speed data cables.
YES it was interesting - I was wondering how they worked - The components must only be penny's - If a MCB can be made and sold for £5 they MUST be able to make these cheaper than £75 !!!!!Thank for the video good work
I've watched this video multiple times since it was released, and only now i realized that "BG" is a credible name. Both modules are cheap on AliExpress and they all look the same. BG just put its logo on the device and gets £70 in profits.
I bought lots of BG chrome face plates onces. Never again will I buy BG. They are terrible over priced rubbish. The dimmer switches had nothing but problems and the TV aerial socket had poor connections leading to signal break up. The twin socks have hard to push rocker switches and plugs have to be forced in.
The price must be a result of R&D and QA costs compared to production low volumes. But I am sure they do not make them for charity and there is a good amount for profit included as well.
AAAAAAaaaaa what no hammer of truth I wanted to see some plastic flying!!! It's amazing how once the government says you have to have something the price of that something goes through the roof!!
Low temp aloy releases spring loaded tab. When the MOV's have died they overheat and trigger it. Flag changes colour and button on the back pops out. That little button on the back pushes a microswitch to remote signal that protection has failed. The cheapo chineese ones only have MOV's. The propper high grade units normaly have TVS, Gas discharge and MOV. Does the paperwork with the £75 unit mention insurance cover at all ? If not you would be better of with a decent UPS to protect any expensive kit. I have a 3.2 KVA APC unit and that claims it can take a 15 million Joule's. You get a £1M insurance policy / garentee with it to. P.S. I used to work for openreach and they removed the gas discharge surge arrestors from there NTE's or master sockets years ago.
so actually you can reuse the device after its popped? just push those elements back and re-sold them and they are ready to do the job again, I suppose!
Um, no, that's actually very dangerous. It doesn't trip after every surge that the device dissipates. But every surge will degrade the protection devices (especially the metal oxide varistor) a little bit, to the point where it will start leaking more and more current during normal (non-surge) operation. The low temperature solder connection is there to disconnect it once the leakage current gets to high. Reconnecting it (especially using different solder with a higher melting point!) means you just created a time-delay fire starter (and no, the circuit breaker won't help with that, a leakage current well below its tripping point is enough to catch things on fire; the MCB is there for catastrophic failures, for example after a direkt lightning strike has blown the innards to smithereens).
@@richardneilson No, it won't because the heated contact would be heated for longer time and therefore the solder would have been melted completely and not bridging anything.
