The MOV and the fuse are the two components in the red circle. They have likely gone bad (open fuse and MOV overheated). The 4 diodes needs to be checked and it is a good idea to replace them anyway - they may fail later, as Jean-Paul wrote. This is the easy and cheap quick fix. Other parts may have gone bad, but then replacing the power supply board is usually a better choice.
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The FET in those kind of PSUs are pretty tough as are the diodes.
The MOV will have taken the power to blow the fuse. If the PSU was rated for 110/120 volts it may just have a lower MOV and capacitor in it and otherwise be the same as a 220/240 volt unit.
Most things survive with no more than a blown fuse and MOV if wrongly connected to 220/240 volts while set to 110/120 volts.
Cheap PSUs are often rated for 100 to 250 volts and have no MOV. They have a short life and fail with almost everything burned or cracked.
The MOV will have taken the power to blow the fuse. If the PSU was rated for 110/120 volts it may just have a lower MOV and capacitor in it and otherwise be the same as a 220/240 volt unit.
Most things survive with no more than a blown fuse and MOV if wrongly connected to 220/240 volts while set to 110/120 volts.
Cheap PSUs are often rated for 100 to 250 volts and have no MOV. They have a short life and fail with almost everything burned or cracked.
NO!
Last time it happened to me, a 117V mixer/amplifier and a 117V coffee-pot split the 234V between them. The pot is designed to suck MUCH more current than the mixer. I think it went to 50V on the pot and 180+V on the mixer. Sounded really good! For a few minutes. Then FWOOOM!!! and a mini-mushroom cloud to the ceiling.
You're right.
I was thinking more the neutral bond at the pole, the neutral is bonded to earth at the panel and in that case, circuit neutral current would use earth as return. I guess if the neutral from the transformer isn't connected to earth, it wouldn't work anyway though.
I was thinking more the neutral bond at the pole, the neutral is bonded to earth at the panel and in that case, circuit neutral current would use earth as return. I guess if the neutral from the transformer isn't connected to earth, it wouldn't work anyway though.
The neutral on the pole pig is supposed to be bonded to earth. Usually they use a piece of #8 copper, and the ground rod at the pole isn’t driven in all that far. Don’t count on it to make your neutral - too much ground resistance to do any good there.
Around here, they don't seem to use ground rods but this neighbourhood is served by 27.6kV delta, and the padd transformers are in vaults underground so I can't see grounding.
The neutral is connected to ground in the panel of first entry here (and not any subpanels), with a #4 to #8 (depending on the place/power) clamped to the water supply pipe.
If the customer owns the vault or whatever, there are rules that go beyond code depending on where you are, too. Here's the "cpnstruction" guidelines from Toronto Hydro...
https://www.torontohydro.com/docume...6-0a9c-e762-b4e0-4d69a1a6d718?t=1604053989956
The neutral is connected to ground in the panel of first entry here (and not any subpanels), with a #4 to #8 (depending on the place/power) clamped to the water supply pipe.
If the customer owns the vault or whatever, there are rules that go beyond code depending on where you are, too. Here's the "cpnstruction" guidelines from Toronto Hydro...
https://www.torontohydro.com/docume...6-0a9c-e762-b4e0-4d69a1a6d718?t=1604053989956
My ground impedance is over 40 Ohms. (Five rods in 2 feet of dry sand on bedrock.) That coffee maker wanted to flow 10 Amps. What is the voltage drop?
There are very few cases where dirt can carry ANY useful current on 120/240V systems. (It does play a part in the 20KV system on my street and my neighbor's mile-long drive.)
In the current U.S. National Electrical Code the neutral is referred to as the “Grounded Conductor.” The other grounded conductor not intended to carry power is the “Safety Ground.”
They should be connected to each other only at the point of entrance first power panel. If there are sub-panels they are kept isolated.
The use of the ground to carry current was adopted to save wire, as the U.S. has very long wire runs.
Elsewhere the common wire or “Neutral” is not grounded. This is an advantage with 230 or higher voltage lines as it reduces instances of electrocution.
In this poor souls problem case the common wire looks like it has poor connections at multiple locations. As he lives in a “Flat” and the AC mains are 400 volts that should hint the U.S. code and standards do not apply!
I would splurge and buy three cheap analog AC voltmeters (Typical https://www.amazon.com/Gardner-Bender-GMT-318-Multimeter-Function/dp/B00291X79O/ref=mp_s_a_1_13?crid=1G5B16R4RMH11&keywords=vom&qid=1648120748&sprefix=vom,aps,119&sr=8-13)
and monitor all the phases of the power lines. Then when reporting to the power authority having jurisdiction a report can be made of actual voltage variations, when they occurred, how severe they were and how long they lasted.
I suspect he is budget limited and may wish to either borrow meters or eBay the new ones after use. I would not suggest a digital meter as they require batteries.
Of course the other options would be to increase his fire insurance coverage or move to a new flat!
One more item everyone should have is a smoke detector in the bedroom. In this case I would be sure it is battery power only.
They should be connected to each other only at the point of entrance first power panel. If there are sub-panels they are kept isolated.
The use of the ground to carry current was adopted to save wire, as the U.S. has very long wire runs.
Elsewhere the common wire or “Neutral” is not grounded. This is an advantage with 230 or higher voltage lines as it reduces instances of electrocution.
In this poor souls problem case the common wire looks like it has poor connections at multiple locations. As he lives in a “Flat” and the AC mains are 400 volts that should hint the U.S. code and standards do not apply!
I would splurge and buy three cheap analog AC voltmeters (Typical https://www.amazon.com/Gardner-Bender-GMT-318-Multimeter-Function/dp/B00291X79O/ref=mp_s_a_1_13?crid=1G5B16R4RMH11&keywords=vom&qid=1648120748&sprefix=vom,aps,119&sr=8-13)
and monitor all the phases of the power lines. Then when reporting to the power authority having jurisdiction a report can be made of actual voltage variations, when they occurred, how severe they were and how long they lasted.
I suspect he is budget limited and may wish to either borrow meters or eBay the new ones after use. I would not suggest a digital meter as they require batteries.
Of course the other options would be to increase his fire insurance coverage or move to a new flat!
One more item everyone should have is a smoke detector in the bedroom. In this case I would be sure it is battery power only.
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Simon, thanks to you too!
Since I (and my poor soul 😉) am in switzerland, some of your recommendations don’t seem to apply. Furthermore, I am not allowed to touch anything electrical installation as I‘m not an electrician. It is all done by certified professionals (the gaffes and glitches too!). Moving isn’t an option neither, this place is too good!
Since I (and my poor soul 😉) am in switzerland, some of your recommendations don’t seem to apply. Furthermore, I am not allowed to touch anything electrical installation as I‘m not an electrician. It is all done by certified professionals (the gaffes and glitches too!). Moving isn’t an option neither, this place is too good!
That is simply not true. There are various systems in Europe like TT, TN, TN-C, TN-C-S etc. etc. All are reasonably well thought out and PE is for safety. Most systems are there to keep PE from being a current carrying conductor in normal situations while being conservative with copper usage. Best price/quality ratio as usual, not lowest cost as elsewhere. Thank the Spaghetti Monster that US standards don't apply in Europe.
Regardless of systems... installations sometimes don't age too well and incidents will always happen and our task is to minimize the number of incidents.
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It's referred to as the "designated conductor." No ground fault is supposed to go through the designated conductor, and no return current is supposed to go through the ground.
I've certainly seen otherwise. In old houses and buildings I've seen only hot wires run; the return current goes through the conduit! This is so wrong and so dangerous. It was never allowed by code. If one piece of conduit loosens up, then you have live conduit. Plus you're guaranteed to have flickering lights etc.
Elsewhere perhaps wasn't clear enough. Not everywhere outside the U.S. but some places do not ground the local power. ( I think still catching up.) Having a floating AC power with a safety ground to the metal surfaces of an enclosure does not trip a fuse or breaker, but does provide protection to a user. I have been on two locations where improper (U.S. NEC) grounding has caused a fatality.
In Switzerland they have a common 5 pin outlet. It has 3 phases, common and protective as far as I know. Never had to work there.
As to voltage in the U.S. you will often find small power transformers rated for 110 volt primaries and others for 120 volts. The standard line voltage is now 125 volts or so. It is scheduled to rise slowly to 135 volts. Some locations used to actually run 100 volts at the start of electrification. So the small transformers often touch saturation allowing a more constant peak voltage output but with more waveform distortion.
It should be noted the U.S. National Electrical Code is NOT a standard! It is usually adopted by the local government. One issue is that some have adopted a specific year's code and not the the latest version. Most places have figured out to change the legislation to replace the year with the phrase "current" or some such.
In my shop we get three phase "Y" however the same pole transformer also feeds residences and they get single phase "110." It is actually 127 volts as measured here. So my 208 Volt Y service is actually 220 VAC. An interesting compromise. The 120 is high and the 240 is low for the residences, but both within allowable standards. However my three phase loads are all rated to take 230 volt delta in addition to 208 Y on the same terminals. Now why is it you are skeptical of U.S. standards? 😉
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I wonder how much of THAT is due to the larger and larger fraction of the grid power being generated “locally” through solar, etc. From your power system theory - if you want to inject rather than absorb power, the Thevenin equivalent of the “generator” must be a higher open circuit voltage than the energized system you’re connecting to. What’s coming off your grid tie inverter has got to be at least slightly higher that the 127/254 volts coming off the transformer on the pole (that was lower just 10 years ago). So you‘ve got to increase the maximum allowed in order to keep it in spec.
Could also be part of a plan to obsolete older equipment. Old tube amps with 110 volt transformers buzz like hell when you connect them to 127. Some stuff will run hot and eventually just die. In favor of replacements that have PFC switching supplies that run on anything from 90 to 280 volts without jumper settings (And meet energy star requirements).
Grounded vs grounding. I was taught to call the grounding conductor the designated conductor. I think they taught it that way because grounded vs grounding can be confusing. As my late brother would say "same thing."
It is so common for electrician students to be confused over this concept, but is imperative for safety reasons to get it right before you monkey in that box. It is important to understand that the neutral/grounding conductor/designated conductor is not fused. If wired properly it will not be overloaded and it will be protected by the line breaker. If not, it can easily be overloaded and it will have no protection.
Whatever you call it, I know how to wire up a service box. These concepts may seem simple to you and me but believe me I've seen some very wrong wiring inside the service box.
It is so common for electrician students to be confused over this concept, but is imperative for safety reasons to get it right before you monkey in that box. It is important to understand that the neutral/grounding conductor/designated conductor is not fused. If wired properly it will not be overloaded and it will be protected by the line breaker. If not, it can easily be overloaded and it will have no protection.
Whatever you call it, I know how to wire up a service box. These concepts may seem simple to you and me but believe me I've seen some very wrong wiring inside the service box.
A friend of us, in Zürich, had exactly the same problem - but I do not know if it is already solved. I will ask him.