I fully agree Jacco. The current through your body will never trip a 16 A mains-fuse. Only in case of the phase-wire in an appliance touching the metal case (assuming its connected to safety-earth) the fuse will trip.(pls correct me if i'm wrong).btw Jacco, that separation-transformer made me drool (not a good idea with this kind of weather 😀 )
In the meanwhile, i still see no reason to connect a secondary ground of a ps to safety-earth. If you did this at both pre-amp and power-amp this would cause a big groundloop.
With kind regards,
Klaas
In the meanwhile, i still see no reason to connect a secondary ground of a ps to safety-earth. If you did this at both pre-amp and power-amp this would cause a big groundloop.
With kind regards,
Klaas
Absolutely right... but a simple earth ground doesn't always mean very little. Think about appliances like dishwashers and washing machines where without an earth ground on the frame a failure of an electrical component (like happened to me 2 days ago on dishwasher) could mean electrocution since the frame might go to the high side of the AC! Many simple earth grounds are VERY VERY important!!!!!!!!! Not all homes and buildings in the States are equipped with ground fault breakers but all new build definately is. Ground fault breakers were the last safety device to make their way into the National Electrical Code. Also we have AC outlets that have built in Ground fault breakers and a test button. These make safety upgrades very easy for the average home owner to perform himself. Above all they should always be installed in all bathrooms/kitchen areas or where ever there might be contact with AC and water.
Mark
Klaas,
sometimes they are offered as a batch, like 100 EC bucks for 4.
You do need a softstarter for them(sequential ones at that), even connected to two 16-amps fuses i haven't been able to get them online without a softstarter.
see: marktplaats=> scheidingstrafo , beschermingstrafo , veiligheidstrafo. (the URL doesn't work)
This is how your chest looks like when the sparks pop out and no ground breaker present=>
For defib lovers: left side, right above the home of Mr Cordis.
sometimes they are offered as a batch, like 100 EC bucks for 4.
You do need a softstarter for them(sequential ones at that), even connected to two 16-amps fuses i haven't been able to get them online without a softstarter.
see: marktplaats=> scheidingstrafo , beschermingstrafo , veiligheidstrafo. (the URL doesn't work)
This is how your chest looks like when the sparks pop out and no ground breaker present=>
For defib lovers: left side, right above the home of Mr Cordis.
Attachments
AndrewT said:
Thanks,
I have no source connected, in fact, no wires to the board yet. I also have a freezer in addition to the noisy lighting ballasts local to my testing area. This stuff has tricked me before, and I think it has again!
Thanks Jacco, i'll look at Marktplaats.
Your chest-picture reminds me of the joke "never answer the phone when you're ironing your shirt"
With kind regards,
Klaas
Your chest-picture reminds me of the joke "never answer the phone when you're ironing your shirt"
With kind regards,
Klaas
kvholio said:
At the beach you can always differentiate who's wearing polyester and who's not !
kvholio said:
What if your sec. ground were not tied to chassis, and one of your secondary live wires touched chassis? Wouldn't this either cause a hazard or at the very least other gear to smoke instead of just popping the equip. fuse?
edit: I'm not 100% on this but I think I remember Pass saying to possibly use a thermistor between sec. gnd and chassis gnd to eliminate the potential loop. I still feel better with a direct connect. Safety first IMHO.
Think you've made a good point there Mpmarino. I'm not really worried about my puny +/- 34 V in my ksa, but it makes me wonder about my commercial pre-amp (tubes=high voltage) 
with kind regards,
Klaas
with kind regards,
Klaas
Mpmarino, from looking at your pictures it appears to me you havent connected your signal-ground to your ps-ground. maybe this causes your problem.
With kind regards,
Klaas
With kind regards,
Klaas
I guess I missed that one too. 
Thanks. I'll try to try that tonight.
Boy, I haven't been paying attention the last 3 or 4 thousand posts I guess🙂
Thanks. I'll try to try that tonight.Boy, I haven't been paying attention the last 3 or 4 thousand posts I guess🙂
kvholio said:Think you've made a good point there Mpmarino. I'm not really worried about my puny +/- 34 V in my ksa, but it makes me wonder about my commercial pre-amp (tubes=high voltage)
with kind regards,
Klaas
A puny =/- 34V maybe
but 2mA across the heart will stop it
and these amps make good arc welders.
allan
ps If you get a tingle from your appliances.
something might be wrong.
pps jacco
nylon carpets are still more fun
awpagan said:
Actually, if you do some googling you'll find that the limit is 30mA, the German Reich had the opportunity to do some practical research in that field of expertise 60 years ago.
The 30mA value is where ground breakers are based on, Adolf was good for something.
You should meet my cousin. Give her nylon and she's a walking talking powerstation. Her butt is too big for a Robert Palmer video, though.( 3AM, can't sleep)
jacco vermeulen said:
actually i thought it was 20mA but i'll accept 30mA (speaking figuratively, of course)
still +/- 34V at how many amps.
allan
ps power an electric car?
pps is that where the expression came from
"don't give me static"
According to the Nen1010 (Dutch safety-regulations for electrical installations) 50V AC (50Hz) and 120V DC are considered "safe".
This means 68V DC is not going to zap you (cause severe heartrhythm-problems).I wouldnt try it.
As to my understanding, as long as the circuit carrying the voltage can deliver those 30 mA without the voltage sagging, you are toast.
You could get a very nasty burn when you happen to short charged ps-caps.Discharge properly before tooling around.
Dont disconnect your secondary ps-ground from your safety-earth.SAFETY FIRST
With kind regards,
Klaas
This means 68V DC is not going to zap you (cause severe heartrhythm-problems).I wouldnt try it.
As to my understanding, as long as the circuit carrying the voltage can deliver those 30 mA without the voltage sagging, you are toast.
You could get a very nasty burn when you happen to short charged ps-caps.Discharge properly before tooling around.
Dont disconnect your secondary ps-ground from your safety-earth.SAFETY FIRST
With kind regards,
Klaas
I forgot that Anders went on vacation this week so I wont be hearing anything about the badges untill next. My misstake.
No. a secondary by definition is isolated from the mains.
That is the BIG difference between ordinary transformers and "autotransformers" which have no isolation and must be treated as if "live" even though they might be issuing apparently low voltage.
An isolated secondary DOES NOT NEED a chassis connection. Some designers may choose to make a secondary to chassis connection to meet their performance requirements.
Secondary fuses do offer some advantages but they are usually fitted after the smoothing caps so unfortunately there are some wires that remain with only primary fuse protection.
It is reliance on good primary fuse protection that has moved me to soft start.
Without soft start the primary fuse usually has to have a rating of about three times the maximum operating current of the transformer.
With soft start, the primary fuse can be reduced substantially and I try to achieve a rating of less than 80% of maximum operating current. A potential improvement (reduction) of 4:1.
As an aside, all the socket circuits in my house have individual RCBOs at the distribution board EXCEPT the music system on the lounge circuit. I will NEVER plug a hand tool into my lounge ring so I am not reliant on the extra protection afforded by the RCBO.
Mark,
I don't think electrocution in bathrooms has anything to do with changing the safety earth rules in the US.
We have had three wire systems in the UK longer than I've been alive and folk get electrocuted regularly. Most often due to equipment faults, or during maintenance, or due to stupid operating habits (you've all seen the horror movies where the mains connected radio falls/gets thrown into the bath).
Removing the risk from wet areas needs a completely different solution/mindset.
Kv,
please explain your reasoning.
Andrew, my reasoning had nothing to do with engineering.It occurred to me this morning that ,not knowing his EXACT circuitry and also not knowing his level of expertise, it would be best (and most safe) to "pull the handbrake " and not change ANYTHING envolving safety and wait for a more educated person to step in.
I basically didnt want to "zap" Mpmarino .
i understand your reasoning about connecting ps-ground to safety-earth .i do not use it and i will not use it.
Andrew, from extensively reading this thread , in my opinion , you should be given the honorary title "Mr. grounding". Take this as a compliment.It's meant as such.
With kind regards,
Klaas
I basically didnt want to "zap" Mpmarino .
i understand your reasoning about connecting ps-ground to safety-earth .i do not use it and i will not use it.
Andrew, from extensively reading this thread , in my opinion , you should be given the honorary title "Mr. grounding". Take this as a compliment.It's meant as such.
With kind regards,
Klaas
Thanks, but I don't deserve it.
I simply try to understand what others are saying and interpret the answers. None of it is mine nor original. I am on a learning curve, just like most others are that try to make progress.
If you read again you will note a slight change in emphasis from previous posts. I omitted the reference to keeping the power, signal, safety, and digital grounds completely separate until they reach the Central Star Ground. I am now a little unsure about how important that part of my advice was.
I do know that it worked and allowed maximum flexibility if grounding problems were encountered.
My biggest improvement would be finding a way to be succinct (brevity & clarity), but that might be a target too far.
I simply try to understand what others are saying and interpret the answers. None of it is mine nor original. I am on a learning curve, just like most others are that try to make progress.
If you read again you will note a slight change in emphasis from previous posts. I omitted the reference to keeping the power, signal, safety, and digital grounds completely separate until they reach the Central Star Ground. I am now a little unsure about how important that part of my advice was.
I do know that it worked and allowed maximum flexibility if grounding problems were encountered.
My biggest improvement would be finding a way to be succinct (brevity & clarity), but that might be a target too far.