It's a safety hazard, the insulation protects the windings from physical damage, and provides the required additional layer of insulation to meet electrical safety requirements.
If you have damaged the wire insulation and then accidentally touched the damaged area you could get a shock or worse. There is also the possibility of a shorted turn due to the attempt at removing the insulating wrap which at best depending on how the transformer is protected could result in blown fuses or tripped breaker or a thermal event in the transformer if the fault current was insufficient to trip the protective device. You should have a breaker or fuse on the transformer primary and not rely on the breaker in your panel for protection.
I cannot tell you that it is safe to use in its current state, so you do so at your own risk.
Either of the tapes you mention.should be fine.
Yeah, the bunnies are very spoiled. We have 3 of them total, 2 are a bonded pair and the other is a singleton, the pair and the singleton have to be kept separate so we have barricades all over the house. Two of the 3 are extremely mobile and have no problem on hardwood and resilient flooring so we have barricades to prevent their meeting under uncontrolled circumstances. Bunny fights are pretty scary to behold.
Thanks kevinkr. I'm confident that the insulation isn't harmed.
I'll grab the tape that you recommend and reseal the wrapping.
(I didn't know rabbits engaged in hostilities but I guess there's no reason why
they should be different than the most of the rest of the animal kingdom.)
I'll grab the tape that you recommend and reseal the wrapping.
(I didn't know rabbits engaged in hostilities but I guess there's no reason why
they should be different than the most of the rest of the animal kingdom.)
Sounds good, just make sure to fuse the primary. I think a 10A MDL type should be a good starting point.
We've had pet bunnies for 18years now and we've still not entirely figured them out. They have distinctly different personalities and our singleton acts more like a cat or dog than a bunny - comes when name called, follows us around, nuzzles us to get attention, and can pretty much get into all of the same mischief our cats do. She particularly likes to jump up on the dinning room table. Their teeth are very sharp, able to sever a USB cable in milli-seconds or take a chomp out of a doily, place mat, my jeans.. LOL
We've had pet bunnies for 18years now and we've still not entirely figured them out. They have distinctly different personalities and our singleton acts more like a cat or dog than a bunny - comes when name called, follows us around, nuzzles us to get attention, and can pretty much get into all of the same mischief our cats do. She particularly likes to jump up on the dinning room table. Their teeth are very sharp, able to sever a USB cable in milli-seconds or take a chomp out of a doily, place mat, my jeans.. LOL
I can't find 10A Bussmann MDL fuses rated above 32V.
Will any 10A slow blow fuse rated above 120V be suitable?
http://www.cooperindustries.com/con...ct-datasheets-a/Bus_Ele_DS_2004_MDL_MDL-V.pdf
Will any 10A slow blow fuse rated above 120V be suitable?
http://www.cooperindustries.com/con...ct-datasheets-a/Bus_Ele_DS_2004_MDL_MDL-V.pdf
Here are some options in 5 x 20mm format: https://www.digikey.com/en/products...VHcjAqDTiANRAgjXiOrx8jDKzcgqLS8slzKnVUYrxWSSA
A slow blow type is acceptable. I would probably use an 8A in that case.
A slow blow type is acceptable. I would probably use an 8A in that case.
Thanks for the tips.
This is how I plan to wire it. (Thought I'd make sure first this time.) 🙂
The lower color diagram is wiring I copied from a different transformer.
The upper B&W diagram is what I propose to use.
Should the self resetting thermal switches be added?
This is how I plan to wire it. (Thought I'd make sure first this time.) 🙂
The lower color diagram is wiring I copied from a different transformer.
The upper B&W diagram is what I propose to use.
Should the self resetting thermal switches be added?
Attachments
You want to wire the connections exactly as shown in the bottom diagram. Don't forget to add the fuse, then switch on the line (not neutral side).
The bottom diagram is NOT for the transformer that I have.
My question is, did I match the function of the bottom diagram with the top
diagram using the wire colors from the transformer I have?
The picture lists the colors.
My question is, did I match the function of the bottom diagram with the top
diagram using the wire colors from the transformer I have?
The picture lists the colors.
I understand that, but the connections in your diagram don't seem to match what is needed. you show three connections where two are called for. The connections and colors you show are all incorrect.
As follows:
Primary:
Line - connect brown and orange together (IEC L > Fuse > Switch > brown/orange)
Neutral - connect yellow and gray together (IEC N > yellow/gray)
Secondary:
"Line 1" Connect black and blue together (this is line on your output outlet)
"Line 2" Connect white and red together (this is neutral on your output outlet)
GRN/WHT connect to your safety GND. (Transformer mounted in grounded metal box)
Do you have an EE friend or electrician nearby who can help you check this out to make sure it is safe?
As follows:
Primary:
Line - connect brown and orange together (IEC L > Fuse > Switch > brown/orange)
Neutral - connect yellow and gray together (IEC N > yellow/gray)
Secondary:
"Line 1" Connect black and blue together (this is line on your output outlet)
"Line 2" Connect white and red together (this is neutral on your output outlet)
GRN/WHT connect to your safety GND. (Transformer mounted in grounded metal box)
Do you have an EE friend or electrician nearby who can help you check this out to make sure it is safe?
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Parts are on the way but I have a new concern. I don't have a link but Kuba Ober had this to say:
(Also refers to static electricity and the shield I damaged.)
"Your output can be floating without connecting neutral to ground, just like you did, but you risk damaging your transformer’s winding insulation with static electricity. You need a “fail-safe” transzorb between neutral and ground, set to 90% of the insulation voltage rating of the transformer. A “fail-safe” transzorb is simply a couple of them connected in series. This is not something theoretical. It’s very easy to damage transformers that way, and is often a source of “unexplained” leakage currents through locations where the winding insulation broke down — usually to the core of the transformer.
You must also note that the benefits you get from floating the output the way you do are mostly imaginary. In other words: people imagine the benefits that aren’t there in reality. Look at any switching power supply that you may connect to such an isolation transformer. There will be capacitors between L and PE (Earth), and between N and PE. Similar capacitors are in EMC filters in many pieces of equipment you might want to isolate with such a transformer. Those capacitors un-isolate your secondary, and make it dangerous to work on. YOU HAVE BEEN FOLLOWING SOME SERIOUSLY BAD ADVICE AND IT CAN KILL YOU. Don’t say I didn’t warn you.
A true floating-output isolated supply has, in fact, isolated ground, but that isolated ground must be connected to the center tap of the secondary winding and nowhere else. If the secondary has no tap, like in your case, you can connect to the secondary’s “neutral”, but that’s sub-optimal. For protection from static electricity you still need transzorbs between the floating PE and “real” PE."
(Also refers to static electricity and the shield I damaged.)
"Your output can be floating without connecting neutral to ground, just like you did, but you risk damaging your transformer’s winding insulation with static electricity. You need a “fail-safe” transzorb between neutral and ground, set to 90% of the insulation voltage rating of the transformer. A “fail-safe” transzorb is simply a couple of them connected in series. This is not something theoretical. It’s very easy to damage transformers that way, and is often a source of “unexplained” leakage currents through locations where the winding insulation broke down — usually to the core of the transformer.
You must also note that the benefits you get from floating the output the way you do are mostly imaginary. In other words: people imagine the benefits that aren’t there in reality. Look at any switching power supply that you may connect to such an isolation transformer. There will be capacitors between L and PE (Earth), and between N and PE. Similar capacitors are in EMC filters in many pieces of equipment you might want to isolate with such a transformer. Those capacitors un-isolate your secondary, and make it dangerous to work on. YOU HAVE BEEN FOLLOWING SOME SERIOUSLY BAD ADVICE AND IT CAN KILL YOU. Don’t say I didn’t warn you.
A true floating-output isolated supply has, in fact, isolated ground, but that isolated ground must be connected to the center tap of the secondary winding and nowhere else. If the secondary has no tap, like in your case, you can connect to the secondary’s “neutral”, but that’s sub-optimal. For protection from static electricity you still need transzorbs between the floating PE and “real” PE."
I have never heard of Kuba Ober, I question the validity of some of his claims, but not the one relating specifically to EMC filters.
Any device connected to the isolation transformer must be effectively connected to a protective earth (PE) ground.
The design of EMC filters (specifically any with capacitors connected between line, neutral and PE) and inter-winding capacitance in the isolation transformer may allow significant leakage currents to flow between an ungrounded chassis and grounded person, interconnects, etc.
There are other potential leakage sources, such as capacitance between the primary windings and core in a power transformer which is usually connected to the device chassis.
These represent a potential shock hazard in specific instances, and knowing enough to recognize when the hazard exists is important.
Medical grade isolation transformers are designed to have very low inter-winding capacitances to minimize leakage currents from primary to secondary but leakage current is never zero, so there is a path present between primary and secondary, and in conjunction with other leakage paths in the connected device could present an unexpected hazard..
Understanding how to apply an isolation transformer so that it provides a potential benefit and does so safely requires a certain level of knowledge which I think you do not yet possess.
Isolation transformers may not be permitted in some jurisdictions per electrical code except in lab, service and medical applications. You need to check your local electrical code.
I have tried to help, but I having a continuing high level of discomfort based on your posts, and obvious inexperience. I am glad you are aware that there may be some potential risks, but I am not sure whether you would recognize them in practice.
Building devices that operate off of AC mains implies some familiarity with potential hazards and how to avoid them.
I would recommend more research and possibly some schooling before you proceed further. (Many tech high schools and maker orgs offer evening electronics classes for adults - might be worth checking out.)
As always proceed at your own risk.
Any device connected to the isolation transformer must be effectively connected to a protective earth (PE) ground.
The design of EMC filters (specifically any with capacitors connected between line, neutral and PE) and inter-winding capacitance in the isolation transformer may allow significant leakage currents to flow between an ungrounded chassis and grounded person, interconnects, etc.
There are other potential leakage sources, such as capacitance between the primary windings and core in a power transformer which is usually connected to the device chassis.
These represent a potential shock hazard in specific instances, and knowing enough to recognize when the hazard exists is important.
Medical grade isolation transformers are designed to have very low inter-winding capacitances to minimize leakage currents from primary to secondary but leakage current is never zero, so there is a path present between primary and secondary, and in conjunction with other leakage paths in the connected device could present an unexpected hazard..
Understanding how to apply an isolation transformer so that it provides a potential benefit and does so safely requires a certain level of knowledge which I think you do not yet possess.
Isolation transformers may not be permitted in some jurisdictions per electrical code except in lab, service and medical applications. You need to check your local electrical code.
I have tried to help, but I having a continuing high level of discomfort based on your posts, and obvious inexperience. I am glad you are aware that there may be some potential risks, but I am not sure whether you would recognize them in practice.
Building devices that operate off of AC mains implies some familiarity with potential hazards and how to avoid them.
I would recommend more research and possibly some schooling before you proceed further. (Many tech high schools and maker orgs offer evening electronics classes for adults - might be worth checking out.)
As always proceed at your own risk.
I understand that you are new on here, and obviously not educated in electrical safety procedures.
With that said, even being guided on here by other members, I'd strongly advise doing some learning about at least the basics before attempting further messing around.
For your own good.
Thank you for your concern. I acknowledge that I'm a novice and hope to be cautious/fearful enough to succeed but will leave that for you to decide.
I'll refrain from plugging the thing in until I've documented the progress here for criticism. (I do feel embarrassed with the schematic misinterpretation on my part. That was just some mental block I developed I guess.)
I'll be using the isolation transformer to work on vintage audio gear. With no external ground on the stuff, it seemed safest. One hand, don't let the juice flow across the chest, etc. (I have put in a new 200 amp service to this 100 year old house of mine last year; no electrician, state inspected and approved.)
In addition to youtube videos, reading through parts of several books at the same time, I'm about 1/4 through this course:
https://www.udemy.com/course/crash-course-electronics-and-pcb-design/
So hopefully, I'll pick up some bits along the way.
I'm ordering parts to recap a couple of integrated amps and a power supply that I'm working on so hope to figure out the transorbs needed and get them at the same time. One thing that I read said that putting a couple in series was a failsafe method?
Again, my thanks for the advice and concern.
I'll refrain from plugging the thing in until I've documented the progress here for criticism. (I do feel embarrassed with the schematic misinterpretation on my part. That was just some mental block I developed I guess.)
I'll be using the isolation transformer to work on vintage audio gear. With no external ground on the stuff, it seemed safest. One hand, don't let the juice flow across the chest, etc. (I have put in a new 200 amp service to this 100 year old house of mine last year; no electrician, state inspected and approved.)
In addition to youtube videos, reading through parts of several books at the same time, I'm about 1/4 through this course:
https://www.udemy.com/course/crash-course-electronics-and-pcb-design/
So hopefully, I'll pick up some bits along the way.
I'm ordering parts to recap a couple of integrated amps and a power supply that I'm working on so hope to figure out the transorbs needed and get them at the same time. One thing that I read said that putting a couple in series was a failsafe method?
Again, my thanks for the advice and concern.
😱 I can't help myself. Please go have a look at the schematic of a manufactured isolation transformer for guidance. I own at least 3 commercial or medical grade isolation transformers, not one of them has a TVS (transorb) between either output leg and PE. One of them was designed specifically for bench use.
https://www.digikey.com/en/articles...n-transformers-and-how-to-select-and-use-them
Just because you read it on the internet (including here) does not mean it is correct. I have never, ever, ever seen an isolation transformer damaged by ESD. A transorb provides a dangerous and unwanted leakage path between a safely isolated secondary winding and ground.
Again at your own risk, you need to wait, slow down, and learn how to do this safely. I recommend you just buy one ready to go.
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You understand that while we are qualified to do this work, we aren't in a position to qualify another person to do it. That is (in my country) a government matter. Nuance can be difficult to impart over a thread. The thing that concerns me is the way you're jumping into the fire first time around. I understand the logic of needing this device for future work, I'd be happier to see you purchasing a completed unit for this.
Very valid point on the reliability of "what you read on the internet" and the primary reason I wanted to ask about transorbs here.
After reading the quote that I linked, I found no others recommending them but they did seem to have pretty neat properties so I asked.
I will now forget about using them. Thank you
Thanks AllenB for your thoughts. I understand your concern and agree that I'm not qualified. (And frankly, perhaps I should have purchased a complete
isolation transformer.) Since I already have the unit now, I'll document the build for critique.
Here in the USA, there are strict electrical codes that MUST be adhered to.
Because liability issues can arise from improper safety measures.
For a long time I've always kept that in mind through my decades of servicing customer's equipment at the shop.
I specialized in doing "vintage restorations" and got a flood of work from customers.
In fact, with "vintage" products made before current codes were introduced, I've made "upgrades" to wiring, and added fuses where needed to insure that I won't have to deal with a liability issue and lawsuits.
Even the simple 5-tube AM radios got a polarized plug/cord and some re-wiring of the chassis.
Because liability issues can arise from improper safety measures.
For a long time I've always kept that in mind through my decades of servicing customer's equipment at the shop.
I specialized in doing "vintage restorations" and got a flood of work from customers.
In fact, with "vintage" products made before current codes were introduced, I've made "upgrades" to wiring, and added fuses where needed to insure that I won't have to deal with a liability issue and lawsuits.
Even the simple 5-tube AM radios got a polarized plug/cord and some re-wiring of the chassis.
I'd like to hear about those "upgrades" wiseoldtech! I've read a lot of restoration/recap threads for vintage equipment and have yet to see even a ground added. (my interest is old solid state but find tube discussions interesting too.)
The "recapping" craze started on the internet is way overblown and in many cases not necessary for many "vintage" products.
Back around 2002-2005 is when the whole craze started due to a bad batch of electrolytics got into consumer equipment.
Since then, it's drawn hoardes of obsessed, paranoid, and nervous nutbags into that rabbit hole of nonsense.
Yes, on occasion, caps do go bad, but in my experience at the shop, servicing thousands of audio and video products over the decades, I never experienced anything that would result in justifying a nutty "cap craze".
Whenever I see comments that force a justification of "recapping", I just shake my head and think: "You fools, you nutbag wannabe techs, you don't know what I know!"
As for electrical upgrades, it depends on the specific unit in question - there is no single specific way to conduct modifications.