Good video reminding that there are more than one way to make an isolation transformer... Thus, one should check how the isolation transformer is made and whether it is suitable for particular application without modification.
Ya pretty much none are sold for safety/repair- only noise isolation and they still don't really work for that as sold :) Isolating earth is a pretty bad no-no in most countries
It's so simple yet, so confusing. For me it's the neutral reference to ground. When you touch the neutral and ground, there's continuity. It seems like it just negates the whole thing. Meaning you can get rid of the ground but if the ground and neutral are referenced, the ground is still there.
Your definition of a "tech" isolation transformer is different from most others writing about isolation transformers. The more common definition is that the secondary is floating with respect to ground, so that you cannot get a shock by touching the circuit and earth ground at the same time. This transformer's isolated outputs appear to meet this definition as it came from the factory. On the other hand, most "tech" isolation transformers (with 3-wire outputs) do connect output ground to input ground (e.g. look at any of the Hammond isolation transformers, 171 or 178 series). So this is already a "tech" isolation transformer, by the usual definition. Some people argue that output ground should also be unconnected in an isolation transformer, among them the BBC. BBC document EGN-4 explains why. But the BBC doesn't just say to leave the connected device ungrounded - it recommends connecting any exposed metal on the device to an external ground screw that is supplied on BBC-spec isolation transformers. Operating a 3-wire device with ground unconnected can reduce safety (by allowing the device case to become hot) in some circumstances, while improving it (by reducing the amount of grounded stuff on the bench) in others, so it's not something you always want. So, I always leave the ground pins connected on my isolation transformers. 2-wire hot-chassis devices don't care anyway. If I ever want to disconnect the ground on a 3-wire device, I can use a plug-in 2-wire to 3-wire adapter.
Can you please confirm..that to make this a tech isolation transformer, you essentially disconnected the ground pin from the isolated outlet, (from being connected to the primary ground)..? If this is indeed the case, . Isn't this unsafe to have the ground pin not connected to anything? Doesn't the device under test require this ground for safety? Or This is indeed characteristic of tech isolated transformers..? Thanks for the video..
So I would have expected both secondary transformer wires to go directly to the outlets, but am I right that one goes to the power switch? Why would you switch both primary, and secondary sides... I assume the primary side is switched... right?
What if I use a pure sine wave inverter that's powered by 12V DC, those, by their very nature are isolated from mains earth. The DC would be supplied by a lab bench power supply rated for the current needed to sufficiently power the pure sine wave inverter at full load. Wouldn't this work to isolate my device under test ? I lose some energy from the conversion but it's not being used to power constantly on high powered devices to begin with so the losses should only amount to a few cents a year at best.
The ground/neutral connections could still be coupled, also unless you’re spending an absolute ton of money on a really high-end inverter… The “pure sine wave“ is never a perfect waveform. Which can cause a lot of issues in some devices.
@@hullinstruments The the only thing connected to a wall socket would be the lab power supply. Not worried there A good pure sine wave inverter is probably still loads cheaper than buying a good isolation transformer.
A lot of these isolated transformers not only have the ground plug of the outlet grounded to the chassis but the neutral is bonded to ground also so that needs to be addressed to make these a fully isolated transformer for tech work. Removing just the outlet ground will not protect you because the neutral in the mains service box is earth.bonded, you are still grounded.
The mains neutral connects to the primary side of the input winding. The two wires coming from the secondary have no physical contact with the primary. The only common wire is the earth wire and once that is physically removed from the output you should be ok . One other issue involves the mounting screws on the metal container. If your output sockets are mounted to the metal container then they will be grounded and as most of these sockets have a common output earth in order to ground the mounting bracket. You should physically cut the metal band from the earth connection to the screw hole of the container . This depends on where you live and the type of electrical plug sockets used in that area.
@@conwaynoel3715 Why not just leave the Earth pin of the secondary as they are and just use a 2-pin plug or a plug-in 2-wire to 3-wire adapter.to connect to your DUT? I was told that I could use a RCD plug (GFCI in USA) on the secondary of the I/T if I want to.
What about plugging the scope into the isolation transformer as well. I would think that would eliminate the concern of grounding the scope probes to the chassis of the unit under test.
Not recommended for a few reasons. At this stage you should really know what you are doing and not need that. I hesitated to even publish this video as most people probably just shouldn't be working on 110.
@@MkmeOrg I'm one of those. But I want to learn how to work on 230 because I have many projects using mains. Where can I learn how to do that as safe as possible? Thanks!
More of my budget electronics lab gear here: th-cam.com/play/PLxyM2a_cfnziFGACUATNoAV2UB1EBBT5c.html
Good video reminding that there are more than one way to make an isolation transformer... Thus, one should check how the isolation transformer is made and whether it is suitable for particular application without modification.
Ya pretty much none are sold for safety/repair- only noise isolation and they still don't really work for that as sold :) Isolating earth is a pretty bad no-no in most countries
It's so simple yet, so confusing. For me it's the neutral reference to ground. When you touch the neutral and ground, there's continuity. It seems like it just negates the whole thing. Meaning you can get rid of the ground but if the ground and neutral are referenced, the ground is still there.
Would you also be able to use those adapters that negate the ground pin so it never makes contact with the isolation transformer?
One of the best troubleshooting video on isolation transformers. Good job.
I just gave the guts of that transformer away about 20 mins ago. This would have been a cool project with it. Thanks for sharing.
Your definition of a "tech" isolation transformer is different from most others writing about isolation transformers. The more common definition is that the secondary is floating with respect to ground, so that you cannot get a shock by touching the circuit and earth ground at the same time. This transformer's isolated outputs appear to meet this definition as it came from the factory. On the other hand, most "tech" isolation transformers (with 3-wire outputs) do connect output ground to input ground (e.g. look at any of the Hammond isolation transformers, 171 or 178 series). So this is already a "tech" isolation transformer, by the usual definition.
Some people argue that output ground should also be unconnected in an isolation transformer, among them the BBC. BBC document EGN-4 explains why. But the BBC doesn't just say to leave the connected device ungrounded - it recommends connecting any exposed metal on the device to an external ground screw that is supplied on BBC-spec isolation transformers. Operating a 3-wire device with ground unconnected can reduce safety (by allowing the device case to become hot) in some circumstances, while improving it (by reducing the amount of grounded stuff on the bench) in others, so it's not something you always want.
So, I always leave the ground pins connected on my isolation transformers. 2-wire hot-chassis devices don't care anyway. If I ever want to disconnect the ground on a 3-wire device, I can use a plug-in 2-wire to 3-wire adapter.
I put a switch in to have ground connected or disconnected. And there is enough room to put in a dim bulb outlet.
Can you please confirm..that to make this a tech isolation transformer, you essentially disconnected the ground pin from the isolated outlet, (from being connected to the primary ground)..?
If this is indeed the case, . Isn't this unsafe to have the ground pin not connected to anything? Doesn't the device under test require this ground for safety?
Or
This is indeed characteristic of tech isolated transformers..?
Thanks for the video..
Alas, we may never know.
It is safe as it is isolated.
can you also put a dim bulb setup too
tfw the only isolation in the isolationtransformer is the enamel and tape on the windings
So I would have expected both secondary transformer wires to go directly to the outlets, but am I right that one goes to the power switch? Why would you switch both primary, and secondary sides... I assume the primary side is switched... right?
What if I use a pure sine wave inverter that's powered by 12V DC, those, by their very nature are isolated from mains earth.
The DC would be supplied by a lab bench power supply rated for the current needed to sufficiently power the pure sine wave inverter at full load.
Wouldn't this work to isolate my device under test ?
I lose some energy from the conversion but it's not being used to power constantly on high powered devices to begin with so the losses should only amount to a few cents a year at best.
The ground/neutral connections could still be coupled, also unless you’re spending an absolute ton of money on a really high-end inverter… The “pure sine wave“ is never a perfect waveform. Which can cause a lot of issues in some devices.
@@hullinstruments The the only thing connected to a wall socket would be the lab power supply. Not worried there
A good pure sine wave inverter is probably still loads cheaper than buying a good isolation transformer.
A lot of these isolated transformers not only have the ground plug of the outlet grounded to the chassis but the neutral is bonded to ground also so that needs to be addressed to make these a fully isolated transformer for tech work. Removing just the outlet ground will not protect you because the neutral in the mains service box is earth.bonded, you are still grounded.
The mains neutral connects to the primary side of the input winding. The two wires coming from the secondary have no physical contact with the primary. The only common wire is the earth wire and once that is physically removed from the output you should be ok . One other issue involves the mounting screws on the metal container. If your output sockets are mounted to the metal container then they will be grounded and as most of these sockets have a common output earth in order to ground the mounting bracket. You should physically cut the metal band from the earth connection to the screw hole of the container . This depends on where you live and the type of electrical plug sockets used in that area.
@@conwaynoel3715 Why not just leave the Earth pin of the secondary as they are and just use a 2-pin plug or a plug-in 2-wire to 3-wire adapter.to connect to your DUT?
I was told that I could use a RCD plug (GFCI in USA) on the secondary of the I/T if I want to.
What about plugging the scope into the isolation transformer as well. I would think that would eliminate the concern of grounding the scope probes to the chassis of the unit under test.
Not recommended for a few reasons. At this stage you should really know what you are doing and not need that. I hesitated to even publish this video as most people probably just shouldn't be working on 110.
Sorry not "you" you but "people" you :)
@@MkmeOrg I'm one of those. But I want to learn how to work on 230 because I have many projects using mains. Where can I learn how to do that as safe as possible? Thanks!
The? Never plug more than one thing in an isolation transformer.