S
Stu jaxon
Guest
hi group, does anyone know if i can use this= 750 Watt Voltage Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation transformer, it does have output of 110v, ? thanks,
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N
N_Cook
Guest
On 22/11/2017 18:50, Stu jaxon wrote:
Does your ohmeter say there is a connection across both sides? ie an
autotransformer.
hi group, does anyone know if i can use this= 750 Watt Voltage Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation transformer, it does have output of 110v, ? thanks,
Does your ohmeter say there is a connection across both sides? ie an
autotransformer.
P
pfjw@aol.com
Guest
On Wednesday, November 22, 2017 at 1:50:46 PM UTC-5, Stu jaxon wrote:
> hi group, does anyone know if i can use this= 750 Watt Voltage Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation transformer, it does have output of 110v, ? thanks,
Most voltage-converter transformers are auto-transformers and do not provide isolation. As Mr. Cook suggests, see if you get continuity from the primary to the secondary.
http://www.electronics-tutorials.ws/transformer/trans28.gif This is an auto-transformer.
Peter Wieck
Melrose Park, PA
> hi group, does anyone know if i can use this= 750 Watt Voltage Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation transformer, it does have output of 110v, ? thanks,
Most voltage-converter transformers are auto-transformers and do not provide isolation. As Mr. Cook suggests, see if you get continuity from the primary to the secondary.
http://www.electronics-tutorials.ws/transformer/trans28.gif This is an auto-transformer.
Peter Wieck
Melrose Park, PA
J
J.B. Wood
Guest
On 11/22/2017 01:50 PM, Stu jaxon wrote:
Hello, and do you have a particular make and model number of device in
mind? An marketed as an AC isolation transformers usually doesn't
provide voltage conversion with input (primary) to output (secondary)
energy transfer solely via magnetic coupling. There are also adjustable
autotransformers (e.g. the venerable Variac brand) that, for example,
takes 120 VAC at input and can provides 0-130 VAC output. The primary
and secondaries of these devices aren't conductively isolated (as an
ohmmeter test will confirm). There are also devices which combine both
isolation and adjustable autotransformer function in one enclosure. Or
you can simply take, say, a 120 VAC-to-120 VAC isolation transformer and
follow it with an adjustable autotransformer, keeping in mind the
maximum AC current/power ratings of the devices. Sincerely,
--
J. B. Wood e-mail: arl_123234@hotmail.com
hi group, does anyone know if i can use this= 750 Watt Voltage Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation transformer, it does have output of 110v, ? thanks,
Hello, and do you have a particular make and model number of device in
mind? An marketed as an AC isolation transformers usually doesn't
provide voltage conversion with input (primary) to output (secondary)
energy transfer solely via magnetic coupling. There are also adjustable
autotransformers (e.g. the venerable Variac brand) that, for example,
takes 120 VAC at input and can provides 0-130 VAC output. The primary
and secondaries of these devices aren't conductively isolated (as an
ohmmeter test will confirm). There are also devices which combine both
isolation and adjustable autotransformer function in one enclosure. Or
you can simply take, say, a 120 VAC-to-120 VAC isolation transformer and
follow it with an adjustable autotransformer, keeping in mind the
maximum AC current/power ratings of the devices. Sincerely,
--
J. B. Wood e-mail: arl_123234@hotmail.com
S
Stu jaxon
Guest
On Wednesday, November 22, 2017 at 2:39:09 PM UTC-5, J.B. Wood wrote:
here's the model Norstar ST-750.. it's on ebay for half price used. so more or less this just a surge protector.?
On 11/22/2017 01:50 PM, Stu jaxon wrote:
hi group, does anyone know if i can use this= 750 Watt Voltage Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation transformer, it does have output of 110v, ? thanks,
Hello, and do you have a particular make and model number of device in
mind? An marketed as an AC isolation transformers usually doesn't
provide voltage conversion with input (primary) to output (secondary)
energy transfer solely via magnetic coupling. There are also adjustable
autotransformers (e.g. the venerable Variac brand) that, for example,
takes 120 VAC at input and can provides 0-130 VAC output. The primary
and secondaries of these devices aren't conductively isolated (as an
ohmmeter test will confirm). There are also devices which combine both
isolation and adjustable autotransformer function in one enclosure. Or
you can simply take, say, a 120 VAC-to-120 VAC isolation transformer and
follow it with an adjustable autotransformer, keeping in mind the
maximum AC current/power ratings of the devices. Sincerely,
--
J. B. Wood e-mail: arl_123234@hotmail.com
here's the model Norstar ST-750.. it's on ebay for half price used. so more or less this just a surge protector.?
T
Trevor Wilson
Guest
On 23/11/2017 7:16 AM, Stu jaxon wrote:
**No. It's a step-down transformer, or autoformer. No way of knowing,
unless you can contact the manufacturer, or measure it yourself. I doubt
that it is an isolation transformer.
Which begs the question: Why do you need an isolation transformer?
--
Trevor Wilson
www.rageaudio.com.au
On Wednesday, November 22, 2017 at 2:39:09 PM UTC-5, J.B. Wood wrote:
On 11/22/2017 01:50 PM, Stu jaxon wrote:
hi group, does anyone know if i can use this= 750 Watt Voltage Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation transformer, it does have output of 110v, ? thanks,
Hello, and do you have a particular make and model number of device in
mind? An marketed as an AC isolation transformers usually doesn't
provide voltage conversion with input (primary) to output (secondary)
energy transfer solely via magnetic coupling. There are also adjustable
autotransformers (e.g. the venerable Variac brand) that, for example,
takes 120 VAC at input and can provides 0-130 VAC output. The primary
and secondaries of these devices aren't conductively isolated (as an
ohmmeter test will confirm). There are also devices which combine both
isolation and adjustable autotransformer function in one enclosure. Or
you can simply take, say, a 120 VAC-to-120 VAC isolation transformer and
follow it with an adjustable autotransformer, keeping in mind the
maximum AC current/power ratings of the devices. Sincerely,
--
J. B. Wood e-mail: arl_123234@hotmail.com
here's the model Norstar ST-750.. it's on ebay for half price used. so more or less this just a surge protector.?
**No. It's a step-down transformer, or autoformer. No way of knowing,
unless you can contact the manufacturer, or measure it yourself. I doubt
that it is an isolation transformer.
Which begs the question: Why do you need an isolation transformer?
--
Trevor Wilson
www.rageaudio.com.au
S
Stu jaxon
Guest
On Wednesday, November 22, 2017 at 3:41:45 PM UTC-5, Trevor Wilson wrote:
to protect my equipment, i picked up a new hobby.
On 23/11/2017 7:16 AM, Stu jaxon wrote:
On Wednesday, November 22, 2017 at 2:39:09 PM UTC-5, J.B. Wood wrote:
On 11/22/2017 01:50 PM, Stu jaxon wrote:
hi group, does anyone know if i can use this= 750 Watt Voltage Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation transformer, it does have output of 110v, ? thanks,
Hello, and do you have a particular make and model number of device in
mind? An marketed as an AC isolation transformers usually doesn't
provide voltage conversion with input (primary) to output (secondary)
energy transfer solely via magnetic coupling. There are also adjustable
autotransformers (e.g. the venerable Variac brand) that, for example,
takes 120 VAC at input and can provides 0-130 VAC output. The primary
and secondaries of these devices aren't conductively isolated (as an
ohmmeter test will confirm). There are also devices which combine both
isolation and adjustable autotransformer function in one enclosure. Or
you can simply take, say, a 120 VAC-to-120 VAC isolation transformer and
follow it with an adjustable autotransformer, keeping in mind the
maximum AC current/power ratings of the devices. Sincerely,
--
J. B. Wood e-mail: arl_123234@hotmail.com
here's the model Norstar ST-750.. it's on ebay for half price used. so more or less this just a surge protector.?
**No. It's a step-down transformer, or autoformer. No way of knowing,
unless you can contact the manufacturer, or measure it yourself. I doubt
that it is an isolation transformer.
Which begs the question: Why do you need an isolation transformer?
--
Trevor Wilson
www.rageaudio.com.au
to protect my equipment, i picked up a new hobby.
T
Trevor Wilson
Guest
On 23/11/2017 7:46 AM, Stu jaxon wrote:
**An isolation transformer won't protect your equipment. An isolation
transformer is used to assist in protecting the operator (though that is
far from guaranteed).
Why do you imagine that an isolation transformer will protect your
equipment?
What sort of equipment?
What do you imagine the transformer will protect your equipment from?
--
Trevor Wilson
www.rageaudio.com.au
On Wednesday, November 22, 2017 at 3:41:45 PM UTC-5, Trevor Wilson wrote:
On 23/11/2017 7:16 AM, Stu jaxon wrote:
On Wednesday, November 22, 2017 at 2:39:09 PM UTC-5, J.B. Wood wrote:
On 11/22/2017 01:50 PM, Stu jaxon wrote:
hi group, does anyone know if i can use this= 750 Watt Voltage Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation transformer, it does have output of 110v, ? thanks,
Hello, and do you have a particular make and model number of device in
mind? An marketed as an AC isolation transformers usually doesn't
provide voltage conversion with input (primary) to output (secondary)
energy transfer solely via magnetic coupling. There are also adjustable
autotransformers (e.g. the venerable Variac brand) that, for example,
takes 120 VAC at input and can provides 0-130 VAC output. The primary
and secondaries of these devices aren't conductively isolated (as an
ohmmeter test will confirm). There are also devices which combine both
isolation and adjustable autotransformer function in one enclosure. Or
you can simply take, say, a 120 VAC-to-120 VAC isolation transformer and
follow it with an adjustable autotransformer, keeping in mind the
maximum AC current/power ratings of the devices. Sincerely,
--
J. B. Wood e-mail: arl_123234@hotmail.com
here's the model Norstar ST-750.. it's on ebay for half price used. so more or less this just a surge protector.?
**No. It's a step-down transformer, or autoformer. No way of knowing,
unless you can contact the manufacturer, or measure it yourself. I doubt
that it is an isolation transformer.
Which begs the question: Why do you need an isolation transformer?
--
Trevor Wilson
www.rageaudio.com.au
to protect my equipment, i picked up a new hobby.
**An isolation transformer won't protect your equipment. An isolation
transformer is used to assist in protecting the operator (though that is
far from guaranteed).
Why do you imagine that an isolation transformer will protect your
equipment?
What sort of equipment?
What do you imagine the transformer will protect your equipment from?
--
Trevor Wilson
www.rageaudio.com.au
Guest
On November 23, 2017 7:46 AM, Stu jaxon wrote:
From what? And when you say 'surge protector', could you also have 'surge arrestor' (for much un-predictably higher un-controlled voltage input) in mind, as well?
To start with, your hobby device power processing should connect to an un-insulated copper or aluminum wire that should be in properly grounded and secured contact with your facility's (cold) water main.
Additionally, use specifically GFCI-advertized outlets when you think there is danger to people or property. It says that in the recent NEC- book rules, doesn't it?
On Wednesday, November 22, 2017 at 3:41:45 PM UTC-5, Trevor Wilson wrote:
On 23/11/2017 7:16 AM, Stu jaxon wrote:
On Wednesday, November 22, 2017 at 2:39:09 PM UTC-5, J.B. Wood wrote:
On 11/22/2017 01:50 PM, Stu jaxon wrote:
hi group, does anyone know if i can use this= 750 Watt Voltage Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation transformer, it does have output of 110v, ? thanks,
Hello, and do you have a particular make and model number of device in
mind? An marketed as an AC isolation transformers usually doesn't
provide voltage conversion with input (primary) to output (secondary)
energy transfer solely via magnetic coupling. There are also adjustable
autotransformers (e.g. the venerable Variac brand) that, for example,
takes 120 VAC at input and can provides 0-130 VAC output. The primary
and secondaries of these devices aren't conductively isolated (as an
ohmmeter test will confirm). There are also devices which combine both
isolation and adjustable autotransformer function in one enclosure. Or
you can simply take, say, a 120 VAC-to-120 VAC isolation transformer and
follow it with an adjustable autotransformer, keeping in mind the
maximum AC current/power ratings of the devices. Sincerely,
--
J. B. Wood e-mail: arl_1...@hotmail.com
here's the model Norstar ST-750.. it's on ebay for half price used. so more or less this just a surge protector.?
**No. It's a step-down transformer, or autoformer. No way of knowing,
unless you can contact the manufacturer, or measure it yourself. I doubt
that it is an isolation transformer.
Which begs the question: Why do you need an isolation transformer?
to protect my equipment, i picked up a new hobby.
From what? And when you say 'surge protector', could you also have 'surge arrestor' (for much un-predictably higher un-controlled voltage input) in mind, as well?
To start with, your hobby device power processing should connect to an un-insulated copper or aluminum wire that should be in properly grounded and secured contact with your facility's (cold) water main.
Additionally, use specifically GFCI-advertized outlets when you think there is danger to people or property. It says that in the recent NEC- book rules, doesn't it?
Guest
On Wednesday, 22 November 2017 20:46:18 UTC, Stu jaxon wrote:
Your comments indicate that you most likely have several misunderstandings. It's your choice but would probably help you to say a lot more about what you're doing.
NT
On Wednesday, November 22, 2017 at 3:41:45 PM UTC-5, Trevor Wilson wrote:
On 23/11/2017 7:16 AM, Stu jaxon wrote:
On Wednesday, November 22, 2017 at 2:39:09 PM UTC-5, J.B. Wood wrote:
On 11/22/2017 01:50 PM, Stu jaxon wrote:
hi group, does anyone know if i can use this= 750 Watt Voltage Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation transformer, it does have output of 110v, ? thanks,
Hello, and do you have a particular make and model number of device in
mind? An marketed as an AC isolation transformers usually doesn't
provide voltage conversion with input (primary) to output (secondary)
energy transfer solely via magnetic coupling. There are also adjustable
autotransformers (e.g. the venerable Variac brand) that, for example,
takes 120 VAC at input and can provides 0-130 VAC output. The primary
and secondaries of these devices aren't conductively isolated (as an
ohmmeter test will confirm). There are also devices which combine both
isolation and adjustable autotransformer function in one enclosure. Or
you can simply take, say, a 120 VAC-to-120 VAC isolation transformer and
follow it with an adjustable autotransformer, keeping in mind the
maximum AC current/power ratings of the devices. Sincerely,
--
J. B. Wood e-mail: arl_123234@hotmail.com
here's the model Norstar ST-750.. it's on ebay for half price used. so more or less this just a surge protector.?
**No. It's a step-down transformer, or autoformer. No way of knowing,
unless you can contact the manufacturer, or measure it yourself. I doubt
that it is an isolation transformer.
Which begs the question: Why do you need an isolation transformer?
to protect my equipment, i picked up a new hobby.
Your comments indicate that you most likely have several misunderstandings. It's your choice but would probably help you to say a lot more about what you're doing.
NT
J
J.B. Wood
Guest
On 11/22/2017 03:16 PM, Stu jaxon wrote:
That unit appears to be intended for those situations where, say a 120
VAC appliance sold in the U.S. is to be used in another country like the
UK on 240 VAC (also assuming the U.S. appliance can cope with 50 Hz vs
60 Hz). Vice-versa for using a UK-marketed appliance in the U.S. Most
likely it's a single winding transformer with a tap(s), which makes it
an autotransformer (no input-to-output isolation). But it could also
have separate primary and secondary coils. No way to tell from a
picture or not having a schematic. Sincerely,
--
J. B. Wood e-mail: arl_123234@hotmail.com
here's the model Norstar ST-750.. it's on ebay for half price used. so more or less this just a surge protector.?
That unit appears to be intended for those situations where, say a 120
VAC appliance sold in the U.S. is to be used in another country like the
UK on 240 VAC (also assuming the U.S. appliance can cope with 50 Hz vs
60 Hz). Vice-versa for using a UK-marketed appliance in the U.S. Most
likely it's a single winding transformer with a tap(s), which makes it
an autotransformer (no input-to-output isolation). But it could also
have separate primary and secondary coils. No way to tell from a
picture or not having a schematic. Sincerely,
--
J. B. Wood e-mail: arl_123234@hotmail.com
P
pfjw@aol.com
Guest
Some basics:
a) Isolation transformers are designed to protect users under some conditions, and *certain* types of equipment under *VERY* limited conditions. Those latter applications are primarily under hospital and research conditions where an isolated ground is not enough. Generally, RF-shielded rooms use isolation transformers in their power-supplies, for example. But, no equipment protects against deliberate stupidity or carelessness. If one inserts oneself into the circuit, one will be stung.
b) Voltage adjustment transformers tend to be as inexpensive as possible per-watt. A true isolation transformer would have very nearly twice as much conductor in it as a simple auto-transformer. Not t mention more core material as well - I am careful not to use 'copper' or 'iron', as very cheap devices will use neither.
c) Any unnecessary equipment adds a degree of unnecessary complexity - and with it an opportunity for error. I have a 110/220 step-up/down transformer purchased in Saudi Arabia with no markings at all. It came with a Euro/US adaptor that could plug into either side. So, I engraved "High Side" and "Low Side" on. Imagine me going the 'wrong way' in actual use. Not so bad going from 110 to 55 volts. But 220 - 440 V, not so good either.
If you need to step up/down, check the equipment. A surprising amount of vintage audio equipment has multi-tap primary transformers that might require only a simple change in wiring, and a surprising amount of modern consumer electronics have smart supplies that do it all automatically. Otherwise, a brand-name surge protector (with a downline equipment warranty) will be your best option to protect your equipment.
Peter Wieck
Melrose Park, PA
a) Isolation transformers are designed to protect users under some conditions, and *certain* types of equipment under *VERY* limited conditions. Those latter applications are primarily under hospital and research conditions where an isolated ground is not enough. Generally, RF-shielded rooms use isolation transformers in their power-supplies, for example. But, no equipment protects against deliberate stupidity or carelessness. If one inserts oneself into the circuit, one will be stung.
b) Voltage adjustment transformers tend to be as inexpensive as possible per-watt. A true isolation transformer would have very nearly twice as much conductor in it as a simple auto-transformer. Not t mention more core material as well - I am careful not to use 'copper' or 'iron', as very cheap devices will use neither.
c) Any unnecessary equipment adds a degree of unnecessary complexity - and with it an opportunity for error. I have a 110/220 step-up/down transformer purchased in Saudi Arabia with no markings at all. It came with a Euro/US adaptor that could plug into either side. So, I engraved "High Side" and "Low Side" on. Imagine me going the 'wrong way' in actual use. Not so bad going from 110 to 55 volts. But 220 - 440 V, not so good either.
If you need to step up/down, check the equipment. A surprising amount of vintage audio equipment has multi-tap primary transformers that might require only a simple change in wiring, and a surprising amount of modern consumer electronics have smart supplies that do it all automatically. Otherwise, a brand-name surge protector (with a downline equipment warranty) will be your best option to protect your equipment.
Peter Wieck
Melrose Park, PA
G
gregz
Guest
Stu jaxon <stankowalski02@gmail.com> wrote:
Commercial isolation transformers get rid of common mode noise, and since
one leg of output is tied to ground, forms a new local neutral. This
prevents noise differentials between ground and output. There is always
voltage sag, so a120 vol output is at full load. More perhaps too much with
small load. Could be 10- 15% over 120 volts. This is not a test transformer
with isolated output from ground referenced mains. Some have voltage
regulation too.
Greg
On Wednesday, November 22, 2017 at 3:41:45 PM UTC-5, Trevor Wilson wrote:
On 23/11/2017 7:16 AM, Stu jaxon wrote:
On Wednesday, November 22, 2017 at 2:39:09 PM UTC-5, J.B. Wood wrote:
On 11/22/2017 01:50 PM, Stu jaxon wrote:
hi group, does anyone know if i can use this= 750 Watt Voltage
Converter Transformer Heavy Duty Step Up/Down 750W 110-220V as an isolation
transformer, it does have output of 110v, ? thanks,
Hello, and do you have a particular make and model number of device in
mind? An marketed as an AC isolation transformers usually doesn't
provide voltage conversion with input (primary) to output (secondary)
energy transfer solely via magnetic coupling. There are also adjustable
autotransformers (e.g. the venerable Variac brand) that, for example,
takes 120 VAC at input and can provides 0-130 VAC output. The primary
and secondaries of these devices aren't conductively isolated (as an
ohmmeter test will confirm). There are also devices which combine both
isolation and adjustable autotransformer function in one enclosure. Or
you can simply take, say, a 120 VAC-to-120 VAC isolation transformer and
follow it with an adjustable autotransformer, keeping in mind the
maximum AC current/power ratings of the devices. Sincerely,
--
J. B. Wood e-mail: arl_123234@hotmail.com
here's the model Norstar ST-750.. it's on ebay for half price used. so
more or less this just a surge protector.?
**No. It's a step-down transformer, or autoformer. No way of knowing,
unless you can contact the manufacturer, or measure it yourself. I doubt
that it is an isolation transformer.
Which begs the question: Why do you need an isolation transformer?
--
Trevor Wilson
www.rageaudio.com.au
to protect my equipment, i picked up a new hobby.
Commercial isolation transformers get rid of common mode noise, and since
one leg of output is tied to ground, forms a new local neutral. This
prevents noise differentials between ground and output. There is always
voltage sag, so a120 vol output is at full load. More perhaps too much with
small load. Could be 10- 15% over 120 volts. This is not a test transformer
with isolated output from ground referenced mains. Some have voltage
regulation too.
Greg
W
whit3rd
Guest
On Tuesday, November 28, 2017 at 12:48:01 AM UTC-8, GS wrote:
That's only true of SOME isolation transformers; the ones used for
bench safety when working on live equipment do NOT make the
neutral-ground connection.
Commercial isolation transformers get rid of common mode noise, and since
one leg of output is tied to ground, forms a new local neutral.
That's only true of SOME isolation transformers; the ones used for
bench safety when working on live equipment do NOT make the
neutral-ground connection.
Guest
On Tuesday, 28 November 2017 23:08:59 UTC, whit3rd wrote:
quite. And building site transformers earth the centre tap.
Re noise, there's the capacitance...
NT
On Tuesday, November 28, 2017 at 12:48:01 AM UTC-8, GS wrote:
Commercial isolation transformers get rid of common mode noise, and since
one leg of output is tied to ground, forms a new local neutral.
That's only true of SOME isolation transformers; the ones used for
bench safety when working on live equipment do NOT make the
neutral-ground connection.
quite. And building site transformers earth the centre tap.
Re noise, there's the capacitance...
NT
G
gregz
Guest
whit3rd <whit3rd@gmail.com> wrote:
All commercial isolation transformers must inform to code. All Tripplite
isolators are grounded. It worries me some think it's all the same. Easy
enough to examine or measure. Still can be a problem on equipment needing a
ground configuration for the circuitry.
Greg
On Tuesday, November 28, 2017 at 12:48:01 AM UTC-8, GS wrote:
Commercial isolation transformers get rid of common mode noise, and since
one leg of output is tied to ground, forms a new local neutral.
That's only true of SOME isolation transformers; the ones used for
bench safety when working on live equipment do NOT make the
neutral-ground connection.
All commercial isolation transformers must inform to code. All Tripplite
isolators are grounded. It worries me some think it's all the same. Easy
enough to examine or measure. Still can be a problem on equipment needing a
ground configuration for the circuitry.
Greg
W
whit3rd
Guest
On Wednesday, November 29, 2017 at 12:22:46 AM UTC-8, GS wrote:
Commercial isolation transformers are leakage-tested, but the ground-neutral
connection is not always present.
Tripplite also makes smart power strips that won't work if plugged into
an isolation transformer that doesn't strap ground-to-neutral. So, they
work with isolated (hospitals, sometimes) power only if you add a Tripplite isolator.
details are here, in the reviews section:
<https://www.tripplite.com/for-patient-care-vicinity-ul-60601-1-medical-grade-ps-4-15a-hospital-grade-outlets-safety-covers-15-ft-cord~PS415HGULTRA/>
whit3rd <whit3rd@gmail.com> wrote:
On Tuesday, November 28, 2017 at 12:48:01 AM UTC-8, GS wrote:
Commercial isolation transformers get rid of common mode noise, and since
one leg of output is tied to ground, forms a new local neutral.
That's only true of SOME isolation transformers; the ones used for
bench safety when working on live equipment do NOT make the
neutral-ground connection.
All commercial isolation transformers must inform to code. All Tripplite
isolators are grounded.
Commercial isolation transformers are leakage-tested, but the ground-neutral
connection is not always present.
Tripplite also makes smart power strips that won't work if plugged into
an isolation transformer that doesn't strap ground-to-neutral. So, they
work with isolated (hospitals, sometimes) power only if you add a Tripplite isolator.
details are here, in the reviews section:
<https://www.tripplite.com/for-patient-care-vicinity-ul-60601-1-medical-grade-ps-4-15a-hospital-grade-outlets-safety-covers-15-ft-cord~PS415HGULTRA/>
M
Michael A Terrell
Guest
pfjw@aol.com wrote:
That transformer would saturate and either blow a fuse, or overheat
if you fed 220 into a 110 winding, unless it is way over designed. It
would be a 220 to 440 transformer being used at a lower voltage if it
could handle 220 on the 110 winding.
c) Any unnecessary equipment adds a degree of unnecessary complexity - and with it an opportunity for error. I have a 110/220 step-up/down transformer purchased in Saudi Arabia with no markings at all. It came with a Euro/US adaptor that could plug into either side. So, I engraved "High Side" and "Low Side" on. Imagine me going the 'wrong way' in actual use. Not so bad going from 110 to 55 volts. But 220 - 440 V, not so good either.
That transformer would saturate and either blow a fuse, or overheat
if you fed 220 into a 110 winding, unless it is way over designed. It
would be a 220 to 440 transformer being used at a lower voltage if it
could handle 220 on the 110 winding.
Guest
On Wed, 22 Nov 2017 14:39:04 -0500, "J.B. Wood" <arl_123234@hotmail.com>
wrote:
I reaad on some website where someone took two 120 to 240 volt
transformers, connected both 240 windings together and ended up with 120
on the secondary, completely isolated from the AC line. This makes
sense, for someone who has two such transformers on hand. But would not
make sense to buy two transformers.
wrote:
Hello, and do you have a particular make and model number of device in
mind? An marketed as an AC isolation transformers usually doesn't
provide voltage conversion with input (primary) to output (secondary)
energy transfer solely via magnetic coupling. There are also adjustable
autotransformers (e.g. the venerable Variac brand) that, for example,
takes 120 VAC at input and can provides 0-130 VAC output. The primary
and secondaries of these devices aren't conductively isolated (as an
ohmmeter test will confirm). There are also devices which combine both
isolation and adjustable autotransformer function in one enclosure. Or
you can simply take, say, a 120 VAC-to-120 VAC isolation transformer and
follow it with an adjustable autotransformer, keeping in mind the
maximum AC current/power ratings of the devices. Sincerely,
I reaad on some website where someone took two 120 to 240 volt
transformers, connected both 240 windings together and ended up with 120
on the secondary, completely isolated from the AC line. This makes
sense, for someone who has two such transformers on hand. But would not
make sense to buy two transformers.
M
Michael A Terrell
Guest
tabbypurr@gmail.com wrote:
IOW, they convert the European 240volt system to the American
120V/240V system.
On Tuesday, 28 November 2017 23:08:59 UTC, whit3rd wrote:
On Tuesday, November 28, 2017 at 12:48:01 AM UTC-8, GS wrote:
Commercial isolation transformers get rid of common mode noise, and
since one leg of output is tied to ground, forms a new local
neutral.
That's only true of SOME isolation transformers; the ones used for
bench safety when working on live equipment do NOT make the
neutral-ground connection.
Quite. And building site transformers earth the centre tap.
IOW, they convert the European 240volt system to the American
120V/240V system.