Will an old tube light choke work for very small loads as a filter?
My molding machine has a 200V secondary transformer, primary taps for 200/220/240V, 750VA, very good isolation.
The new PLC has EMI filters before the SMPS, but I insisted the isolation transformer from the old PLC be left in place, the old PLC was erratic due to ageing issues.
My molding machine has a 200V secondary transformer, primary taps for 200/220/240V, 750VA, very good isolation.
The new PLC has EMI filters before the SMPS, but I insisted the isolation transformer from the old PLC be left in place, the old PLC was erratic due to ageing issues.
If anyone in the EU wants to try this device out: I decided to sell it as I don't need 1 kVA. Please send me PM if you want it.
Just noticed this thread:
With US voltages often approaching 125V125V (the NEC spec is now 125V) using a 115V transformer on 125V might make the transformer very unhappy
With US voltages often approaching 125V125V (the NEC spec is now 125V) using a 115V transformer on 125V might make the transformer very unhappy
Some time ago i built an isolation transformer box (3kVa) and this was a very noticable improvent for my tube gear.
Last month i built a common mode filter with custom coils from 2.1 mm2 OCC wire, nano crystaline cores (15mH) and some safety caps. This filter was a way bigger improvement than the isolation transformer. Easy and fun to build.
Last month i built a common mode filter with custom coils from 2.1 mm2 OCC wire, nano crystaline cores (15mH) and some safety caps. This filter was a way bigger improvement than the isolation transformer. Easy and fun to build.
Attachments
So the best combo seems to be both a mains filter and an isolation transformer. The medical transformers are often better than the standard types. Is yours silent? I have tried many but most types above 500VA are humming too much.
Indeed easy and fun to build but not for everyone I noticed. The challenge to make it safe and esthetically pleasing adds to that. When things are concerning mains voltage and PE many turn a blind eye 😉
Indeed easy and fun to build but not for everyone I noticed. The challenge to make it safe and esthetically pleasing adds to that. When things are concerning mains voltage and PE many turn a blind eye 😉
Last edited:
Yes, and this is because the the surface finish can provide enough insulation, so that two panels, bolted together, could still be electrically isolated. The anodized finish of aluminum is an insulator, and for steel it's the paint. "Toothed" washers that "bite" through the finish are used where the PE wires connect to a panel.
On bigger machines, a PE wire is used to connect a metal hinged door to the metal frame, even if the hinges are metal. Hinges can get oiled and oil is and insulator. It's all about safety.
True, this 'audio grade' transformer also has a slight 50Hz hum. I eliminated the problem by attaching the transformer cabinet to the wall with rubber dampening plugs specifically made to dampen vibrations.
The small Shurter filters in the cabinet are only for powering my network switch and Roon server.
Haven't tried any "audio grade" versions (and probably never will) but used normal European quality industrial ones and medical ones sometimes even both of the same brand. The latter are extremely low leakage and that apparently shows. The humming can be between different types of the same brand tested at the same time so it is a case of coincidence and some luck. Not all need a DC component to hum, some do it very nicely without any DC. The ones that have epoxy in the middle seem to be less noisy.
I recently was showed a 2 kVA pro device and it hummed so loud that it interfered with the goal in audio 🙂
I recently was showed a 2 kVA pro device and it hummed so loud that it interfered with the goal in audio 🙂
Last edited:
Menno van der Veen at Plitron Transformers, thinks so.
http://www.idc-online.com/technical...MEASURING_ACOUSTIC_NOISE_EMITTED_BY_POWER.pdf
and a lot of the audiophile DC blockers are actually dealing with over-voltage problems.
It depends a lot on the transformer design, and a lot of audiophiles have bugs in their minds.
For industrial design, one of the important parameters is called "factor of safety".
So most equipment is built to take all sorts of sudden loads with little disturbance.
These people think they are very intelligent, we do not share this opinion.
This joker has not specified the steel and thickness used in the transformers, which is how the magnetic fields transfer the electricity.
That is stupid, to put it mildly.
I read till page 7 of 19, seems to be more of a presentation to a conference, the later pages would be references and bibliography.
I know many people in the transformer industry, core losses in power transformers are a big issue, these people were testing what are toys in comparison.
You can look up eddy current and hysteresis losses in CRGO (Cold Rolled Grain Oriented) steel, same grade, different thicknesses.
That is the steel to be used for transformer laminations.
Change in thickness from 0.3 to 0.4 changes the transformer performance.
Change in grade is an even bigger effect, and so is the price difference between grades.
Flatness of the sheets is an issue, wrinkled sheets which have been banged back into shape are not allowed in high voltage transformers.
We must follow best practice in isolation transformers, so the manufacturing and assembly must be of the highest standard also.
A good design is of no use if the build is shoddy.
I pity his customers.
A transformer in the field will have to see a lot more than lab conditions, and must be over rated in the design stage itself.
And think of Japanese audio set transformers, they do not hum when they get 60 or 50 Hz (many were dual voltage dual frequency sets).
This clown is saying transformers will hum if driven into saturation at wrong frequency, for which it was not designed.
He has compared 50 and 60 Hz, on toy transformers.
Simple, design it so it is not saturated.
These mentally challenged people are probably also teachers. Pity.
Footnote: The company has been sold to Noratel for 4 million dollars, and the name changed. The old name is gone.
4 million is not a very big amount today, about 2 houses in Toronto these days.
For industrial design, one of the important parameters is called "factor of safety".
So most equipment is built to take all sorts of sudden loads with little disturbance.
These people think they are very intelligent, we do not share this opinion.
This joker has not specified the steel and thickness used in the transformers, which is how the magnetic fields transfer the electricity.
That is stupid, to put it mildly.
I read till page 7 of 19, seems to be more of a presentation to a conference, the later pages would be references and bibliography.
I know many people in the transformer industry, core losses in power transformers are a big issue, these people were testing what are toys in comparison.
You can look up eddy current and hysteresis losses in CRGO (Cold Rolled Grain Oriented) steel, same grade, different thicknesses.
That is the steel to be used for transformer laminations.
Change in thickness from 0.3 to 0.4 changes the transformer performance.
Change in grade is an even bigger effect, and so is the price difference between grades.
Flatness of the sheets is an issue, wrinkled sheets which have been banged back into shape are not allowed in high voltage transformers.
We must follow best practice in isolation transformers, so the manufacturing and assembly must be of the highest standard also.
A good design is of no use if the build is shoddy.
I pity his customers.
A transformer in the field will have to see a lot more than lab conditions, and must be over rated in the design stage itself.
And think of Japanese audio set transformers, they do not hum when they get 60 or 50 Hz (many were dual voltage dual frequency sets).
This clown is saying transformers will hum if driven into saturation at wrong frequency, for which it was not designed.
He has compared 50 and 60 Hz, on toy transformers.
Simple, design it so it is not saturated.
These mentally challenged people are probably also teachers. Pity.
Footnote: The company has been sold to Noratel for 4 million dollars, and the name changed. The old name is gone.
4 million is not a very big amount today, about 2 houses in Toronto these days.
Last edited:
My state, Gujarat alone annually buys 150,000 power distribution transformers, suppliers have to guarantee performance for 3 to 5 years, free transport and repairs if failure occurs.
Backed by iron clad bank guarantees.
Most are 25 to 200 kVA 11 kV, and some are in the 220 kV 20MVA class, in between 66 kV, and 132 kV are also needed.
Very thorough type testing certificates are needed to even qualify to bid for the order.
These toy maker guys are poseurs.
And their words are being taken as gospel. Even bigger pity.
Backed by iron clad bank guarantees.
Most are 25 to 200 kVA 11 kV, and some are in the 220 kV 20MVA class, in between 66 kV, and 132 kV are also needed.
Very thorough type testing certificates are needed to even qualify to bid for the order.
These toy maker guys are poseurs.
And their words are being taken as gospel. Even bigger pity.
Th theory behind an isolation transformer is that line noise is of too short a duration to be properly induced in the secondary, and it is lost in the magnetic fields,and also the duration changes, the excess energy is dissipated.
A line filter before the transformer also helps, I think more than one on the secondary side.
The person above has not described the transformers, both his own make and the other tested ones, one is simply listed as E-I transformer of unknown make.
See if he has given temperature rise, load percentage, duration of test, and tested at steady state or immediately after starting.
For a consistent result, the transformer should be on load, at design ambient temperature.
To get to that temperature takes some time.
The testing equipment was in a box about the same size as a large speaker.
All in all, shoddy work.
A line filter before the transformer also helps, I think more than one on the secondary side.
The person above has not described the transformers, both his own make and the other tested ones, one is simply listed as E-I transformer of unknown make.
See if he has given temperature rise, load percentage, duration of test, and tested at steady state or immediately after starting.
For a consistent result, the transformer should be on load, at design ambient temperature.
To get to that temperature takes some time.
The testing equipment was in a box about the same size as a large speaker.
All in all, shoddy work.