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#1
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Metal transformer enclosure purpose?
Clamshell-looking enclosure on small AC power transformers. Magnetic
shielding to prevent interference with nearby wires? |
#2
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Metal transformer enclosure purpose?
On Sat, 02 Mar 2013 20:00:49 -0800, Frank wrote:
Clamshell-looking enclosure on small AC power transformers. Magnetic shielding to prevent interference with nearby wires? Magnetic fields are hard to shield. In a power transformer, it would be more effective to use more iron in the core and more turns in the windings to reduce the flux density. While a steel shell probably provides a limited amount of shielding, it's more likely there to provide mechanical protection. At the same time, it gives a better appearance. -- Jim Mueller To get my real email address, replace wrongname with dadoheadman. Then replace nospam with fastmail. Lastly, replace com with us. |
#3
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Metal transformer enclosure purpose?
On Sun, 4 Mar 2013, Jim Mueller wrote:
On Sat, 02 Mar 2013 20:00:49 -0800, Frank wrote: Clamshell-looking enclosure on small AC power transformers. Magnetic shielding to prevent interference with nearby wires? Magnetic fields are hard to shield. In a power transformer, it would be more effective to use more iron in the core and more turns in the windings to reduce the flux density. While a steel shell probably provides a limited amount of shielding, it's more likely there to provide mechanical protection. At the same time, it gives a better appearance. Maybe protect the windings, too. Definitely, nobody specifies between just a frame transformer and a metal cased one. I'd honestly never given it any thought. Bigger transformers often seem to be more likely to be cased in metal, so structural support may apply. I don'thave it handy, but that one Hammond catalog I got decades ago I think offered the same voltage/amps in open frame and metal enclosed versions, which would add more to "looks" than anything else. I have heard of the leads breaking off open frame transofrmers, right where they come off the winding, which isn't a good thing. Any metal cased transformer, I don't recall that happening, which may mean there is some sort of terminal block inside, rather than just bringing out the wire. Certainly I've seen open frame transformers where the wire from the windings are brought to terminal points, which helps protect the winding wire. it also exposes the line voltage going into that transformer, which in some cases can't be a good thing. Michael |
#4
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Metal transformer enclosure purpose?
On Mar 3, 7:39*pm, Jim Mueller wrote:
On Sat, 02 Mar 2013 20:00:49 -0800, Frank wrote: Clamshell-looking enclosure on small AC power transformers. *Magnetic shielding to prevent interference with nearby wires? Magnetic fields are hard to shield. *In a power transformer, it would be more effective to use more iron in the core and more turns in the windings to reduce the flux density. *While a steel shell probably provides a limited amount of shielding, it's more likely there to provide mechanical protection. *At the same time, it gives a better appearance. Surprised no one's made them gold plated. |
#5
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Metal transformer enclosure purpose?
On Mar 3, 9:49*pm, Michael Black wrote:
On Sun, 4 Mar 2013, Jim Mueller wrote: On Sat, 02 Mar 2013 20:00:49 -0800, Frank wrote: Clamshell-looking enclosure on small AC power transformers. *Magnetic shielding to prevent interference with nearby wires? Magnetic fields are hard to shield. *In a power transformer, it would be more effective to use more iron in the core and more turns in the windings to reduce the flux density. *While a steel shell probably provides a limited amount of shielding, it's more likely there to provide mechanical protection. *At the same time, it gives a better appearance. Maybe protect the windings, too. Definitely, nobody specifies between just a frame transformer and a metal cased one. *I'd honestly never given it any thought. *Bigger transformers often seem to be more likely to be cased in metal, so structural support may apply. *I don'thave it handy, but that one Hammond catalog I got decades ago I think offered the same voltage/amps in open frame and metal enclosed versions, which would add more to "looks" than anything else. I have heard of the leads breaking off open frame transofrmers, right where they come off the winding, which isn't a good thing. *Any metal cased transformer, I don't recall that happening, which may mean there is some sort of terminal block inside, rather than just bringing out the wire. *Certainly I've seen open frame transformers where the wire from the windings are brought to terminal points, which helps protect the winding wire. *it also exposes the line voltage going into that transformer, which in some cases can't be a good thing. * *Michael Or if it's installed in a perforated enclosure. Paper and wire varnish don't protect as well against sharp objects. |
#6
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Metal transformer enclosure purpose?
On Sun, 03 Mar 2013 23:13:17 -0800, Frank wrote:
On Mar 3, 7:39Â*pm, Jim Mueller wrote: On Sat, 02 Mar 2013 20:00:49 -0800, Frank wrote: Clamshell-looking enclosure on small AC power transformers. Â*Magnetic shielding to prevent interference with nearby wires? Magnetic fields are hard to shield. Â*In a power transformer, it would be more effective to use more iron in the core and more turns in the windings to reduce the flux density. Â*While a steel shell probably provides a limited amount of shielding, it's more likely there to provide mechanical protection. Â*At the same time, it gives a better appearance. Surprised no one's made them gold plated. I have seen chrome in imported equipment where everything is chrome plated. I've also seen some with a finish that looks sort of gold colored. Perhaps it is some kind of zinc chromate coating. -- Jim Mueller To get my real email address, replace wrongname with dadoheadman. Then replace nospam with fastmail. Lastly, replace com with us. |
#7
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Metal transformer enclosure purpose?
On Saturday, March 2, 2013 11:00:49 PM UTC-5, Frank wrote:
Clamshell-looking enclosure on small AC power transformers. Magnetic shielding to prevent interference with nearby wires? IMO it's an electrical code requirement or navy military designation every military grade transformer I've see is hermetically sealed 73 de n8zu |
#8
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Metal transformer enclosure purpose?
On Mar 17, 10:56*am, raypsi wrote:
On Saturday, March 2, 2013 11:00:49 PM UTC-5, Frank wrote: Clamshell-looking enclosure on small AC power transformers. *Magnetic shielding to prevent interference with nearby wires? IMO it's an electrical code requirement or navy military designation every military grade transformer I've see is hermetically sealed True of the several WWII / Korea vintage transformers in my junk box. |
#9
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Metal transformer enclosure purpose?
On 18/03/13 04:58, Frank wrote:
On Mar 17, 10:56 am, raypsi wrote: On Saturday, March 2, 2013 11:00:49 PM UTC-5, Frank wrote: Clamshell-looking enclosure on small AC power transformers. Magnetic shielding to prevent interference with nearby wires? IMO it's an electrical code requirement or navy military designation every military grade transformer I've see is hermetically sealed True of the several WWII / Korea vintage transformers in my junk box. =========================== A metal enclosure (apart for mechanical protection) can be avoided by using toroid transformers ,similar to RF toroids ,not requiring a shielding can like cylinder shape inductors with or without a ferrous core ,which need a screening can. Frank GM0CSZ / KN6WH |
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