Timeline for Why my Toroid Isolation Transformer has 112.3v to soil
Current License: CC BY-SA 4.0
16 events
| when toggle format | what | by | license | comment | |
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| Dec 8, 2018 at 6:50 | comment | added | Jtl | Please tell me Ale. I plan to get the same 1182 toroidal series but 1000va (my existing is only 300va). This is to be used on 2 refrigerators that don't have any grounding (our house is so old and just 2 wire). Now can the 1182 series isolates against soil level ground (in case hot wire touches refrigerator chassis). Is it really isolated from primary soil level ground.. or does the poor capacitive coupling which doesn't eliminate common mode still able to protect from ground like what isolation transformers are supposed to do? Please let me know before I buy the 1000va 1182 toroids. Thanks. | |
| Dec 7, 2018 at 14:57 | comment | added | Jtl | I'm looking for a brand of Toroid isolation transformer with electrostatic shielding. There may be one brand which has this. Unless there is just none in the whole world? Is it not possible to put electrostatic shielding in any Toroid isolation transformer? | |
| Dec 7, 2018 at 8:27 | comment | added | Ale..chenski | @Jtl, if you have special requirements as low magnetic interference, then encapsulate the entire transformer into a thick custom-made magnetic enclosure made of transformer steel or Nu Metal. No one will do it for you. | |
| Dec 7, 2018 at 8:14 | comment | added | Jtl | test projects involve magnetic field sensors, so need least interference. The toroid has 20 times less magnetic field than the shell type. So 100 uA can't shock me? I know shocking would require 8mA. So the toroid I bought is really a semi isolation transformer? | |
| Dec 7, 2018 at 8:11 | comment | added | Ale..chenski | @Jtl, it is getting more and more as "X-Y" problem. You are not telling why "strong magnetic field" is of any importance in "test projects", nor why 100 uA (easly grounded off) is of any concern. | |
| Dec 7, 2018 at 8:07 | comment | added | Jtl | I bought this month 2 months ago hammfg.com/electronics/transformers/line/172.pdf It has so strong magnetic field.. so I bought the Toroid above. So if I got the 240 model, I'd still get shock if I or my instrument (accidentally) touch live to ground? btw.. help me find tranditional one with two separate coils because I can't find these anywhere | |
| Dec 7, 2018 at 8:01 | comment | added | Jtl | I also owned a traditional Hammond isolation transformer, but it is shell type where the windings share the middle legs. Do you know where I can find isolation transformer that uses the core type (where it is at both ends)? I can't find these. I know there are more core loss but need better isolation. | |
| Dec 7, 2018 at 7:58 | comment | added | Ale..chenski | @Jtl, note the marketing bullet on 169 model quoted by Jeroen3 which says: "Electrostatic shield between primary & secondary". This feature is not listed in 240 series. | |
| Dec 7, 2018 at 7:54 | comment | added | Jeroen3 | @jtl no. Still a toroidal. I have not seen those as isolation transformer. You need a normal iron core transformer with foil, or two separate coils. | |
| Dec 7, 2018 at 7:53 | comment | added | Ale..chenski | @Jtl, the 240 model is of toroidal type, so windings still go over each other a lot. Good isolation transformer has coils on opposite sides of magnetic core, where the coupling is much less. Unless you demand coupling data from manufacturer, you shouldn't expect anything. Why a 100 uA leakage is bothering you? | |
| Dec 7, 2018 at 7:48 | history | edited | Ale..chenski | CC BY-SA 4.0 |
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| Dec 7, 2018 at 7:47 | comment | added | Jtl | I plan to buy this Hammond 240 series hammfg.com/electronics/transformers/line/240 Is it full fledge isolation transformer and I won't expect to measure any voltage from any one of the output to the soil? | |
| Dec 7, 2018 at 7:44 | comment | added | Jeroen3 | @jtl Yes it still isolates. It just has poor common mode. True safety isolation transformers only have capacitive coupling to earth due to a metal foil between primary and secondary winding. | |
| Dec 7, 2018 at 7:40 | comment | added | Jtl | So if the only connection to the primary is via capacity coupling, do you still call it an isolation transformer? Even in ordinary full fledged isolation transformer, there is still capacitive coupling between the primary and secondary. | |
| Dec 7, 2018 at 7:37 | history | edited | Ale..chenski | CC BY-SA 4.0 |
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| Dec 7, 2018 at 7:15 | history | answered | Ale..chenski | CC BY-SA 4.0 |
