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Old 28th July 2003, 04:31 PM   #1
316a is offline 316a  England
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Default Toroidal Transformer Insulation Rating

Hello Folks !
I can't find my megger but need to know the insulation rating of a transformer . Unit is a 115/115 primary 50VA Talema , unable to find the info on the website , would guess much-of -a-mutchness between manufacturers . Any ideas ? Thanks for your time

316a
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Old 28th July 2003, 04:46 PM   #2
tiroth is offline tiroth  United States
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http://www.amveco.com/Power_Transformers.htm

Low Profile PC Mount:
Safety standard certifications (UL 506, UL 1950, UL File E122978, E138299)
VDE 0805, IEC 950, EN 60950
UL recognized for insulation Class A (105C). Meets all requirements of Class E(125C)
Hipot testing at 4000V between primary and secondary. (VDE0550)
Maximum ambient temperature of +60C for 1.6VA-25VA, +40C for 35VA and 50VA models

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Safety standard certification (UL 506).
UL recognized for insulation Class A (105C). Meets all requirements of Class E(125C)
Hipot testing at 4000V between primary and secondary.
Maximum ambient temperature of +60C

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Old 28th July 2003, 04:51 PM   #3
316a is offline 316a  England
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Default Thanks !

Well spotted , could not find the info myself .

316a
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Old 28th July 2003, 05:09 PM   #4
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Default Re: Thanks !

Quote:
Originally posted by 316a
Well spotted , could not find the info myself .

316a
May I enquire as to why you needed this information? If you are planning on using a transformer beyond it's rated capacity (IE use this transformer in a tube circuit) I would suggest that you not do this.

Scott
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Old 28th July 2003, 05:32 PM   #5
316a is offline 316a  England
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Default Why not ?

I have used toroids for the last year succesfully in push-pull , parafeed and recently driving small ESL panels **without** problems . The only 'problem' is the bass driving cone drivers which is a tad light but who cares with a >1khz ESL panel ! I'm about to build a 20 x 36" panel which will require substantially higher drive (2500v p-p) hence the query and I doubt I'll be able to get enough drive directly from the amp's anodes . Why would toroids be a poor choice in your view ? When I find my megger I'll run some more tests to concur with the info on the Talema site

316a
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Old 28th July 2003, 05:57 PM   #6
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Default Re: Why not ?

Quote:
Originally posted by 316a
I have used toroids for the last year succesfully in push-pull , parafeed and recently driving small ESL panels **without** problems . The only 'problem' is the bass driving cone drivers which is a tad light but who cares with a >1khz ESL panel ! I'm about to build a 20 x 36" panel which will require substantially higher drive (2500v p-p) hence the query and I doubt I'll be able to get enough drive directly from the amp's anodes . Why would toroids be a poor choice in your view ? When I find my megger I'll run some more tests to concur with the info on the Talema site

316a

Hmmm..it's typically a safety thing. The reasons that any transformer is tested to say 4000V hi-pot is to show a sufficient safety margin for the insulation. The insulation that passes for such a test will be very safe at lower voltages over a very wide range of temperatures and humidity levels.

Scott
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Old 28th July 2003, 08:17 PM   #7
316a is offline 316a  England
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Default What problem ?

Hello ,
Nothing to worry about , here in the UK , the weather is less variable than your side of the pond , what humidity ? Tx has been running for the last 30 mins , no heat , no fuss the **wrong** way round . I'm getting 1200v across the primary via isolating transformer on the secondary . With a 400V valve HT transformer I'm getting 1808V , same again , no problems , sparks , heat or near death experiences . The megger test will be the decider though .

316a
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Old 28th July 2003, 08:24 PM   #8
dhaen is offline dhaen  Europe
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Default Safety or performance?

The critical point here is surely:

If the transformer were to break down, would it cause any safety hazzard, or just a horrible noise.

If the former - don't. If the latter, no problem.

Cheers,
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Old 28th July 2003, 08:40 PM   #9
316a is offline 316a  England
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Default Re: Safety or performance?

Quote:
Originally posted by dhaen
The critical point here is surely:

If the transformer were to break down, would it cause any safety hazzard, or just a horrible noise.

If the former - don't. If the latter, no problem.

Cheers,
I doubt anything really bad would happen , the latter will probably be the case at worst , I've only seen transformer insulation break down due to heat in the past . Arcing is the main enemy at these voltages


316a
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Old 28th July 2003, 08:56 PM   #10
316a is offline 316a  England
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Default Re: Safety or performance?

Quote:
Originally posted by dhaen
The critical point here is surely:

If the transformer were to break down, would it cause any safety hazzard, or just a horrible noise.

If the former - don't. If the latter, no problem.

Cheers,
I've only seen transformer insulation break down due to heat in the past usually within telecoms equipment that had been switched on since the year dot surely a fus on the HT rail should do the trick ?

316a
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