Re: XFMR Connection Question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Rajesh Seenivasan" <rajeshkvs-at-hotmail-dot-com> 

Greetings,

I have 3 ferrite cored transformers.
primary rating- 220V peak to peak, 5Amps
turns ratio- 1:10

These three transformers are identical - same ferrite material, same no of 
primary and secondary
turns and same kind of wires for primary and secondary. I assume that 
inductance values will
also be very close.

Mr.Alfred says,
"When connecting transformers in series or parallel you should try to
match the transformers as closely as possible and make sure that they
are phased correctly!"

I hope I have matched the transformers as closely as possible. How do I 
correctly phase the
transformer ? Please explain.

Thanks in advance.
-Raj.




Original message:
-----------------------
From:   Alfred A. Skrocki[SMTP:alfred.skrocki-at-cybernetworking-dot-com]
Sent:   Thursday, June 26, 1997 2:21 PM
To:     Tesla List
Subject:        Re: XFMR Connection Question

On Sunday, June 22, 1997 6:10 PM mikey1
[SMTP:mikey1-at-gladstone.uoregon.edu] wrote;

>Greetings,
>
>I am considering the question of the connecting three different neon
>sign transformers with the following ratings to power one coil:
>
>12,000V 30mA.
>  9,000V 30mA.
>  6,000V 30mA.
>
>My question is, would it be possible to connect all three in parallel? If 
>I did so, would I expect 9,000V at 120mA., or have I been around the
>solder too much?

You've been around the solder too much! NEVER connect differing
voltage transformers in parallel or series! Most probably what would
happen if you connected those transformers in parallel is the 6KV
transformer would blow since it would have less insulation on the
secondary windings. Also considder that if you connect two differing
voltage transformers in parallel the higher voltage transformer will
be effectively driving the lower voltage transformer backwards while
it is also being driven forwards by the mains. IT WILL COOK the lower
voltage transformer!

>Another question is would I be able to connect them in series?  If so,
>what would be the resulting output?

IF the current rating is the SAME you can connect two differing
voltage transforers in series ONLY IF their insultation can hold
under the higher combined voltage.

When connecting transformers in series or parallel you should try to
match the transformers as closely as possible and make sure that they
are phased correctly!

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