Re: XFMR Connection Question

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

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 

The "rules" (guidelines) about connecting transformers in parallel and
series don't necessarily apply in the case of transformers with huge amounts
of leakage/ballast inductance.  One could hook a 9kV and a 12kV neon
transformer in parallel without much hassle.. Sure, it's not going to
perform like two identical transformers in parallel, but, under load, these
act more like a constant current source than a voltage source.

Under no-load conditions the parallel 9 and 12 will put out 11.5 kV.  So,
you have an insulation problem on 9 kV unit.  There will also be some power
dissipated in the resistance of the windings due to the current flowing
between the transformers.


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, February 14, 2004 11:06 AM
Subject: Re: XFMR Connection Question


 > 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!
 >
 > _________________________________________________________________
 > Raja Ravi Varma paintings. Buy art prints.
 > http://go.msnserver-dot-com/IN/42737.asp At MSN Shopping.
 >
 >
 >