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Re: FREE NST's



> Original Poster: "Charles Arruda" <carruda-at-channelseek-dot-com>
> 
>> 7. PHASE YOUR NST's (for instructons on this just ask the list, or email me
>> if you don't know already)
> 
> Is there a simple way to do this?  What happens if they are "out-of-phase"?
> Is there a "lead-lag" circuit to correct phase-shift from mismatched
> transformers?

By "out-of-phase" he means by 180 degrees, i.e. with the secondaries or
primaries hooked up anti-parallel instead of both parallel as they should
be.

To test for correct phasing, you can hook one side of the secondaries
together and put a voltmeter on the other two bushings, then apply a VERY
LOW VOTLAGE (1 or 2 volts) to the primaries and see what the voltmeter
reads.  It should be near zero, but if it's a high voltage (like a few
hundred volts) you've got them phased wrong.

NOTICE: This method involves hooking the secondaries in series, which will
kill one or both of the transformers if you input more that 50% of your line
voltage or so.  Also, input only a couple of volts. If you input more than 3
volts, but be sure to use a voltmeter than can handle the voltage if you
have them hooked up wrong. For example, input of 6.3 volts into a pair of
incorrectly phased 15000 NSTs would give a difference of:

    Input 6.3 volts * 15000/120 * 2 =   1575 volts!

-Adam
adamsmith-at-mediaone-dot-net