Re: MOT's and series operation

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

Original poster: "tesla by way of Terry Fritz <teslalist-at-qwest-dot-net>" <tesla-at-paradise-dot-net.nz>

Greetings Jerry et al

MOT's can work very well as Tesla Supplies and there has been quite a lot of
list activivty and WWW site data.

I have run sucessfully 6 MOT's in a 3 secondaries per side centre ground. I
recall someone saying they had achieved 8 in a similar arrangement.

There have been some clever schemes using multiple MOT's to gain extra
insulation and perhaps their designers will post.
It is my experience that those "improved" schemes are not needed provided
the elevated secondaries are in oil.

I personally advocate earthing the core of ALL Mots to place a barrier
between the mains side and the HV side. I have seen differing opinions on
this point however as if it is floating you effectively can spread the
voltage stress out between core to primary and core to secondary gaps.

You will need to ensure that parallel groups have the same secondary
voltages. You can mix and match in the series MOT selections.  In  120V land
wiring for 220V would seem to be a better option than 120v. In the short
term I think you will have your hands full without resorting to paralleling
arrays as the power available is very high from single arrays

I have found it is possible to run one 1/2 of the MOT stack directly off the
mains and then ramp up the other 1/2 on a variac.(After previously tuning
and ensuring correct operation with full variac control)

I wash my MOT's in alcohol prior to potting in oil and dry them either in a
very low oven or in the sun afterwards as cleanliness is critical in this
matter.

Many containers possible for oil and MOT, I've use 6" low pressure PVC
Plumbing pipe and associated caps for containers. Strong and leak proof but
a little costlier than some other systems. It's modular nature is great for
varying the size of the stack and moving it around.

I've noticed that the insulation clearance from the secondary to core varies
between MOT brands and I select outer MOT's for best secondary to core
clearance.

Good Luck.

Subject: MOT's


 > Original poster: "JERRY ASHLEY by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <jerryla-at-ix-dot-netcom-dot-com>
 >
 > I recently became the proud owner of a dozen MOTs.  I've been an
 > electronic tech and a ham for over 40 years but I have no experience
 > with MOTs.  I am wondering, what is the best way to connect these guys
 > together for a spark gap Tesla coil power source (in oil).
 >
 > I want to wire 'X' transformer secondaries in series for a higher
 > voltage and then connect several of these groups in parallel for more
 > current.
 >
 > How many secondaries can I safely connect in series?  Any 'best way' to
 > wire the primaries.  Primaries can be wired for either a 110 or 220 volt
 > source.
 >
 > Tnx, Jerry  -  W8UJX
 >
 >
 >