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VK3XX > INFO 06.07.02 13:58l 54 Lines 2246 Bytes #999 (0) @ WW
BID : E60947VK3XX
Read: DB0FHN GUEST
Subj: Re: SELSYNS ANYONE?
Path: DB0FHN<DB0ZWI<DB0CHZ<DB0ERF<DB0SON<DB0MRW<OK0PKL<OK0PPL<RZ6HXA<SP7MGD<
WB0TAX<VK3AVE<VK3FRS
Sent: 020706/0512Z @:VK3FRS.#MEL.VIC.AUS.OC #:25389 [Kilsyth] $:E60947VK3XX
From: VK3XX@VK3FRS.#MEL.VIC.AUS.OC
To : INFO@WW
Hi Warren and anyone else interested.
In answer to Warren's interesting question as to how they work I
eventually found the information in a copy of the ARRL Antenna Handbook
1982 edition.
I could remember the basic construction of two windings one being three
phase but I could not remember the precise configuration and construction.
So here goes and see the books for any further details.
The rotor of each unit is wound as an electromagnet similar to the rotor
of a synchronous generator or motor except that instead of being supplied
by DC each is supplied by single phase AC through slip rings. This
provides an alternating magnetic field. Both generator(or transmitter) and
motor (or receiver) are similar in construction, but the latter often has
an induction inertia damper like a flywheel on the rotor.
Both units have a three phase winding on the stator and these are directly
connected together in parallel as are the AC supply fed windings.
The rotor behaves as the primary winding and the stator as the secondary
winding of a transformer.
The action is such that the voltages induced in the rotor winding phases
of the transmitter are representive of the angular position of its rotor.
At the receiver end the rotor phases and voltages, which are the same as
those induced in the transmitter, will act upon the rotor to produce a
rotational torque on the rotor for any position of that rotor which is not
identical to that at the transmitter end. The only point where the induced
torque is zero is where the receiver rotor position is precisely the same
as it is on the transmitter. For any other position of the transmitter
rotor the torque induced on the receiver is in such a direction that it
drives the rotor to a matching position at which point it stops.
So there it is. A bit difficult to describe without a picture!
Have fun and please accept that it wont go round and round like a motor
and never stop!
Warren, thanks for making me go back to the books. We all take these
things for granted and tend to forget the fundamentals.
Cheers and
73 - GORDON, VK3XX @ VK3FRS
Message timed: 15:05 AEST on 06 Jul 2002
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