[time-nuts] Features of a Precision Clock?

[Dave Brown]

Bill Hawkins said (among other interesting stuff)

> Why not use automatic frequency control? Because the controllers
> in the different stations would fight each other, because they
> are tied together by the synchronous network. In other words,
> it is not possible to regulate a stable speed/frequency with
> more than one integrating controller - and one controller can't
> regulate enough power to stabilize the network - unless the
> controller is a dispatcher able to tell many stations what to do.

I posted brief details here last year (22/8/05) of just such a system 
that was tried here in NZ some time ago - to reiterate the relevant 
text....

*******
I have here the remains of an attempt in the early seventies to bring
this type of system up to date - it comprised an HP 105 series quartz
reference, a K20 - HP 5280A up down counter and an HP 5321B clock.
The up down counter was driven from 100 Hz signals derived from both
the 105B and the power grid. An HP 6933A D/A converter on the BCD
output from the counter had its plus/minus 10 volt output interfaced
to the generation plant speed control.  The 5321B clock reading was 
initialised from
the local time service (radio time pips) and then used as a reference 
for fine tuning the
'control system' (the D/A converter to generator speed control 
coupling) so the up down
counter stayed at or near zero reading and power grid time ran in sync 
with
national standard time.
I dont know how successful this system was but I think it was in
service for several years at a designated system control station.

 I have the up down counter and  the D/A converter almost fully
operational again- but only have parts ratted circuit boards from the
5321B clock and I never got the 105B.

*******
By way of update--
I have some of the original system design docos regarding this scheme, 
including notes from HP outlining their proposal in response to the 
original call for tenders etc.
Makes interesting reading.
And the 5280A up down counter IS now working properly-albeit sometimes 
erratically, due, I think, to the poor choice of multi pin connectors 
used between the pcbs and the front panel BCD switch arrays.

 Cheers
 DaveB, NZ




-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.407 / Virus Database: 268.13.0/465 - Release Date: 6/10/2006