ClausT Skrev:COSC for quarts ure kræver vel endnu større nøjagtighed end for automatiske ure?
... Ja! osse i den grad.
På siden:
COSC - Contrôle Officiel Suisse des Chronomètres, har jeg "sakset" nedenstående.
What exactly is a chronometer ?
The term chronometer is often wrongly applied to timekeeping instruments fitted with an additional mechanism that may be set in motion by pushbuttons to enable measurement of the duration of an event.
Such an instrument is in fact a chronograph or chronoscope. It may of course be chronometer-certified, provided it meets the criteria set for the standard.
In its technical regulations, the COSC has included an additional condition, namely the permanent display of the seconds.
A chronometer may thus be defined as follows:
A chronometer is a high-precision watch capable of displaying the seconds and housing a movement that has been tested over several days,
in different positions and at different temperatures, by an official neutral body (COSC).
Each chronometer is unique, identified by a number engraved on its movement and a certification number given by the COSC.
Each movement is individually tested for several consecutive days, in 5 positions and at 3 temperatures.
Each movement is individually measured. Any watch with the denomination "chronometer" is provided with a certified movement.
Mechanical chronometer
ISO 3159 provides the definition of a wrist-chronometer with spring balance oscillator.
Only movements which meet the precision criteria established under ISO 3159 are granted an official chronometer certificate.
Movements are tested for 16 consecutive days according to a tests panel.
Every day, including Saturdays and Sundays, movements are measured and rewound.
• Based on these measurements, 7 eliminatory criteria are calculated.
• If and only if all these criteria are met, the movement is duly "chronometer-certified".
> Please refer to the table summing up these criteria and their degrees of tolerance:
Quartz chronometer
No international standard has so far been issued regarding electronic quartz watches.
Based on ISO 3159, the COSC has drawn up a set of testing prescriptions applicable to quartz chronometers which govern their performances in the same way as for mechanical chronometers.
Taking account of the specific technological characteristics of these products, the COSC has adapted the tests and precision requirements.
This called for the development of special quartz movements in order to meet these new requirements.
It has become compulsory for them to be equipped with an electronic system compensating for the variation in the frequency of the quartz according to changes in temperature.
A new-generation quartz chronometer is therefore 10 times more accurate than a conventional quartz watch. Moreover it is a very exclusive product manufactured on a low scale.
Each quartz chronometer is tested for 11 days, in one position and at 3 temperatures, as shown in the table below:
In addition, throughout an entire day, it is subjected to 3-dimensional rotations causing it to repeatedly assume all spatial positions.
Finally, it is subjected to 200 shocks equivalent to 100 G (100 times stronger than gravity).
Based on these measurements, 8 eliminatory criteria are calculated. If and only if these 8 criteria are met, the movement is duly "chronometer-certified".
>Please refer to the table summing up these criteria and their degrees of tolerance:
Såfremt kvartsure blev kronometercertificerede på de mekaniske ures præmisser, ville anskuelsen af dette som "varm luft" nok være rimelig.
Men kravene til et kvarts kronometer er ekstreme, i forhold til de mekaniske krav.
COSC skriver:
Nyere kvartskronometre er derfor 10 gange mere præcise end konventionelle kvartsure. - Yderligere er de et meget eksklusivt produkt - produceret i små serier.
Egne erfaringer:
I min "samling" findes et af de beskrevne eksklusive produkter.
Sidste batteriløbetid var fra 19. december 2008 til 9. januar 2010 = 386 døgn. I den beskrevne periode tabte uret 11 sekunder, svarende til: 0,85 sek/måned.
Ifølge urets specifikationer må det afvige ±1 sek/måned. - Faktisk smukt klaret af et ur, der har gået konstant i 33 år.
Batterilevetiden er ikke meget at skrive hjem om.
Dog må den vurderes som tilfredsstillende, når det tages i betragtning, at uret på 2,4 MHz arbejder 75 gange hårdere end et konventilonelt 32 KHz kvartsur.
Synes egentligt ikke, at urets præstationer er "varm luft" - og "bekender" hermed glad og gerne min interesse og passion for high end kvartsure, og opstiller:
Geodoc's teorem: "Mange mekaniske ure er interessante - Men ikke alle interessante ure behøver være mekaniske" 
Med venlig hilsen - Geodoc
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