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Power cut
On 22/08/2019 08:14, Steve Walker wrote:
On 22/08/2019 07:26, The Natural Philosopher wrote: On 21/08/2019 20:32, Steve Walker wrote: On 21/08/2019 20:02, tony sayer wrote: In article , Martin Brown '''newspam'''@n ezumi.demon.co.uk scribeth thus On 20/08/2019 23:04, Max Demian wrote: On 20/08/2019 19:21, Andy Burns wrote: Max Demian wrote: How do that with sodding great dynamos all round the country that all work in different ways? By all running at 50Hz, and getting them into sync before joining them to the grid. I heard on a radio programme recently that the generator people are relaxed about the overall synchronisation and they don't have clocks saying "electric time" and "actual time" in the power stations so that "cooker clocks" might not be reliable. Does anyone know if this is true? There must be loads of synchronous timeswitches about, and quite a few clocks - I think I saw one in a local hospital. They are legally bound to keep the twenty four hour average extremely close to 50Hz - ISTR the exact tolerance is still an official secret. Excursions 0.1Hz either way are not uncommon at times of heavy or light loading. They play catchup in the night and run slow in daytime. A synchronous motor mains clock could be running 0.2% slow for most of the working day so in an 8 hour shift it could drift by about a minute in the employers favour. These days most modern systems are crystal controlled and drift around 15s a month or less if trimmed. Cooking wouldn't notice a 0.2% error in timing. GPS would! Do that many clocks use the mains these days?, went to the leccy wholesalers the other month quite a good range, all battery Radio ones and aren't they using much the same or quartzÂ* on cookers and the like a lot nowadays?.. Probably any mains powered clock. Why bother using the crystal, when mains frequency (over time) is more accurate? The crystals are then only used for battery back-up. One very simple reason. Cost. A synchronous motor and gearbox costs more than a quartz crystal and a chip and a stepper motor. Or digital LCD display. Most mains clocks are digital these days and do time themselves from the mains. Built into ovens, cookers, boilers or just stand-alone bedside alarms. Wall and mantlepiece clocks tend to be battery powered and so are purely crystal based (although our wall clocks are good, old clockwork). I dont think most people undersatnd engineering cost, but them most peole havent designed stuff to be mass produced and sold. Most mains clocks are not run by synchronous motors now, they are LCD or LED and controlled by a single chip. However, the mains is there and it makes more sense to time from that (for the accuracy) and so they do. A crystal costs next to nothing. Why would they use mains?It will end up costing more One of the big drivers for electric car windows is that a motor and gearbox and switch is a little bit cheaper than a handle. Is it? Fair enough, but why did we have many years with cars only having electric windows as optional extras or only in the front? Manufcturers stuck in teh age of te dinosaur/EU Why do we have touch screens?Â* Menus? because they are cheaper than proper controls. Yes. Not just parts and production costs though. A big driver is that software is easy and "cheap" to add new features to or to provide different options for different trim levels of cars or levels of other consumer goods. Cost drives engineering development. And in te comnsumert market, creeping featursim and novelty. Useless features are added that dont cost anything more than a bit of software, to make everything massively over complicated, which appeals to low brow users. I am perfectly happy to have lots of extra features, as long as they don't get in the way of the basic, day-to-day operation - and too often they do. Exactly. I simply cant be arsed to learn how to set a modern microwave fpr '3 mintes at half power please' when its all buttons and menus, Its 1 second on two rotary dials here. Commercial microwaves have knobs The prize for the worst user interface in te workld gose to smart phones I missed about 30 calls before I worked out how to answer it What ever happened to 'lift handset and talk' SteveW -- Labour - a bunch of rich people convincing poor people to vote for rich people by telling poor people that "other" rich people are the reason they are poor. Peter Thompson |
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