[Info-vax] VMS and the Internet of Things (IoT)

[David Froble]

Chris wrote:
> On 09/12/16 18:55, johnwallace4 at yahoo.co.uk wrote:
> 
>> The smart meters being rolled out in the UK are required to
>> have, as well as the remote metering stuff, a remotely
>> controlled power-off switch. No UK law currently permits use
>> of this off switch, but that can be changed at a few hours
>> notice when the state of emergency arises.
> 
> Forgot to mention that, but does raise an interesting
> question from an engineering pov. They need to be able to
> switch a 60-100 amp load, the usual incoming fuse rating
> here in the uk. They can either use an electromechanical
> contactor / relay, or a solid state switch. A relay of
> that rating is physically bulky, with large silver or silver
> alloy contacts That solution would drop insignificant
> voltage, but would need to be always on, wasting ~10Va each.
> Multiply that by millions of meters = megawatts of wasted
> power. While it could be normally closed, ie: contact closed
> unenergised, it's doubtful if there would be enough contact
> pressure to handle the current rating. If a solid state
> relay is used, at that rating, expect to drop 2-3 volts. So,
> at a 100 amp load, that relay dissipates 2-300 watts, which
> would need a very big heatsink or foced ar cooling to
> prevent meltdown and er, who will pay for that wasted power ?.
> 
> That's just one of the things that sprung up while reading
> the spec. Devil is in the detail, as usual, but the whole
> project is completely over the top.
> 
>>
>> Do people want a Window box in charge of this capability?
>> When a Windows (or other) Update disables the USB-serial
>> adapter which is likely a critical piece *somewhere* in
>> the setup? Or any of the other usual unfortunate stuff
>> you get with the usual high volume low value commodity OS
>> used in a place where a high volume low value commodity
>> OS don't fit right?
> 
> Windows might be fine for front end user interface, but one
> would hope that any safety or security critical system
> would have a fully hardened and avionics grade approved
> os of some sort. Doubt it actually happens though :-)...
> 
> Chris
> 

In this world, financial people seem to drift to the top of things.  (Shows how 
stupid the human race is.)

If you ask a financial person to make a decision, it will most times be a 
financial decision.  (Works well when an engineering decision is needed.)

Avionics grade (that means good)?  But it's so much more expensive.  (See above 
concerning who's at the top, and financial decisions.)

Makes you wonder how we ever got out of the caves?  (Perhaps the financial 
people got lost and couldn't find their way back to the caves.)