Categorizing things...

Comments on whether you prefer to categorize in one of the following ways:-

• - Single - a very existential approach - to be or not to be...
• - Dual - It's either this thing or that [only two choices]
• - Triple - It's this or that or the other [no one likes to be the other]

I found that categorizing things in hierarchical groups of 3 enables us to make sense of prioritization with a minimum number of levels. For example the hierarchy shown above Things -> {Numbers{Even, Prime,Other}, Colors{Purple,Cyan,Blue}, Shapes{Circles, Rectangles,_}}.

Remote Control Modes - Local vs Remote

This amounts to a short note really.  

Nothing too mind bending, just the usual confusion with language we sometimes have....

Often Control Selectors and Mode switches are provided to assist off-normal operation or maintenance.

These days most control is done remotely, with Local control being the abnormal case.

Local control refers to the control you do when you are remotely located ? Doesn't make a lot of sense linguistically at least. 

So LOCAL really means LOCAL to the controlled Equipment.  REMOTE means controlled remotely from the MCR/PCR/MCC etc. normally a remote central location.

Of course we have confused the issue somewhat with the choice of language in SCADA where Supervisory control is managed from the REMOTE control location, and the Remote Terminal Units [RTU] are provided in the locality of the equipment.

So what of a Remote/Local control switch ?

A Remote/Local control selector switch can often be situated in proximity to the controlled plant [i.e. LOCAL to the equipment] and allow an operator to take control locally and avoid the need to interact or accept remote supervisory commands.

Switching the Selector to REMOTE allows the equipment to be controlled REMOTELY from a SCADA Master Station.

The important point to remember is that LOCAL always refers to the locality of the actual equipment.

If you have a particularly fine example of local control remote/local selector switch that you would like to contribute a photo of, please feel free to make a comment or send an email.

Happy Christmas.

Chris Smith

Sydney, Australia

Harry's Christmas Indigo collection

Water was what Harry was worried about. More specifically the effectiveness of it at his secret Indium mine site. Harry had something going wrong with the collection of Indium from the falls water, which was bad. His whole process was based on collecting the metal after heavy rains in a remote area.

Harry had come up with an autonomous process which extracted the rare metal directly from a stream of water flowing over the zinc/indium ore bearing rocks. Still unsure as to why there would be an unusually high concentration of Indium, Harry was not bothered.  All he had to do was make sure the tanks collected the water at the right time and flow rate and then run a solar powered concentration process on site remotely.  Every year he would go up the mountain and collect, just in time for Christmas.

This year things were not working out. The collection timing was wrong, all the equipment was working, but the collections were just not making it.