This is indeed an interesting application of PLCs, but I am puzzled as to why it had to be that complex. That may be due to having the heating outlets tied to the lighting circuits, I suppose, which may have been cheaper when the lot was first built. Otherwise, a simple system to switch on the power only when the ambient temperature demanded it and only at the times needed would probably have been much less expensive. But possibly there are a few details not mentioned that would have mandated the PLC choice.
20 years ago whilst working for Idiot Blinking Management I realised running the cooling compressors on a walk in thermal chamber that was designed to be able to reach -80 and +150 C when it was only ever run at +75 to condition Hard-Drive casings was just plain stupid. I discussed it with my line manager, and his manager, was given a small budget and designed some really simple timer relay circuits, a PLC would have been nice, but back then simplicity and low cost was required.
We installed it on several different chambers and over several months cut power costs significantly. So we converted the whole plant, and not just power but wear saving soon mounted up. When my idea was put forward for the I'm Bloody Marvelous employee idea's scheme the plant managements answer was it wasn't worth it, and I was 'only a fu*king contractor'. 6 months later one of the plant managers put it in under his name and 5% of the savings made by modifying every thermal chamber world wide owned by Incredibly Badly Managed was his...
I hope the supervisor gets at least some credit for this work, beyond those in the technical field, and it's uptake by others, but somehow I doubt those in charge will care.
This was a very interesting use of a PLC and interfacing to cycle block heaters. One thing that sort of irritated me was the initiative to save money was only driven when taxpayer funds became short. Why is it government entities only come up with good solutions when the taxpayer is fed up with feeding the behemoth?
Kudos to the bus guy! I now have at least one example of government doing something right.
Now if the spendaholics in DC could find ways to save money???
Amanda, this is a great story. The solution saves money on energy and the solutions used to keep costs down are really innovative. I worked with an electrical contractor once who, when show a Zigbee based building controll system said, wait a minute now. He was seeing his business going away, since wiring is a major cost and very labor intensive.
The other aspect of this solution that many people overlook is the need (or lack thereof) to get a PC to run the system. The whole premise of clould computing is that businesses have to purchase computer equipment that meets peak needs, while they end up spending a lot of time running at less than a quarter of their capacity. This is even more true of PCs in offices. Hats off to the Building Maintenance Supervisor.
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