Local light control - timer source needed

[Hewlett]

For about 40+ technical rooms (probably more), we need to implement some light-power saving features. Light load 500-2000W
There are already switches at (mostly 2) entrances, so 3 wire + earth is available from end to end.
The spaces are visited from daily to monthly.
Routine visits less than 1 hour. Maintenance visits 3-10 hours.

Precence sensors was considered, combined with timers (all presence sensors we found have less than 30 min off delay), but many of the rooms have moving and/or hot machinery, fans etc that may make this problematic...+ the cost makes this an issue. (Each sensor takes a quite limited load, so we would need to add sensors or relays, so we basically scrapped this, as we would prefer one standard solution for all.)

Currently we look at having a small box with a pushbutton, impulse relay and 4hour off timer in one end, and an impulse switch in the other end.
One backdraw for this is that the technicians will soon learn to switch off/on the light every time they visit if it's on. (And this may be annoying for the more frequently visited rooms...)
Have looked at standard "staircase" timers, but it appears they are all with relatively short time (max 1 hour maintenance mode).
Would prefer to leave the tech's "in control" for normal visits, but switch off light automatically after 4hours if they don't.
Can't believe there's not a cheap standard product for such a "common" application, so I'm throwing it out here...

Functionality wished:
Short pulse (pushbutton) - light on or off
Timer with Off delay switches light off after a delay (adjustable 1-10 hours)
Long pulse (>2 seconds)resets timer while light is on.

Cost....well, joy is that we reach the estimated payback limit at about 100EUR / room, so we may have to wait for further kWh increases to justify this whole thing...
...anyone?

 

[itsmoked]

I really can see no option other than PIR sensors. Timers have the ability, and will be leaving someone in a hazardous situation in the dark with moving machinery. All you need is one injury from this to tank the costs of implementation a hundred times over.

At one place I worked they put in a PIR sensor in the restroom. The idiot landlord set them to 1 minute.

We were all amazed however, because if the lights went out plunging us into pitch darkness, all you had to do was wag your little finger. It was quite amazing actually.

With many of these sensors you can mask them from seeing certain areas,(moving machinery).

I think there are also ultrasonic sensors that put up standing fields that are disturbed and hence detect the motion.

Whatever you use I believe you will need the method to detect a person moving in the room to re-trigger the timer. 10 minutes to 30 minutes should be plenty.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Hewlett]

Thanks Keith,
forgot to mention, the facilities also always have emergency lighting enough to move around in the rooms, and we're not allowed to switch those.
Agree prescence detection is the "best" solution, but unfortunately a bit beyond the budgets for this situation. It's of course all up to budget owner, but I hate to think of light being on 24/7...we have implemented PIR and HF sensors (Steinel) in some other facilities, and they are sure performing well, and the PIR's have good inserts to screen sectors. They are actually one of the options still considered, as they also have a "maintenance mode" built in....triggered by "doubleclicking" (2 rapid interruptions of supply to sensors)...

 

[jraef]

You can do it with a Siemens LOGO! programmable relay. It has the built-in functions you need. Output relays are rated 10A 250VAC, but you didn't mention your L-N voltage (if N. American 120V, 2000W would be a problem if it's one lighting circuit). The LOGO! was originally designed for just such an application. We use them in all of our offices almost exactly as you described.

Siemens LOGO!

 

[SteveMeisel]

We were looking into the same thing. First stated small by looking into putting the lighing just in our copy machine room (more of a closet) on one of those motion sensors that replaces the light switch but the payback turned out to be 7 years. Cheaper to leave the light on even though is seems such a waste. At night they just have one of the maintenance guys go around and turn off the lights instead.