LightingControl

[pithpal]

Hi Everybody,
I would appreciate, if you could help getting the concept of lighting control using "Building Automation System". I just need a brief idea, I beleive than I will be able to understand.
I am an engineering in training and have been asked to suggest a retrofit for an existing building lighting control. The building has 7 floors and each floor is defined as a zone by the "Honeywell BAS". I looked in the electrical room, which has both relay panel and circuit panels.
My question is in regard to concept of controlling light fixtures. I will start with the simple idea of a T8 flourscent fixture. Here is what I think it is, please correct me if I m wrong.
" A FLOURSCET LIGHT HAS A BALLAST AND DEPENDING UPON THE VOLTAGE 120 OR 347 V. IT IS POWERED. NOW WHEN THE BAS HAS TO TURN OFF A BUNCH OF LIGHTS OF OR ONE COMPLETE FLOOR, DOES IT TAKES THAT CIRCUIT PANEL OUT OF SERVICE OR USES A SIGNAL TO LATCH THE RELAY PANEL TO CUTOFF THE POWER. IF IT USES RELAYS THEN DOES IT MEAN , IF THERE OR 200 FIXTURES THAT MEANS 200 RELAYS. THE OTHER THINGS , IS IT POSSIBLE THIS BALLAST HAS A CONTROL SIGNAL OPTION LIKE DIMMABLE BALLASTS HAS. THE BUILDING IS 20 YRS OLD, I AM NOT SURE AT THAT WE HAD OPTION OF SENDING A CONTROL SIGNAL TO A BALLAST FOR TURNING ON AND OFF. IF THESE ARE SIMPLE BALLASTS HOW THEY ARE BEING CONTROLLED EITHER BY TURNEING OFF THE POWER TO BALLAST AND HOW MANY RELAYS CAN HANDLY HOW MANY FIXTURES AS RELAY ARE AT THE MOST 10 VA LOAD HANDLING CAPACITY.AM I CORRECT, IF NOT , PLEASE HIGHLIGHT HOW RELAYS AND POWER PANEL OR COORDINATING EACH OTHER FOR TURNING THE LIGHTS ON OR OFF."

Any comments will be highly appreciated.

Thanks

 

[pithpal]

I forgot to ask one more thing besides my this question. I have a spec for a heavy duty lighting control relay 20 A.
It say rated for 20 A 30,000 electrical operations.that measn this realy can turn on or off a ballast only 30000 times. if a light is turned on or off 5 times a day.
that measn 150 times a month and 365*12*150 times a year
that comes 657000. So this relay would not work even for a year. I am sure I have a screwed some where. Please correct.
Thanks

 

[davidbeach]

Think about your numbers. Just because you get an answer on your calculator doesn't mean it is correct. A 30000 operation relay will last for many, many years. How would a lighting control device be expected to operate an odd number of times per day?

 

[itsmoked]

And if you said 150 times a month why would you then multiply that by 365? There aren't 365 months a year are there? (Or has everyone been holding out on me...)

Further more if a relay sez 20A 30,000 "ELECTRICAL OPERATION" That may mean that relay can switch 10A 200,000 times. You need to look at the "MECHANICAL OPERATIONS" for the absolute life of the relay.

You need to examine the ballasts your building has to see how they are controlled. Don't ask us!

Generally you don't turn off each and every ballast one at a time. One contactor would handle X units.

If the automation system has low current relays then they are only controlling the bigger relays (contactors).