Building Automation System

Hi all...
Can anyone tell me about BAS (Building Automation System) I have read some products of BAS. Can we use PLC (SLC 500 serries for example) to do this??? I want to integrate the AHU (Air Handling Unit), Fire System, Access Door, Lift (elevator) System, utility water pumping and distribution system, electrical power consupmtion monitoring system, Lighting system all in one integrated system (monitored via an MMI).

Your help, would be greatly appreciated.
Thanks
-ade-

You can do all of this with a PLC. Whether or not a single SLC-500 can do it depends on the I/O count and so on.

I would personally be reluctant to do the fire alarm system as part of this. There may be some code and safety issues involved. I think you would be better off using a special purpose fire alarm system as the primary contro, and simply monitor it with the PLC.

Thank you for the suggestion, I noticed. I'll learn more about it. Thanks

I believe the fire alarm system must be standalone via a recognized controller approved for this operation. However I am not positive on that

Ade,

Check out http://www.aamatrix.com/

Many options are available, and data can be collected from the system rather easily.

A lesson learned the hard way:

Project was control of air handling and heat exchanging of a large hydraulic pump room. Room requried cooling year round, so system staged an two compressor A/C system, air/chilled water heat exchangers, economizers (wintertime cold air inlets), and oil/air heat exchangers to recover heat in the winter time.

The PLC did not support online programming. Hindsight has been painfully clear.

Factor this into your choice.

Where I work we have computer controlled building (SIEMENS). Controls 3 chillers and associated pumps 11 (?) air handlers (with temp and humidity control), lighting, tied into elevators, fire alarm, and (I think security). It is so complicated Siemens has to maintain it - no one on site is qualified (they just love jobbing out by the way).
Takes almost 3 hours to reset everything in case of power failure - yes there is a diesel genset 250KW.

Oh they have a fancy screen with basic system drawings BUT
the operaters trust the computer too much.
EXAMPLE filters in ventilation are change only when pressure drop is too high - who calibrates these to ensure accuracy -- supposedly Siemens.

I think this system is too automated or at least not enough manual controls.
EXAMPLE diesel gen set has no reostats, hand throttle, etc to allow manual control. IF it were mine I would be able to start the thing and get on line even if the factory solid state panel melted down.

The computer is only as good as the sensors. In one case I have seen the computer said a damper was open - after much wrangling someoone FINALLY checked the damper - linkage was disconnected - damper was shut.

Three mile island occurred because of poor (sensor)indication design.

The point is computer control is great when it works - there is no better control -- what is your fallback plan when it does not??

Dan Bentler

PLC's are not the best solution for the building automation. You wanna take a look at Andover controls. www.andovercontrols.com

This would be a leading system in U.S.
Using PLC's in conjunction with Andover controls makes a lot of sense in specific applications. For example if you are going to have a CoGen system in your building I would not want to control it with an Andover system.
In terms of lighting controls one system that is not widely used in U.S. is a DALI network. However this system is widely used in Europe and is finally getting some exposure here in the U.S.
I recommend that you look into it.

We have Siemens Apogee system with "Insight" as the HMI. I call it BMS (building management system). It's very similiar to a industrial DCS except there are a lot of logics that are in the local controllers. Hardware cost is less then your high $ AB system. There NOTHING I see that can't be better handled by a PLC system. Of course, that coming from me, a PLC person. You can also find information over at www.hvac-talk.com, they got a Control Section that you can read and ask questions.

ade said:

Hi all...
I want to integrate the AHU (Air Handling Unit), Fire System, Access Door, Lift (elevator) System, utility water pumping and distribution system, electrical power consupmtion monitoring system, Lighting system all in one integrated system (monitored via an MMI).

Click to expand...

Ade,

I think you have the wrong impression. Full control of all these different systems from one controller is not very realistic. All of these systems are very complex, & specialized for their spicific needs. However you should be able to monitor them all given the proper interfacing to one centeral HMI that would communicate with the individual system controllers.

i disagree with some of the post's..a B.A.S on a PLC would be far Superior than a "Anderson" or "Honeywell"...however it is no where near cost efective..A bunch of clients i know are turning away from Anderson, Honeywell and the like and going with open systems..Anderson "Has" to do the programming..same with Siemens and most of the major players..I just finished a system (ran the piping and wiring and terminated) for a BAS company..there software is open..If you don't like us then get someone else" is there motto..and ANYONE can program it..The controllers are off the shelf and available at any controls supplier..expansion is easy..It is by far becoming the choice of "big Building's" rather than be tied to Andover for 30 years..
To clarify on my PLC statement is better..I ran into a situation where the BAS took control of some cooling pumps, I explained to the tech what had to happen and he couldn't make it do it..It was a flip flop thing but intinstaniously..If the chillers detected a loss of pressure they would kick out..If both pumps kicked in it would blow the seals..his system had to much of a "scan time" to make the transition smooth..A PLC would do it less than 500Micro seconds but his took about 1 or 2 seconds..to much time!..As of now when i go hook up AC units i routinely come across Micrologix, Pico's and Moller relays in them..Plus if you take into account the down time with BAS a PLC wins hands down..However the initial cost is by far more than the BAS..

Again just my 2c

We currently operate a fairly large "Building Management" System.

It is ControlLogix based with about 700 local I/O count. About 350 "remote" I/O count and several controllers that handle the actual control of subsystems. The other controllers range from MicroLogix, FlexLogix, CLX,and SLC's, and some proprietery including the fire system and boilers.

We manage chiller systems, Air handlers, refrigerated storage, freezers, compressed air, Steam, Hot water, Distributed Vaccum system, Plant water supply, HVAC, Sewer system, VERY large NH3 compressor/condenser system.

You can access all these systems from several HMI's. The operators have no idea what controller is being accessed. It appears as one big system to them. In fact the HMI's talk to a bunch of different controllers. We do data collection for trending and record keeping. We also have web based reporting for management. It is a great system.

Maintenance gets a little more complicated with every new thing we add. Since it is mostly AB controllers we are able to keep it in house. We add screens to our HMI's and new controllers and I/O points routinely. Not every facility will staff someone that could maintain a system like this, but anyone with AB/Rockwell skills could do it. You still have choices.

I highly recomend using an "open" platform that gives the owner of the system options. "proprietery" sucks in my book. The brand is not important.

By the way our current system is a replacement for a proprietery system. It could not grow with our needs, so it had to go away.

Thanks every one for all of your comments/suggestions. I do really appreciate that.

From this moment on, I'm starting to learn more about it and still finding out what system is the best for my system based on your suggestion and comments.

Everyone have their own reason, for me, all of your reasons will be a good thing to start it out.

Thanks
-ade-

PLC is superior

RSL,

There is no doubt in my mind that ControlLogix can deliver a superior building management system. From what I know about Andover, CLX is way more powerfull and feature rich, with a superior programming platform.
Problem is that you need more expertise to program it and maintain it, you need more software packages to do the programming and it's
more expensive.
Building management systems also require frequent changes and additions as you have noted.
CLX has an inherent need for re-flashing and for re-surveying the
ControlNet with RSNetworx. This is the part I don't like.
It can be nerve wrecking at times.

I did not intend to pitch CLX as the only solution. It is in many ways overkill for most buildings. It can also be challenging for the first time user to get a handle on too. It is also VERY expensive. I do find that firmware upgrades these days to be more of an option than a neccesity. The product is finally maturing and stabalizing. I also think that the use of RSNetworx is blown way out of proportion. ControlNet is easy to schedule and VERY reliable.

In my first post, I meant to convey that any PLC or group of PLC's on a reliable network could easily handle building management. The PLC also rolls with the changes very easily. I would choose a PLC that supported as many communication protocols as possible. Regardless of the protocol I intended to use. This facilitates growth and future connectivity.

I prefer more than one PLC handling critical control locally. Possibly reporting to a supervisory PLC. By splitting duties up you end up not having the entire building crash if you lose a controller. An HMI can access each one directly also. If you have at least 2 HMI's then you are fairly redundant. You should have only isolated system failures or problems. I do not like all my eggs in one basket.

This can be accomplished with several products besides AB/Rockwell.

My opinion is formed from the absolute need for my system to be reliable. Outages are not considered acceptable in my plant at all. We pride ourselves on uninterupted service.

I am not all that familiar with dedicated building systems like Dover. I have seen several proprietery systems that were not very flexible at all. I really hate the thought of being at the mercy of the vendor or integrator.

RSL