Ladder diagram for alarm panel
Ladder diagram for alarm panel
(OP)
I am just starting out in my on-hands electrical training and have been handed a challenge project. I am to layout a ladder diagram for an alarm panel for our plant. It will involve one central located panel which will be able to monitor nine different fault possibilities throughout the plant ie. low boiler water, low cooling sump levels, power failure etc. It is to indicate the fault with individual relays, lights and a buzzer. The buzzer to have a timer involved with a reset button to silence the alarm momentarily while resolving the cause for the alarm. I also believe having it set up with "fail safe" design would be an asset, as there would be an alarm should current flow be severed in any of the nine lines running throughout the plant. Any help out there would help solidify my new found interest, and be greatly appreciated.





RE: Ladder diagram for alarm panel
Sorry—no delicate way to put this—but from industrial-safety, regulatory and liability standpoints, a non-NRTL-labeled panel wouldn't be worth a plugged nickel.
RE: Ladder diagram for alarm panel
RE: Ladder diagram for alarm panel
What about adding some control to it?
Visit
http://www.cwtp.com.sg/DTSS%20Design%20Brief/Basis%20of%20Design/Section%2011.pdf
for more info.
RE: Ladder diagram for alarm panel
IMHO, your system is too small to consider using a PC or even a PLC. Although the hardware can be purchased cheaply enough, there is more to the picture than meets the eye. Sticking to relays can help you get familiar with the concept on a smaller system that is easier to understand.
Fail-safe in this instance means having the relays constantly energized and the alarm or trouble condition maintaining that circuit completion. This implies then that your field devices have Normally Closed (NC) contacts which may or may not be the case. Another potential pitfall is that when power is first applied, an alarm is sounded until all the relays pull in, something that can be problematic in and of itself. As simple as this appears, it may be better to record all of your conditions and exceptions, then take it to a professional.
Did you understand the meaning behind Busbar's response? NRTL stands for Nationally Recognized Testing Laboratory and refers to someone like UL or ETL. What he is refering to is that control and or monitoring systems such as this need to be built to certain standards in order to assure that they are not the causes of additional problems themselves. No offense intended, but it sounds as if you company has assigned an important task to someone who may not yet be ready to handle it, as evidenced by the fact that you are asking complete strangers protected by anonymity to assist you in designing it! If, heaven forbid, something goes wrong and catches fire, the insurance company investigator will look at this panel and determine that it was not built by someone with NRTL listing. He can then invalidate the claim entirely! Take your problem to a panel shop who can apply an NRTL label and allow yourself to sleep at night. They will have experience in the requirement and pitfalls involved in "simple" tasks such as this.
Subvert the dominant paradigm... Think first, then act!
RE: Ladder diagram for alarm panel
RE: Ladder diagram for alarm panel
You are in training....You are not designing an actual system for install and operation, correct? But your training is expected to help you later when you need to troubleshoot and repair such systems in your plant?
Great. Do like I first did when I got onboard my first of many nuclear submarines and thereafter when I started a new job at every place I went. Go dig out the prints for your install. Using those prints, trace out and locate every component. Take readings and measurements thru the system. Identify and research each component....Then draw it all out-making it work on paper.
Glad your plant insists on such training. Stick with it, and good luck! Come back here with your questions.
RE: Ladder diagram for alarm panel
RE: Ladder diagram for alarm panel
Sir,
With all due respect, you are in way over your head. Pray that your supervisor will catch your mistakes.
I worked for several years as a loss prevention inspector for Hartford Steam Boiler Insurance and Inspection Co. So your statement "Not a fire detection system, or burglary system which would definitely involve insurance concerns" is incorrect. If you have boiler/machinery coverage, your insurance Co. will demand any such install be properly coded and approved. Investigate if you have such coverage. If so, work with your boiler/machinery insurance provider on your planned install. They will assist you all the way. If you have either FM, HSB or Travelers ins, you can expect decent support from them....The rest only play the numbers game.
But yes, you are correct to desire it be 'fail safe', as they will insist on that too. Boilers and Ammonia refrigeration plants have the potential for tremendous losses and injuries. Once your deductable is satisfied, they make up for business loss and equipment repair/replacement up to the policy limits. So they are very careful when evaulating risks to limit their exposure and are quick to exclude any claim when safety devices or systems are not installed or maintained to code.
Good Luck
RE: Ladder diagram for alarm panel
RE: Ladder diagram for alarm panel
This involves learning that PLCs programming, but you can still learn ladder logic if you purchase a PLC with a ladder programming language.
Here are the reasons you want a PLC.
1 - Flexibility - Modify and improve the system with little or no re-wiring. Even if your first design works, you will inevitably come up with improvements at 2:00 am in the morning and want to make the improvement.
2 - Design Error Checking - If your original design fails you get to catch and repair it before wiring.
3 - Less expensive - You need not purchase some great big PLC system, you can order one today for $100.00 plus the software and cable for about $100.00. We call these small guys "relay replacers".
4 - No back feeds - Standard relay systems can have back feeds that require locating and correcting, PLC ladder programs do not have the problem.
5 - Reliability - At first we used to think that relay systems were more reliable than PLCs, but exactly the opposite is true. Relay systems have far more wire connections and devices like time delays that go bad.
6 - A PLC makes a truly refined system with features you cannot possibly get on a relay system: contact de-bouncing, short 1-5 second time delays to prevent nuisance alarms, plus greater flexibility of "components" such as counters, high speed counters, on delays, off delays, interval delays, alternators, etc., and almost unlimited amounts of them too.
Now is the time to "get your feet wet" with PLCs, not relays and time delays building a system un-refined and error prone.
Richard Neff
Richard Neff
Irrigation Craft
RE: Ladder diagram for alarm panel
ktmbruce
RE: Ladder diagram for alarm panel
RE: Ladder diagram for alarm panel
ktmbruce