Since starting my apprenticeship back in July, I have learned that there are many facets to electrical work that I had never previously thought about, or if I did, never associated with electrical work. Since October, I have been on a project doing "control work". When I was first sent to my current site, I had no idea what control work entailed. What I have discovered is a fascinating and unexpected corner of the trade that, quite frankly, I had never known to exist.
Before entering the trade, I was familiar with the panels in the utility rooms marked "Siemens". I had noticed them....but never really given a great deal of thought as to what they did and what purpose they served. Now I understand that these simple looking panel enclosures house the brains of many complex functions. They can control everything from water flow to air pressure to ambient temperature in a space. Without these nerve centers, the apparently seamless operation of many commercial spaces would not be possible. The devices that regulate these operations would be useless without a control module or a Siemens module to tell them what to do.
We started by pulling our control wire. Seemed simple enough. Next, we learned to terminate the devices. Learning the different devices and their function was interesting, but nothing earth-shattering. Then I was given the opportunity to begin learning about panel termination. WHOAH!
This is where it all came together. First, we had to build the panel with the appropriate modules required by the panel schedule. Now things started getting deep. Learning how the modules take the information and interact with each other to send out commands, take status reports, change variables, and make everything flow together was the "light bulb" moment. Now we could begin actual termination. That's when things really got wild. The different cables carried different types of signals. So now, you had to be sure that the cable carrying the status to from the valve or thermostat or damper to the module was correct and different from the wire that would be carrying the command from the module to the device. The complexity of the systems cannot be understated (or necessarily adequately described in a simple blog).
The control systems remind me of the nervous system in the human body. The movement of impulses through the cables to and from the panel made me think of nerve impulses to and from the brain. The devices that receive the commands and, in turn, send statuses, are like arms and legs that move to a command or send "feeling" back to the brain. So, for example, if the Siemens panel module reads or "feels" from a device that the air pressure is too high or too low, it will send a command to the corresponding damper to open or close as needed to correct the problem. It's kind of like a hand getting too hot and the brain telling it to pull away before it gets burned!
I feel truly fortunate that the journeymen and foreman that I work with have so much experience in this specialty and are so generously willing to take the time to explain the operations of the different devices and modules to me and the other apprentices on our site. I am grateful to be able to benefit from their experience and patience and look forward to learning more about this exciting part of our trade!