If you live in the world of HVAC design/installation, sooner or later you’re going to need to take measurements on a circuit using a voltmeter (even if it’s “not your job,” we all know how that goes). So we thought it would be a good idea to put together some basic instructions on using a […]
Read PostCategory: Back to Basics
“Currently” Playing: Connecting A 4-20 mA Constant-Current Signal To Multiple Loads
One of the most popular and long-lived methods for transmitting analog control signals in the HVAC and industrial control worlds is the “constant-current signal loop.” In this scheme, the value of the current flowing in the circuit is the control variable, rather than any voltages that may appear at different points in the circuit. The […]
Read PostNetworking 101: BAS Network Cabling
The various devices comprising a building automation network are either connected by cables or talk wirelessly to each other, or possibly a combination of both. In Networking 101, we are going to concentrate on network devices connected by cables. Let’s take a look at the different types of network cables typically encountered in building automation […]
Read PostQ: The intrinsic safety spec I’m reading calls for an isolated ground. Isolated from what?
Answer: A true isolated ground is not connected to any ground that can ever carry fault current from unrelated parts of the electrical system. It is best to run it directly to grounded building structural steel, an underground metal water pipe, or a separate grounding electrode from the building electrical service as described in Article […]
Read PostTemperature Sensor Curve ID Numbers
Need help figuring out what type sensor you need for your automation system? This handy temperature curve chart might help. If not, give Kele a call! Sensor Type Temperature Sensor Description Typical Sensor User 3 10,000Ω @ 77°F, Type III material AET, American Automatrix, Andover, Carrier, Delta, Invensys, Teletrol, York 21 2252Ω @ […]
Read PostTime Delay Relay Functions Explained
Understanding the differences between various time delay relay operations such as On-Delay or Interval can be a bit confusing. These simple diagrams may make it easier to visualize what’s happening during the timer operation(s). At Kele, our goal is to make product selection and usage as easy as […]
Read PostSpring Return Fail Safe Electric Motors
Consideration must be taken when designing a control system as to what happens when controllers fail or if there is a loss of power. This is referred to as fail-safe or spring return. Devices, like valves and dampers, can be made to fail in a position that provides a minimum amount of comfort control or, […]
Read PostThe Award goes to… Ohm’s Law!
If there were an awards show for Building Automation and Energy Management; there would have to be a lifetime achievement award. All awards shows have them. For Building Automation and Energy Management there may be none more deserving than Ohm’s Law. Ohm’s law may be the Beatles of Building Automation and Energy Management. The influence […]
Read PostAre You Sure You’ve Checked Everything?
Late one afternoon not long ago, a fellow got me on the phone for tech support. He said he had ten carbon dioxide transmitters on one DCP-1.5-W power supply, and they weren’t operating, and he had pulled out most of his hair. Each transmitter needs less than 100 mA to operate, so the 1.5A power […]
Read PostWhen Electricity Acts Up
This past weekend, we were just back from a trip to market, and my wife was busy stowing the fruits, veggies, oils, kimchi, and spices. I was doing my usual chore of qualifying and sorting the plastic shopping bags as to fitness for cat litter duty, kitchen waste duty, and “other,” based on leakage potential. […]
Read Post
