Q: 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 […]

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Temperature 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 @ […]

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Time 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 […]

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Spring 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, […]

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The 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 […]

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Are 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 […]

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When 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. […]

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Actuator Sizing for Damper Applications

You have selected your damper by size and functional requirements, but now the question, “How much actuator do I need to obtain maximum close-off and to withstand the many cycles of operation?” This is a good question, and yet little information is published on this subject. Hopefully the following guidelines will aid you in your […]

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Not To Be Used As A Life Safety Device

Reprinted from Spring 2003 Insights Not to be used as a life safety device – This phrase appears on a number of Kele catalog pages as a warning to customers that the particular product (usually a gas detector) is not to be relied upon to safeguard humans or animals from a particular hazard.  It may, though, […]

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Hazardous Atmospheres: Intrinsic Safety

Reprinted from Summer 1999 Insights In the last edition of 20/20 Insights we covered the use of explosion proof construction to prevent a source of ignition from coming in contact with a room full of fuel and air. Strong enclosures with threaded or flanged covers can confine explosive forces within themselves and cool the escaping gases enough […]

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