Relay Fundamentals

Open an HVAC control panel, and you’re likely to find at least one relay mounted inside. Sometimes you find lots of relays! Even though relay technology has been around since the 1800s, there is still a need for relays in control panels. What components make up a relay? How are relays typically shown in wiring […]

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“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 […]

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Connecting A Voltage-Output Signal Source To Multiple Loads

The Tech Support crew here at Kele frequently gets quizzed by customers who have a voltage-output signal source which must drive multiple voltage-input loads. Requests for “voltage signal replicators” come in frequently. Sometimes extra hardware is needed, but sometimes it isn’t! So we thought it might be a good idea to write an article addressing […]

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THE (RS-485 Network) TERMINATOR Or The Dance of the Data Pulses

If you’re involved with building automation systems you know (unless you’ve been living under a rock like the guy in that insurance commercial) that the modern trend is to connect all your building controls together on networks. Networks make it easy to add or move control nodes as your building control needs change since the […]

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What is next, endicator?

In my last blog entry I raved about the endicator power monitor and how it will make my life easier and that is all true.  What the designers have done, unbeknownst to them, is they have made life easier for future DR too.  I’ll try to explain. Chances are if you are reading this you […]

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Making Your Job Easier (and Mine too)

My first exposure to power monitoring was the WT series. I started out in the warehouse shipping them. Then I progressed to stripping the wires used for the CT shorting assembly. After that I assembled them, put them in enclosures, and added the shorting switches when they were ordered. From the warehouse I moved to […]

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Need Help Retrofitting Pneumatics to Electric Actuators?

In the current economic times it can be difficult to convince a client that it is necessary to remove a working valve just to change out the pneumatic actuator controlling it.  Re-piping and draining the system alone means down time and extra labor that probably isn’t in the budget.  The obvious solution is to leave […]

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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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