Category: Back to Basics
Panels 101: Designing and Building Control Panels
The most critical element that shapes a panel design project must be addressed at the very beginning of a project: where is the completed unit going to be installed? This very basic question dictates the type of protection the enclosure must provide to the equipment. The switchgear inside the enclosure must be protected from the […]
Read PostTech Talk: I need an explosion-proof control panel with a few pilot lights and…
Q: I’ve been buying explosion-proof enclosures and devices from Kele, and I must say that the Hazardous Locations section of your catalog is a gold mine of hard-to-find products! Now I need an explosion-proof control panel with a few pilot lights and externally operable selector switches mounted on the door of the panel. Can Kele help me with […]
Read PostTech Talk: Timing relays are confusing to me. Can you explain the difference between single-shot and interval timers? What happens if the output driving the relay changes state during a timing sequence?
When all of the possible combinations of timing states and initiating device transitions are considered, a stronger word than “confusing” may be in order! Below are some timing diagrams and sequences of operation in simple terms that may be of help. Since it is an electronic circuit that is energized rather than a coil, the […]
Read PostTech Talk: do you have a product that provides manual override if the controller does not support override capability?
Tech Talk: 3-Phase Motor with One Lost Phase
Q: What happens to a 3-phase motor when one of the phases is lost? The most extreme case of phase unbalance is the total loss of one of the three phases and is known as phase loss or single phasing. Phase loss can be caused by a broken power line, a lightning strike, an open […]
Read PostRelay 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 […]
Read PostUsing a Multimeter Series – Resistance Measuring Basics
“Resistance is futile, Buwhahaha” exclaimed the villain, rubbing his hands together in glee as our hero struggled to free himself from the ropes that bound him. Yep, we’ve all seen those Grade B movies. Maybe in that situation resistance is futile, but in the world of electronics and HVAC controls resistance (electrical resistance) is very […]
Read PostUsing a Multimeter Series – Voltmeter Basics
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 Post“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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