When it comes to selecting an electronic to pneumatic (E/P) transducer, the type of input and the pressure range of the output are the most common selection criteria considered. There are a couple of other specifications that are worth reviewing to select the best transducer for the job. These additional specifications are Air Consumption and Air Capacity. Read more
Tech Talk: Demand Control Ventilation
How many sensors are required in a typical installation? Where should they be located?
The number of zones with different occupancy patterns should dictate the number of sensors. In a small office application, for example, it would be ideal to have a sensor in the office space and one in the conference area. Carbon dioxide distribution in a space is influenced by the same factors that influence temperature distribution. These factors include convection, diffusion and mechanical air movement. Much like temperature sensors, placement of CO2 sensors should be based on the zone to be controlled and anticipated loads (e.g. common occupancy density and patterns). For optimum control, there should be a CO2 sensor placed in every location where temperatures controls are used. If an HVAC system is serving a series of zones with similar occupancy patterns, sensors placed in the return air ducting may be appropriate. Read more
A simple approach is the future of building automation systems
Thanks to improved wireless networking technology and standardized communication protocols, it’s easier than ever to collect data from sensors. Plus, silicon chips continue to get cheaper, faster and better and can be located in valves, actuators, thermostats and wall outlets to provide more memory and faster computing.
With the Internet of Things (IoT) continually expanding and easier access to cloud computing, it’s possible to transmit information, crunch numbers and use data like never before.
That means it’s time to take a fresh look at every element of a building — from small electrical switches, door locks and lights to massive chillers and boilers — as a way to gather and share information.
Most importantly, we need to re-examine the role of building automation systems (BAS) to enable the data and technology to merge and seamlessly solve problems in innovative ways, especially in smaller buildings.
Kele, Inc. Completes Acquisition of Control Consultants, Inc.
MEMPHIS, TN and BOSTON, MA – Kele, Inc. (Kele) announced today the acquisition of Control Consultants, Inc. (CCI). This strategic combination highlights each company’s long-term commitment to providing industry leading products and solutions to its customers. The combined entity will operate as separate brands, but will leverage the strengths each bring. Kele and CCI headquarters will remain in Memphis, Tenn. and Boston, respectively. Richard Campbell, current president and CEO of Kele, will serve as president and CEO of the combined company. Campbell has over 30 years of experience with commercial and industrial products, 27 of which were spent with Trane focused on heating, ventilation, and air conditioning (HVAC) and building automation systems (BAS). Read more
Tech Talk: High Output Voltage for Transformers
Q. My 75 VA 120:24 volt control transformer has a high output voltage. It reads as high as 28.3 volts with a 123 volt input. The load is only 8 VA on the transformer. Why is the output voltage so high?
A. A control transformer will have a higher output at a no-load or low load condition. A typical transformer with a 24 or 25 volt secondary rating will output 28 to 29 volts with no load. As the load increases, the output will lower to rated voltage at a full load. You need to either add load to the existing transformer or use a smaller VA transformer.
Staying Safe from High Voltage with Remote Current Sensor & Relay Combos
Problem
Here’s a scenario that may be familiar: the current of a high voltage load needs to be monitored with a current sensor, and the current sensor needs an integrated relay with 10A rated contacts. It seems easy, however when working with high voltage, some special equipment (and maybe even a licensed professional) is required. Fair enough, a professional is called to the scene to install the current sensor and relay combination. Everything is going well until it is discovered that the trip point on the current sensor is too high, and something needs to be adjusted! There’s no option but to get the licensed professional back out to the scene to make the small adjustment. This installation is taking a lot of time, and time means money. Read more
Building Automation and The Internet of Things
The Internet of Things (IoT) is changing the way people run their homes. More and more devices are becoming available to consumers that allow them to automate their thermostats and regulate their power consumption, often-times controlling these systems from the phone in their pocket. Products like the Nest thermostat and the Sense home energy monitor provide homeowners convenient tools that also help save utility costs. Read more
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 supply transformer winding, a mechanical failure in switching equipment, or when a single fuse blows. A 3-phase motor started in a phase loss condition may stall under load. The current flowing in the windings of a stalled motor will increase to the motor locked rotor current which is around 600% greater than the motor’s normal full load current. Motor winding insulation subjected to locked rotor current may fail in as little as 15 to 90 seconds. Read more
What You Need to Know About the Solar Eclipse
Are you excited about the solar eclipse? Us too! Today, August 21, 2017, the moon will completely cover the sun and the sun’s atmosphere, thus creating a “blackout.” The celestial event will be the first in decades since the last total eclipse took place in the United States, and the first in over a century to have a path of totality span most of the country. Kele cares about your well-being. Please remember to protect your vision while viewing the eclipse by wearing ISO-compliant solar glasses. Your vision may be impaired during the eclipse, so take extra caution! You don’t want to go blind! Read more
Tech Talk: DC Power Supply and Class 2 Labels
Q. The Inspector says my DC power supply needs a Class 2 label. What’s he talking about?
The Inspector is referring to the requirements of Class 2 circuits and wiring as defined in the National Electric Code (NEC). The definition of Class 2 circuits specifies the wiring system between the load side of a Class 2 power source and the connected equipment. The definition includes current and voltage limitations [NEC Table 11(A) and Table 11(B)] to limit the possibility of fire initiation and electric shock. Class 2 circuits offer reduced requirements for wire size, wire insulation, over-current protection, wiring methods and installation materials and can be advantageous in reducing cost and improving flexibility of an installation. Also, many local municipalities now require that the NEC Class 2 standard be maintained in public buildings, schools and hospitals. Read more
