Relay Testing Background Nearly all complex relays installed today are microprocessor-based. Relays no longer use a disk and magnetic fields to determine the overload condition, instead they rely on complex circuitry, programming, and user input settings to protect the facility. Each relay manufacturer utilizes different programming interfaces and languages and offers varying levels of customization. The various functions utilize an input (current, power, voltage, frequency) with or without a directional element to trigger a user-defined pick-up….
Data center owners want their new facilities to be completed on time, on budget, and operating as intended. This doesn’t seem like a particularly difficult task – except it is. Ask most people involved in data center construction, and they can give you tales of woe about projects gone wrong. All construction follows a similar path to completion: the owner identifies the need and budgets for a new facility, hires a design engineer, and awards…
The NEC requires over current protective devices (OCPD) to protect cables from overheating and catching fire which is achieved using long-time (LT) breaker settings. The NEC also provides guidance on ground fault (GF) and ground fault delay (GFD) settings. Additional settings on OCPDs include long-time delay (LTD), short-time (SD), short-time delay (STD), and instantaneous (I), which can be adjusted and coordinated to protect personnel and equipment from dangerous fault currents. If the only goal was…
Fitness centers are busy at the start of each new year as people renew their commitments to health and fitness with the help of sophisticated electronic equipment such as treadmills, exercise bikes, and stair climbers. One such facility contacted us desperate for help with repeated electrical problems, including variable frequency drive (VFD) failures, fitness equipment control screens locking up and requiring frequent reboots, and physical damage to electronic components requiring replacement. Building managers frequently blame…
Hood Patterson & Dewar (HP&D) is pleased to announce our status as a Certified Commissioning Firm (CCF). Organizations that hold the CCF designation stand out among competitors as experts – with the determination and ability to provide premier services to clients and the commitment to the advancement of the practice of commissioning. Established in 2002, the Building Commissioning Association (BCA) established the BCCB as a committee to oversee the process of creating a commissioning certification. Established in 1982, HP&D is…
Hilton Mills, HP&D grounding specialist, was presenting at a technical conference about best practices for testing substation grounding systems. During his presentation, he stated that after a ground grid is freshly installed, it will take some time for the voids in the soil to compress, providing a good connection between the ground grid conductors and the soil. Immediately after installation, these voids can cause higher than designed (calculated) impedance, touch, and step values, which should…
For the third consecutive year, Hood Patterson & Dewar is pleased to be in the top tier of the 25 firms recognized on the Consulting-Specifying Engineer’s 2021 Commissioning Giants list. HP&D reported a commissioning revenue of $27.2 million. The magazine’s report is based on the annual commissioning revenue of firms of all levels, including new or existing buildings, whole building, recommissioning, monitoring-based, fire protection systems, building enclosure (envelope), emergency power systems, retro-commissioning, and communications systems….
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