Three transformers serve electrical loads for an office building, data center and mechanical equipment

BY TAREK G. TOUSSON, PE, STANLEY CONSULTANTS, AUSTIN, TEXAS NOVEMBER 11, 2019

The design of an electrical distribution system for a confidential client was required for office building loads, data center loads and supporting mechanical equipment loads. The new electrical distribution system design involved coordination with the electrical utility company to replace utility transformers.

Transformers are an essential component of almost any electrical distribution system. Design engineers should know the design concepts, the codes and standards for selecting and sizing transformers to ensure they are appropriate for the application

BY TAREK G. TOUSSON, PE, STANLEY CONSULTANTS, AUSTIN, TEXAS NOVEMBER 11, 2019

#Critical Power: Generators and System Design
This generator and generator system design course will go over the critical details and best practices to consider when commissioning and designing generator systems for various building types and applications.

The learning objectives for this course are:

• Understand the applicable code requirements including NFPA 70: National Electrical Code and NFPA 110: Standard for Emergency and Standby Power Systems
• Learn the criteria for selecting the appropriate generator or generators for the building type and/or application
• Understand the criteria for designing the generator system, and know the differences between prime rated versus standby rated engines (U.S. EPA standards)
• Learn the criteria for commissioning generators and the electrical systems they support.

Critical Power: Hospital Electrical Systems

Power loss for a hospital could be devastating. In the event of a utility outage, patients' lives are at risk, and maintaining power and communication systems through emergency power-generation systems is critical.

The learning objectives for this course are:

• Explain the applicable codes and standards: NFPA 70 National Electrical Code, Article 517; NFPA 99: Health Care Facilities Code; NFPA 110: Standard for Emergency and Standby Power Systems; and various hospital accrediting agencies.
• Assess the unique electrical system requirements of hospitals including those for patient care and nonpatient areas.
• Analyze and compare the differences between emergency and essential power, connected load and demand load, the branches of the emergency power supply system (EPSS), and the types of equipment associated with each branch.
• Outline backup, standby, and emergency power systems for hospitals versus other building types.
• Highlight recommended best practices such as ASHE Handbook for Electrical Systems and IEEE White Book.

#Electrical Systems: Designing Electrical Rooms
In this course, registrants will learn about the criteria involved with designing electrical rooms, requirements for electrical rooms, and best practices to consider during the design process. Each section throughout the course will guide you to designing an electrical room that is safe and secure, and functions properly.

#Learning objectives for this course are:

• Understand the applicable code requirements including NFPA 70: National Electrical Code.
• Learn the design criteria for appropriate electrical room size to accommodate present and future needs.
• Understand the requirements for coordinating with structural, architectural, fire protection, and HVAC requirements.
• Understand the requirements for foreign systems such as ductwork and piping.

I told the telephone repairman, “It seems like we never had trouble when we had copper pairs; but now since you guys went to fiber, we are having lightning damage to anything connected to the fiber.”

Well, the guy was on the ball. He said, “You know, the fiber is in a copper shield to protect it from crushing; maybe it’s coming in on the copper shield.”

The shield was bonded to the modem, which had the usual four-foot ground rod driven. Next day, they sent a crew that terminated the copper shielded cable outside and ran just a piece of fiber, one strand into the house and moved their modem to the basement.

Now there is a length of 15 feet of pure glass between the incoming cable and the modem. Since that was done two years ago, we have had no trouble, though the storms are as potent as ever.

The Chairman of the Liberia Electricity Regulatory Commission (LERC), J. Aloysius Tarlue, Jr. says the commission is committed to fostering an effective regulatory climate that will be result oriented in giving a new lease of life to the underperforming electricity sector.

By this pronouncement, member of the public are expecting a new direction in the implementation of the 2015 Electricity Law of Liberia.

The area of emphasis under the new order of transformative leadership that Chairman Tarlue has promised, “the right regulatory scheme will be set up to win investors’ confidence whilst addressing consumers concern”.

Speaking recently at a local hotel in Monrovia with stakeholders in attendance to review a draft regulatory instruments and procedures Chairman Tarlue reassured that the merger of best practice approaches to include competitive electricity market, private capital and enlightened regulation, would ensure remarkable progress in power generation and distribution. //

Several presentations were made on the draft Electricity Licensing Regulations, Micro Utility Licensing Regulations, draft Electricity Licensing Handbook, Draft Administrative Procedures Regulations. All suggestions and inputs made will be incorporated into the new regulations, it was revealed.

“Thermal expansion is another important issue. The thermal expansion of aluminum is much larger than copper’s from normal ambient temperatures down to –20°F. That’s important because substation transformers are built to a specific design coil height, and coil windings are clamped to keep that height fixed. As our load fluctuates, transformer temperatures rise and fall. The coil wants to compress and expand, but it can’t because it’s clamped. Instead, it compresses the paper insulation between turns (Figure 3). The effect is especially pronounced when a fault occurs, but it affects aluminum windings much more so than it does copper due to the difference in thermal expansion.

“Later, when the temperature returns to normal, the insulation in an aluminum transformer might not be as tight as it was before the overload. That allows the windings to loosen slightly, a condition that might lead to loose connections at some point in time.”

Leighty believes copper also helps reduce lifetime ownership costs. “Again,” he says, “it’s due to copper’s higher strength. Life-cycle cost is not just a matter of efficiency (even though that’s important), it’s also a function of reliability.

“For example, we expect a 40- to 50-year life cycle in our transformers. We monitor their condition with periodic oil analyses. When an analysis shows that gas and moisture are increasing, it’s a sign that the oil is breaking down and that there’s probably overheating going on at a connection inside the transformer. If you have aluminum-wound coils, the internal connections can loosen (creep) over time, just like connections in aluminum house wiring did 30 years ago. Loose connections cause the heating that breaks down the oil. We almost always identify the problem before it gets out of hand, but, when we don’t, the result can be catastrophic.

This webinar will review the elements of a building’s wiring and grounding systems (including lightning protection) that pertain to power quality at communications facilities and improve up-time. Proper wiring and grounding, beyond those minimal requirements of the NEC, can greatly alleviate power quality problems in broadcast and public service communications facilities. These improvements can be very cost-effective, usually simple in description, and help prevent costly downtime and equipment damage. The presentation concentrates on actual experiences at broadcast facilities where grounding and lightning protection were of paramount importance in maintaining system availability.

About Your Instructor - David Brender, P.E., National Program Manager Copper Development Association, Inc.

David Brender is National Program Manager for the Copper Development Association (CDA) in New York City. His duties involve directing and managing the electrical programs at CDA, including their power quality, building wire program, telecommunications wire, research and National Electrical Code activities, among others. He has presented several times before to broadcasting technical audiences.He is a principal member of Panel 5 of the National Electrical Code, a Senior Member of the IEEE, and a life member of the Association of Energy Engineers.

Brender holds a Bachelor’s degree from New York University and an MBA degree from Fairleigh Dickinson University in addition to being a licensed Professional Engineer in three states.

250.52(A) Electrodes Permitted for Grounding

The rule explaining when a structural metal frame can serve as a grounding electrode has been changed again, and the requirements for concrete encased electrodes, ground rods, and ground plates have been clarified.

(3) Concrete-Encased Electrode. At least 20 ft of either (1) or (2):

(1) One or more of bare, zinc-galvanized, or otherwise electrically conductive steel reinforcing bars of not less than ½ in. diameter, mechanically connected together by steel tie wires, welding, or other effective means, to create a 20 ft or greater length.

(2) Bare copper conductor not smaller than 4 AWG.

The reinforcing bars or bare copper conductor must be encased by at least 2 in. of concrete located horizontally near the bottom of a concrete footing or vertically within a concrete foundation that’s in direct contact with the earth.

If multiple concrete-encased electrodes are present at a building/structure, only one is required to serve as a grounding electrode

Note: Concrete containing insulation, vapor barriers, films or similar items separating it from the earth isn’t considered to be in “direct contact” with the earth.

(4) Ground Ring Electrode. A ground ring consisting of at least 20 ft of bare copper conductor not smaller than 2 AWG buried in the earth encircling a building/structure can serve as a grounding electrode.

IDAHO FALLS — New nuclear reactor technology is being developed here in Idaho, and Idaho Falls Power wants a piece of it. NuScale Power is developing a new kind of nuclear reactor they believe will be safer, smaller and cheaper than current reactors. Idaho Falls Power is hoping to take advantage of the new reactors …

Seasoned travellers are well aware of the many different plugs and sockets in use around the world. 

But which plug is used where?

First-time travellers to foreign countries may only find out when confronted with the problem of trying to plug their razor or hair-dryer into a socket with an unsuitable configuration, like pounding a square peg into a round hole.

With this problem in mind, the IEC created a plug and socket zone that is both informative and practical. It explains why things are as they are today and how they might be improved. It also provides information on the plugs, sockets and voltage used around the world, along with illustrations of the various plugs and sockets available.

Locating a panelboard directly beneath the drain or other piping systems is a violation of Sec. 110.26(E). For indoor installations, Sec. 110.26(E)(1)(a) requires the space directly above the panelboard to be kept clear of piping or other foreign systems for a height of 6 ft or to the structural ceiling, whichever is lower. This “dedicated space” zone also extends down to the floor. This “dedicated space” is for the electrical equipment only. Except for suspended ceiling systems, other piping, ductwork, leak protection equipment or equipment foreign to the electrical system may be placed in this zone. The space above the 6-ft height is permitted to contain foreign systems, but protection must be provided to avoid damage to the electrical equipment from any leaks or breaks in those foreign systems. The drainpipe in this photo is only 2 ft above the panelboard and there is no leak protection provided.

The National Electrical Code (NEC) requires a given conductor to be a minimum size for a given load under specific conditions of use. The reason for this is to protect the conductor insulation from overheating. So, to understand conductor sizing, you need to understand a little about conductor insulation.

Everyone makes mistakes — some are just funnier than others. That’s truly the case in “Short Circuits,” a fun department and fan favorite that ran for several years in the print magazine in which readers sent in their most memorable job-site blunders. This conglomeration of electrical goofs was in no way meant to minimize the importance of taking electrical safety seriously because we all know that mistakes in the electrical industry can be deadly. However, these botched electrical installations were light-hearted in nature, did not ever result in serious injury, and served as a way for readers to share the hilarious situations that sometimes crop up in the field while remembering valuable lessons.

Having just woken up from one of my utter-lack-of-power naps I reviewed several threads and notice an odd coincidence: every one of them mentioned some inappropriate use of one component or another, and often with not-at-all hilarious consequences.

From switching out breakers to picking the wrong batteries to expecting AC controls to handle DC it's all been done, and never are the results what the user intended.

So go ahead guys: tell us your tales of "You won't believe what they were using for this!"

Conduit fill tables for electrical wire

It seems to be the lost art. None of the contractors, architects and very few of the engineers I've had contact with have ever heard of it... a cheap earthing system that consistently outperforms typical ground rod installations. This is a proven concept, but before I describe it, let me make it clear that I take no credit for its design.

During World War II, a retired Vice President of Underwriters Laboratories, Herbert G. Ufer, developed it for the U.S. Army. Igloo shaped bomb storage vaults were being built, and possible static and lightning induced detonation problems were of concern. Ground conductivity was poor, and to be effective enough, ground rods would have to be driven several hundred feet. After much research and testing Mr. Ufer advised the Army to make connection to the steel bar that would internally reinforce the concrete foundation. He had determined that concrete was more conductive than all but the best soil, and that this improved semiconducting characteristic would enhance surface area contact with the surrounding soil. The wire ties normally used would be extra secure, and attention would be given to bonding or welding the lattice- type network together. The Army adopted the idea, and built the vaults as

specified. After construction ground resistance tests were made. No measurement exceeded five ohms. This value was considered extremely low for the local soil conductivity. Later tests confirmed stability. Mr. Ufer went on to develop the concept of concrete encased grounding electrodes. Many of his findings are detailed in IEEE Transactions paper # 63-1505. His system has since been used by the military, utility companies, Lake Tahoe lifts, and industry throughout the country. Why not broadcast stations? After reading an obscure 1967 paper citing actual tests and comparisons to conventional systems written by Wismer & Becker Engineers, I decided to give it a try.

Low resistance earth grounding is essential for safety and protection of sensitive electronic equipment. It is the basis for any facility's power quality assurance program.

This paper presents the advantages of deep driven electrodes over shallow (10 foot or less) electrodes. This paper will demonstrate that deep driven electrodes provide low earth resistance, are economical to install, maintain low resistance over time, are maintenance free, and do not have environmental concerns. This paper utilizes field data taken from over 140 deep driven electrodes installed over a 5 year period in several states. A discussion includes the development of the equipment, materials, and process used to install and test deep driven made electrodes. The process includes a new technique of injecting bentonite into the coupler void to maintain full rod contact of the total length. Several site reports are presented and discussed. This paper would be of value to anyone responsible for specifying, installing, or testing low resistance ground systems.