Surveys Part II – Surge Protection

ALLTEC Protection Pyramid Surveys — A Three Part Series

If you missed Part I, you can read it here:  Part I — Grounding/Earthing, & Bonding.

Grounding/Earthing and Bonding alone are not sufficient to adequately protect a facility. The second tier of the Protection Pyramid diminishes the significance of random high-energy, short-duration electrical power transients through properly installed surge protective devices.

These occurrences are typically caused by atmospheric phenomena (such as lightning strikes), utility switching, inductive loads, and internally generated overvoltages. Transient voltage surge suppression (TVSS) or surge protection devices (SPD) should be incorporated and fully integrated into the facility’s inspection and maintenance program.

Studies have verified that approximately 80% of transient activity at a given facility is internally generated. For example, when a vacuum cleaner or heavy duty motor is powered on or off it creates an inductive load, which is a low magnitude surge impulse that propagates back through the electrical system. While internally generated transient activity can weaken equipment over time, the threat posed by lightning activity is particularly disconcerting due to its capability of delivering vast amounts of energy into unsuspecting electronic equipment loads.

As with any survey, the best way to start is with a site evaluation:

Electrical transients are momentary bursts of energy induced upon power, data, or communication lines. They are characterized by extremely high voltages that drive tremendous amounts of current into an electrical circuit for a few millionths, up to a few thousandths, of a second. Large transients on the power system originating outside of a facility are best initially diverted at the service entrance of a facility. Transients generated within the premises are best diverted by SPDs located close to the internal source of the transients or close to the electronic load equipment if this is not possible. Best results are obtained if both locations are protected.

Standards for the “Installation Requirements for Lightning Protection,” NFPA 780, Section 4.20, and UL 96A, Section 13 detail the requirements for surge protection associated with lightning protection systems. IEEE 1100 – 8.6 states: Surge activity is often assumed to be an outside engendered anomaly. Lightning-induced electrical energy bursts, for example, typically come to mind as the primary source of surge activity. However, while lightning induced surges represent the most formidable transient related equipment menace, most surges originate from internal sources within a facility.

After developing an understanding of the facility and its needs, a site-specific inspection plan is created. Typical actions include:

In order to determine the proper surge protection devices to be installed, the following information should be obtained, for reference during and after the survey:

Depending upon the complexity of the power distribution system, as well as the facility grounding system, it is quite often very efficient and effective to inspect and test both at the same time. Start at the main utility power entrance, the main distribution panel and follow the critical load paths. A typical example of a simple system and the proper location of surge protection devices is shown in the riser diagram below.

Drawing mark-ups, notes and photographs taken during the inspection are valuable in creating an inspection and recommendations report. During the inspection, field notes should be gathered and organized, recording:

On-Site Survey & Testing, Data Analysis and Computer Modeling should yield a Survey Report and supporting documentation containing observations, testing and data analysis, and site photographs as needed. Reports should include

One of the most important investments a company makes is in sensitive electronic equipment. As this equipment becomes more sophisticated and electrically susceptible, the need for a properly sized and coordinated surge protection becomes more crucial. Examples, such as cellular, radio and television broadcasting sites, computer facilities, power substations, communication centers, medical facilities and industrial plants all share the common need for the design, implementation and inspection/maintenance of high quality surge protection systems.