Commissioning and maintenance procedures for low-voltage circuit breakers may include testing to determine whether the circuit breaker is able to respond correctly to faults or overload conditions as specified in the coordination study. This requirement may include ground fault (GF) as part of the protection scheme. Testing may be performed through primary or secondary injection; primary injection is the best …
There is always room for improvement. In electrical testing, this is particularly true because of the rapid development and application of the underlying electronics. Although a job may be proceeding with maximum satisfaction, it may well be made easier, faster, more accurate, and safer. For example, standby battery banks can develop ground faults over time through leaking electrolytes, accumulation of …
Locating faults in buried or concealed cable is one of the most demanding, inventive, and interesting chores in all of electrical maintenance. The operator’s skills, knowledge, and ingenuity are paramount. When the power goes out, an entire facility, neighborhood, or community can be abruptly shut down without warning. Normally, this goes largely unnoticed as the utility seamlessly switches to another …
As part of the electrification of a facility, it is commonly thought that merely connecting the system to a driven ground rod means that the building is grounded. It’s not that simple. By pure luck, such an approach may indeed work. But the considerable value of the building, the efficiency of operation, the wealth of information and knowledge that is …
“What’s in a name?” asked Shakespeare. The quote is so widely known because it’s so widely applicable. In the electrical industry, the terms “grounded” and “ungrounded” are commonly applied to electrical systems. They are often taken for granted or misunderstood. How can a grounding electrode be present, and yet the system is termed “ungrounded?” It is beneficial and productive to …
Electric vehicles are prominently heralded as the trend of the future, a vital part of many planned economies’ efforts to combat global warming, widespread pollution, and the squandering of resources. But there has also been negative publicity over safety issues like car fires. The key to enjoying the best of both worlds — excellent performance under complete safety — is …
Solar farms, which are exposed to the elements, are especially at risk for failure and require dedicated electrical maintenance. Good grounding is essential, as the panels produce high DC voltages that can be sources of shock and fire, as well as induced voltages and electromagnetic interference on lines. With respect to grounding, there are two types of photovoltaic (PV) systems: …
In an actual reported case, a severe storm blew down a large tree that struck a residence. A meter that should have been reporting 240 V reported a phase-phase voltage of 124 V. The falling tree had pulled down the service, which had then been re-attached by a service crew. A routine voltmeter check revealed 118 V between the left hot leg and neutral, …
The rapidly developing industry of renewable power generation can be compared to an hourglass. Inexhaustible supplies of free resources — sun and wind — are converted into a corresponding outflow of electrical energy at notable return on investment. But the process includes the neck of the hourglass through which the resources must pass. This is the solar array or wind …
Ground testing is often thought of as ground electrode testing: the measurement of the resistance associated with a particular rod or grounding system. A useful corollary to this is soil resistivity testing. Resistivity is the electrical property of soil itself that determines how well it can carry current. It varies enormously (Table 1) depending on physical and chemical composition, moisture, …