One MCM is equivalent to 1000 circular mils. For comparison, 1 MCM equates to 0.5067 square mm, so for many purposes , a ratio of 2MCM to 1mmsq can be used with a 1.3% (very small) error.

Meredith Angwin @MeredithAngwin
·
Dec 23
Grid frequency drifting outside operational limits implies the system is running at the margins. https://watt-logic.com/2024/12/23/gb-grid-frequency/
Thanks to Kathryn Porter for this analysis!
From watt-logic.com

chrispydog @chrispydog
When I explain this stuff to people: "Have you seen when a spinning top starts to wobble, and what comes next?"

Most people 'get it' pretty fast.
4:34 PM · Dec 24, 2024. //

I then analysed the number of 15-second intervals in each winter season for which the operation or statutory limits were breached. The results are in the table below. As can be seen, in the past 4 years, there have been c 500 times the upper operational limit was breached, but in 2017 – 2019 the number was higher. The lower limit has tended to be breached less often – 2022 was an outlier with a very high number of breaches. There has also been a consistent trend of lower limit breaches increasing in frequency, which is consistent with falling grid inertia (see chart). //

This fits with the expected picture that the grid is becoming less reliable. It is also interesting that when individual occurrences are inspected, it is more often the case that frequency has drifted outside the operational range rather than suddenly falling out as would be expected from an outage. This is more worrying as it points to a general difficulty in maintaining stable frequency – things will always break and trip, and the grid is designed to deal with that, but these drifts outside the range speak more to a wider reduction in stability versus what is expected.

In a June webcast, "System Design Tips and Tricks for Switchgear and Switchboards,” expert presenters discussed switchgear and switchboards in more detail. Additional questions are answered here by Sean Hu and Andria Odrowski.

Most properties today, whether residential, commercial, or industrial, include at least one building or structure on that property. Often there are multiple buildings on a single property. Some include buildings that are each supplied by its own utility service and others have an electrical service at one point and deliver electrical power to the other buildings or structures by feeder(s) or by branch circuit(s). This article takes a closer look at the grounding and bonding requirements and methods for separate buildings or structures supplied from other than a service. //

The second method for grounding and bonding at a separate building or structure is allowed where the feeder does not provide an equipment grounding conductor, but does include a system grounded (often a neutral) conductor. This second method is a bit more difficult to utilize because there are more specific restrictions that must be considered and adhered to. Three conditions must exist before one may use the grounded conductor for grounding purposes at a separate building or structure.

Figure 4. Grounding and bonding at separate buildings or structures using the grounded conductor by the method specified in Section 250.32(B)(2)

The first condition is that an equipment grounding conductor, of any form specified in 250.118, is not provided or run with the supply to the structure. This means that only the phase conductor(s) and the system grounded conductor either as direct burial, in nonmetallic conduit underground, or as overhead conductors are included. The key is that no equipment grounding conductor is included.

The second condition is that no continuous metallic paths exist or are otherwise present, and that are bonded to the grounding system in both buildings. Examples of continuous metallic paths could be metal water piping, building steel, metallic conduit, cable shields, metal ducts, and so forth.

The last condition that must be met prior to utilizing this method is that no equipment ground-fault protection is installed on the supply service or feeder, as neutral-to-ground connections on the load side of this equipment can nullify or desensitize the equipment protection.

If all of these conditions are met, then the grounded conductor of the feeder or branch circuit is permitted to be used for grounding and bonding the electrical equipment. It must be connected to the structure disconnecting means enclosure to which the required grounding electrode conductor is also connected. The minimum size of the grounded conductor of the feeder or branch– circuit must satisfy two minimum sizing requirements. First, it must be adequate to carry the maximum load on the grounded (often a neutral) conductor as specified in 220.22. Second, it also must not be smaller than the required equipment grounding conductor for the feeder or branch circuit using 250.122, based on the size of fuse or circuit breaker ahead of it.

How do I Select the Right Inrush Current Limiter for My Application?

Inrush current limiters are designed with different characteristics like resistance versus temperature curve to accommodate numerous applications. Because of this, it is necessary to make some calculations based on your system requirements to select the best inrush current limiter for your needs.

Large transformers have a huge current demand when they are initially turned on. This is because, until the magnetic field and inductive resistance builds, they are essentially short circuits. For example, you may have turned on some large tool or appliance and heard an initial large "HUMMMMMMM". That is the transformer say "Ow". The circuit breaker for that outlet might also go "Whoa, what are you doing!"

The transformer above (Avel Y236907 800VA 45V+45V Toroidal Transformer), for example, will try to draw over 100 Amps on the first cycle of 60 Hz Power.

To keep a large transformer from being damaged at turn-on (and to keep it from saying "ow"), or to keep a breaker from popping, you put in an inrush current limiter circuit. This Instructable will detail how to do that.

Electrical engineers must learn to navigate industry codes and standards while designing battery energy storage systems (BESS)

The Coordinaide protection and coordination assistant software lets you quickly and easily select the optimal protective device (e.g., fuses, VacuFuse® II Self-Resetting Interrupters, TripSaver II Cutout-Mounted Reclosers, Vista® Underground Distribution Switchgear, or IntelliRupter® PulseCloser® Fault Interrupters) to:

• Protect transformers against damaging overcurrents and coordinate with primary- and secondary-side protective devices.  See how S&C's novel Transformer Protection Index (TPI) can be used to determine if the primary fuse will protect against certain types of secondary-side faults, including arcing phase-to-ground secondary-side faults.
• Protect capacitor units against case rupture.
  Protect underground cables from insulation damage due to excessive temperatures.
• Protect overhead conductors from damage due to annealing.
• Confirm the proper operation of protective devices against incident-arc energy curves for various Personal Protective Equipment (PPE) levels.
• Selectively coordinate two or more devices in series to minimize service interruptions.

PowerOutage.us is an ongoing project created to track, record, and aggregate power outages across the United States.
Find out about us on our About page.
Click on a state to see more detailed info.
Data is updated site wide approximately every ten minutes.

Combining a reliable and customizable design with a remote-control display screen featuring a LED bar, the Eaton Ferrups FX UPS provides rugged, IIoT-ready protection for your industrial power infrastructure. The Ferrups FX UPS supports extended runtime applications and can be deployed in harsh power environments where traditional uninterruptible power supply models are susceptible to power surge events. This industrial UPS is a completely updated and revitalized edition that builds upon the decades of proven performance of the legacy Eaton FERRUPS UPS.

Formerly Powerware FERRUPS Tower UPS

The EATON FERRUPS new FX Model delivers proven, ferroresonant battery backup power and scalable runtimes for 911 centers, global military installations, marine vessels and other critical applications. Highly configurable with a wide range of voltages, frequencies, runtimes, power cords and receptacles, the Eaton FERRUPS continually regulates voltage and eliminates harmful harmonic currents.

Calculates the short circuit fault current level of a 3-phase, core type transformer with a Dyn winding connection.

These handy electrical formulas and electronics formulas (AC Ohm's law formulas on front, DC Ohm's law formulas on back) also give you very useful formulas for apparent power, 3-phase apparent power, power factor, reactance, motor sync. generator frequency, 3-phase WYE, 3-phase delta, sine wave values and more!

As you can see on the Ohm's law charts, there's a wide variety of colors encircling the diagram. These colors serve a purpose. You can easily identify resistor band colors by looking at the chart. For instance the color brown in the 1:00 position represents the value of one...and so forth, up to the silver in the 10 minutes to position which represents 10% tolerance - the gold in the 5 minutes to position represents 5% tolerance.

In accordance with the 2015 Electricity Law of Liberia (ELL), LERC is empowered under Section 3.3 to issue Regulations designed to implement the law. Therefore, the Commission prescribed these Regulations:

Electricity Licensing Handbook.pdf - 1166kb

The Electricity Sector of Liberia has been characterized by monopoly of generation, transmission, and distribution services, and there has also been a fusion of roles, where policy, regulation and operation were combined.

Regulatory functions of the energy sector were relegated to the Ministry of Lands, Mines and Energy (MLME), Ministry of Commerce and Industry (MoCI), Liberia Electricity Corporation (LEC), Rural and Renewable Energy Agency (RREA), Liberia Petroleum Refining Company (LPRC), National Oil Company of Liberia (NOCAL), and the Environmental Protection Agency (EPA). State-owned operators including the LEC and micro-utilities have been self-regulating. The result has been high electricity cost and inadequate services, which are major constraints to Liberia’s economic growth and poverty reduction.

To address the situation, the National Energy Policy (NEP) of Liberia was approved in 2009. It provides among others, liberalization of the sector and separation of policy, regulation, and operation.

The National Energy Policy led to the enactment of the 2015 Electricity Law of Liberia (ELL) on October 26, 2015. The ELL provides the legal basis for the establishment of the Liberia Electricity Regulatory Commission (LERC) as the National Regulator. LERC is an independent agency with respect to its budget, management, staffing and the exercise of its duties and authorities as prescribed in Section 13.3 of the Law.

LERC’s function, as regulator, is to issue licenses, approve tariffs, ensure liberalization of the sector, improve service delivery, protect consumers and create a vibrant electricity sector.

Square D OEM QED-2 I-Line Switchboard Components
Single row and double row I-Line interior products
Engineered to help you create high quality, custom switchboard layouts to meet your customers’ unique business needs.

President Joe Biden’s climate agenda is likely to deliver blackouts for millions, according to a North Dakota state assessment of new rules finalized by the Environmental Protection Agency (EPA).

In May, the North Dakota Transmission Authority published a report with the firm Always On Energy Research examining implications of the EPA’s greenhouse gas regulations on the state’s power grid.

The EPA’s strict emissions standards, researchers reported, “is not technologically feasible for lignite-based power generation facilities.” State investigators say the EPA’s Greenhouse Gas Rule, finalized this spring, will force the premature retirement of reliable coal plants so they can be replaced by intermittent, weather-dependent sources such as wind and solar. //

“We determined the closure of lignite-fired powered plants,” they added, “would increase the severity of projected future capacity shortfalls, i.e. rolling blackouts.”

Larry Behrens, the communications director for the energy non-profit Power the Future, called less power and higher energy prices “two guarantees of Joe Biden’s energy failures.”

“Sadly, the threat of blackouts is the logical result of efforts to destroy reliable energy sources in favor of intermittent wind and solar,” Behrens told The Federalist.

The North Dakota state findings corroborate warnings issued by the North American Electric Reliability Corporation’s (NERC) 2024 Summer Reliability Assessment published last month. The Atlanta-based non-profit cautioned that the power grid will face extreme stress under higher-than-average temperatures expected this summer. //

Alex Epstein @AlexEpstein
·
Replying to @AlexEpstein
To function at its potential, AI requires massive amounts of power. E.g., state-of-the-art data centers can require as much electricity as a large nuclear reactor. ["several gigawatts"]
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Alex Epstein @AlexEpstein
·
Electricity demand from US data centers already doubled between 2014 and 2023. Now with the fast growth of energy-hungry AI, demand from data centers could triple from 2.5% to 7.5% of our electricity use by 2030, according to Boston Consulting Group.
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3:17 PM · May 23, 2024

Cross reference between NEMA and IEC schematic diagram symbols

Mecheri, Yacine and Nedjar, Mohamed and Lamure, Alain and Aufray, Maëlenn and Drouet, Christophe Influence of Moisture on the Electrical Properties of XLPE Insulation. (2010) 2010 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (CEIDP) . pp. 1-4. ISSN 0084-9162 //

. The goal of this paper was to investigate the eventual degradation of XLPE insulation under humidity effect by characterization techniques. For this purpose, measurements of dielectric losses factor, relative permittivity, volume resistivity and dielectric strength were performed.

(ii) Preimmersing XLPE insulation in tap water prior to electrical aging at room temperature results in a reduction of more than 50% in the breakdown voltage. The preimmersion increases the moisture content, particularly liquid water at room temperature, resulting in increased degradation. (iii) Preimmersion does not have any effect on the breakdown voltage of cables electrically aged at 70°C or 90°C. (iv) For some aging conditions, the short term breakdown voltages of aged cables give no indication of the number of and times to breakdown of the cables during the electrical aging. (v) Direct voltage is quite sensitive to degradation of XLPE by the combined action of moisture and electric stress. Care must be exercised when dc testing aged cables in service.