According to a recent study published by the Electric Power Research Institute (EPRI), large industrial facilities in the US lose over $100 billion every year due to power problems including power supply variations and voltage disturbances. When the lights flicker at home, it’s an annoyance. But when power is disturbed at a factory, it can cause malfunction and early breakdown of expensive equipment.
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Tomi Engdahl says:
Neutral woes
http://www.edn.com/electronics-blogs/benchtalk/4458329/Neutral-woes?utm_content=buffer6c562&utm_medium=social&utm_source=plus.google.com&utm_campaign=buffer
noticed some of my lights were randomly flickering. Right away, I was concerned that we’d lost our 7.2 kV neutral again – something I wrote about in New house electric woes revisited.
To better characterize what was going on, I hooked my scope up to the AC line. Yeah, that felt a bit scary, but the pre-worry was out of proportion to just actually doing it. It’s not like I’ve never scoped the line before…geez (I didn’t connect probe ground, instead relying on the scope’s AC ground).
I then realized I’d get a lot more out of the experience by scoping both phases of the line
The complementary waveforms scream “bad neutral!” (the neutral center-tap from my transformer secondary that is, unlike the missing HV neutral of my past woe).
I walked the long 240V line (75m-ish) from the house to the transformer, and… TaDa. A small tree was resting against the line just steps away from the transformer. Though no damage was visible, the coincidence seemed too great.
electric utility arrived a few days later (the day after I called in a panic because of extreme flickering, and reading peaks up to 150V – on a slow DMM!),
http://www.edn.com/electronics-blogs/benchtalk/4440265/New-house-electric-woes-revisited
Tomi Engdahl says:
Introduction to Harmonics – Effect of Harmonics on Power System
https://www.electricaltechnology.org/2018/02/harmonics.html
Tomi Engdahl says:
Sensors and Power Conditioning for Industry
https://www.eeweb.com/profile/steve6366/articles/sensors-and-power-conditioning-for-industry?utm_source=newsletter&utm_campaign=link&utm_medium=EEWebEngInsp-20191219
Power conditioning acts as an interface between the power source and the load, which in most industrial applications performs critical functions, providing equipment protection and output waveform correction against noise, voltage fluctuations, radiofrequency, and electromagnetic interferences.
The increasing industrial use of electrical and electronic equipment has led to a rise in the demand for electricity, which in such applications must be as much freedom as possible from disturbances, drops, or undesirable harmonic components. In industrial production processes, it is mandatory to guarantee the availability of electricity uninterruptedly and regularly — an equipment downtime would, in fact, result in lost productivity, with inevitable consequences on the company’s profits. To mitigate these risks, the most commonly adopted solution is to install a power-conditioning system. This electronic device has the task of monitoring the input voltage (tri-phase voltage from the electrical distribution network), ensuring that the connected loads are safely protected by spikes, surges, sags, ground noise, undesired harmonics, and other types of phenomena that can interrupt the functioning or damage the sensitive electrical and electronic equipment. A power-conditioning system for industrial applications is able to detect any anomalies in the supply voltage. By applying the appropriate corrective actions in a very short time, it ensures the supply of a regular and reliable three-phase power source. The response times are very fast (in the order of milliseconds), while the output power varies from a few hundred VA up to about 1,000 kVA, with an input voltage between 380 and 415 VAC. In summary, power conditioning acts as an interface between the power source and the load, which in most industrial applications performs critical functions, providing equipment protection and output waveform correction against noise, voltage fluctuations, radiofrequency, and electromagnetic interferences.
Tomi Engdahl says:
https://come4concepts.com/what-is-power-factor-pf/
Tomi Engdahl says:
Power-Quality Monitoring (Part 1): The Importance of Standards-Compliant PQ Measurements
June 14, 2023
PQ measurements have become ever-more critical in today’s electric infrastructure. This article dives into why they’re so important, reviews areas of application for PQ monitoring, and covers the IEC standard for power quality and its parameters.
https://www.electronicdesign.com/technologies/power/article/21267833/analog-devices-powerquality-monitoring-part-1-the-importance-of-standardscompliant-pq-measurements?utm_source=EG+ED+Analog+%26+Power+Source&utm_medium=email&utm_campaign=CPS230615020&o_eid=7211D2691390C9R&rdx.identpull=omeda|7211D2691390C9R&oly_enc_id=7211D2691390C9R
What you’ll learn:
What are parameters of power quality?
Applications best served by PQ monitoring.
Comparing Class A and Class S for measurement devices.
Power quality (PQ) has found renewed interest due to changing power-generation modes and consumption dynamics. Unprecedented growth in renewable sources at different voltage levels has compounded PQ-related issues.
Consumption patterns have also seen a wide transformation due to unsynchronized loads added at multiple entry points of the grid and voltage levels. Some examples include electric-vehicle (EV) chargers that can require hundreds of kilowatts, and the large number of data centers and their related equipment, such as heating, ventilation, and air conditioning. In industrial applications, arc furnaces that run by variable-frequency drives, switching transformers, etc., not only add a lot of unwanted harmonics to the grid, but are responsible for voltage dips, swells, transient brownouts, and flicker, too.
PQ Monitoring Areas of Application
Power-quality monitoring is often seen as a cost-saving strategy for some business sectors and a critical activity for others. Power-quality issues can arise in a broad range of electric infrastructure (Fig. 2). As we’ll discuss later, PQ monitoring is becoming increasingly critical in spaces such as electric generation and distribution, EV charging, factories, and data centers.
Electricity Utility Companies, Electricity Transmission, and Distribution
Utility companies serve consumers with distribution systems such as generating stations, which are power substations that supply electricity via transmission lines. The voltage supplied via these transmission lines is stepped down to lower levels by substation transformers, which inject certain harmonics or interharmonics to the system. Harmonic currents in distribution systems can cause harmonic distortion, low power factor, and additional losses, as well as overheating in the electrical equipment,2 leading to a reduction in the lifetime of equipment and increases in cooling costs.
Nonlinear single-phase loads served by these substation transformers deform the current’s waveform. The unbalance of nonlinear loads causes additional losses on power transformers, additional load of neutrals, unexpected operation of low-power circuit breakers, and incorrect measurement of electricity consumed.3 Figure 3 illustrates the effect of these linear loads.
Electricity generation by wind and photovoltaic (PV) solar systems injected into the grid create several power-quality problems as well. On the wind generation side, wind intermittency generates harmonics and short-duration voltage variations.4 The inverters in PV solar systems create noise that can produce voltage transients, distorted harmonics, and radio-frequency noise because of the high-speed switching commonly used to increase the efficiency of the energy harvested.
EV Chargers
Electric-vehicle chargers can face multiple power-quality challenges, both in power sent to and from the grid (Fig. 4). From a power distribution company perspective, power electronics-based converters used in EV chargers inject harmonics and interharmonics. Chargers with improperly designed power converters can inject direct currents (dc). In addition, fast EV chargers introduce rapid voltage changes and voltage flicker into the grid.
From the EV charger side, faults in transmission or distribution systems lead to voltage dips or interruption of supply voltage to the charger. Reduction of voltage from the EV charger tolerance limits will lead to activation of undervoltage protection and disconnection from the grid (which leads to a very bad user experience).5
Factories
Power-quality problems caused by power-supply variations and voltage disturbances cost approximately $119 billion (U.S.) per year for industrial facilities in the United States, as per an Electric Power Research Institute (EPRI) report.6 Moreover, 25 EU states suffer an equivalent of $160 billion (U.S.) in financial losses per year due to different PQ issues, according to the European Copper Institute.7 These figures are linked to subsequent downtime and production losses as well as the equivalent of intellectual productivity losses.8
To detect and record these disturbances inside a factory installation, it’s necessary to have PQ monitoring equipment in several points throughout the electric installation or, even better, have it at the load level. With the arrival of new Industry 4.0 technologies, PQ monitoring at the load can be addressed by industrial panel meters or submeters to get a comprehensive view of the quality of the power delivered to each load.
Data Centers
Presently, most business activities depend on data centers in one way or another to provide email, data storage, cloud services, etc. Data centers demand a high level of clean, reliable, and uninterrupted electricity supply. PQ monitoring excellence helps managers prevent costly outages and helps manage equipment maintenance, or replacement, required due to issues on the power-supply units (PSUs).
The integration of uninterruptible-power-supply (UPS) systems into rack power distribution units (PDUs) represents another reason to add PQ monitoring to IT racks inside the data center. This integration can provide visibility to power issues at a power-socket level.
UPS system failure, including UPS and batteries, is the primary cause of unplanned data-center outages, according to a report by Emerson Network Power.10 Around a third of all reported outages cost companies nearly $250,000.
Apart from these issues, PSUs also face interferences that come in multiple forms. Among them are voltage transients and surges; voltage swells, sags, and spikes; imbalance or fluctuations; frequency variation; and poor facility grounding.
PQ Standards Defined
Power-quality standards specify measurable limits to the electricity magnitudes as to how far they can deviate from a nominal specified value (Fig. 5). Different standards apply to different components of the electricity system.
Specifically, the International Electrotechnical Commission (IEC), in the IEC 61000-4-30 standard, defines the methods for measurement and the interpretation of results of PQ parameters of alternating-current (ac) power systems. The PQ parameters are declared for fundamental frequencies of 50 and 60 Hz. This standard also establishes two classes for measurement devices—Class A and Class S:
Class A defines the highest level of accuracy and precision for the measurements of PQ parameters and is used for instruments requiring very precise measurements involving contractual matters and dispute resolution. It’s also applicable to the devices that need to verify compliance of the standard.
Class S is used for PQ assessment, statistical-analysis applications, and diagnostics of PQ problems with low uncertainty. The instrument in this class can report a limited subset of the parameters defined by the standard. The measurements made with Class S instruments can be done on several sites on a network, on complete locations, or even on single pieces of equipment.
The IEC 61000-4-30 standard defines the following PQ parameters for Class A and Class S measurement devices:12
Power frequency
Magnitude of the supply voltage and current
Flicker
Supply-voltage dips and swells
Voltage interruptions
Supply-voltage unbalance
Voltage and current harmonics and interharmonics
Rapid voltage change
Underdeviation and overdeviation
Mains signaling voltage on the supply voltage
Key Differences Between Class A and Class S Defined by the IEC 61000-4-30 Standard
Although Class A defines higher levels of accuracy and precision than Class S, the differences are beyond just levels of accuracy. Instruments must comply with requirements such as time synchronization, quality of probes, calibration period, temperature ranges, etc.
Tomi Engdahl says:
Aeronautical Ground Lighting
https://www.internationalairportreview.com/article/1722/aeronautical-ground-lighting/
Aeronautical Ground Lighting (AGL) is the collective denomination for the whole set of ground installed luminaires and related ancillaries meant to be used as visual aids by aircraft pilots and eventually, other users of aerodrome facilities.
Specifically, AGL is formed by a number of aeronautical ground lights, arranged in accordance with precise patterns. An aeronautical ground light is any light specially provided as an aid to air navigation, other than a light displayed on an aircraft.
International standards applicable to AGL were first established by the International Civil Aviation Organisation (ICAO). Nowadays, both the European Committee for Electrotechnical Standardisation (Comité Européen de Normalisation Electrotechnique, CENELEC) and the International Electrotechnical Commission (IEC) have dedicated Technical Committees that have published a number of International and European standards regarding AGL.
The AGL system and its components
The whole AGL system encompasses the lighting of runways, including their approaches, and associated taxiways and aprons.
The lighting subsystems related to the runway include approach; visual approach path indicators; runway threshold, edge, end, and as required by operations minima, touchdown zone and centre line.
AGL is composed of luminaires plus their supporting structures, related civil engineering works, such as foundations, as well as power supplies.
Since the light sources used by the luminaires are usually electric lamps (normally halogen incandescent bulbs), power supplies provide the proper electrical power to lamps.
The lamps are connected to and powered by an electrical circuit. The luminous output of a series of incandescent lamps of a given rated power is dependent on the current flowing through their filaments. Hence constant current in the circuit means constant luminous intensity. That is why the AGL circuits are traditionally configured as constant current series circuits.
The constant current is provided by a specific power supply, the constant current regulator (CCR), which powers the series circuit. This circuit is composed of:
the proper cable, normally high voltage cable,
the isolating series transformers, usually one per each luminaire, that isolates the low voltage or luminaire side from the high voltage primary circuit fed by the CCR. Isolating transformers also provide continuity to the series circuit in case a lamp is burned out.
Operation and maintenance
IEC 61821, Electrical installations for lighting and beaconing of aerodromes – Maintenance of aeronautical ground lighting constant current series circuits. (International Standard). This international standard applies to the maintenance of AGL constant current series circuits and concentrates on providing the appropriate safety procedures. It is mainly concerned with safety of persons.
IEC/TS 62143, Electrical installations for lighting and beaconing of aerodromes – Aeronautical ground lighting systems. Guidelines for the development of a safety life – cycle methodology.
This technical specification is based on the safety life – cycle methodology described in IEC 61508.
According to the parallel voting procedure between IEC and CLC, International Standards IEC 61822 and IEC 61823 have been adopted as EN in the European Union. Hence they are to be considered mandatory for public procurement purposes (see end of 5.2 above).
Aeronautical ground lighting system study: field measurements and simulations
https://ietresearch.onlinelibrary.wiley.com/doi/full/10.1049/iet-gtd.2015.1536
Aeronautical ground lighting (AGL) systems are single-phase series circuits where constant current regulators supply transformers and luminaires. These systems provide visual reference to aircraft during airport operations. There is a lack of AGL system models and measurements in the literature to study AGL system behaviour and predict their response to electrical events and future technological changes. The study contributes to AGL system modelling with an equivalent circuit useful to study AGL system concerns by Matlab/Simulink simulations. It also presents field measurements taken at Reus airport (Catalonia, Spain) for the validation of the proposed model and understanding of AGL system behaviour in the event of luminaire failure.
Tomi Engdahl says:
https://www.electronicdesign.com/resources/industry-insights/article/21275020/electronic-design-engineers-look-to-adopt-a-more-sustainable-approach-to-electronic-design?utm_source=EG+ED+Connected+Solutions&utm_medium=email&utm_campaign=CPS231005093&o_eid=7211D2691390C9R&rdx.identpull=omeda|7211D2691390C9R&oly_enc_id=7211D2691390C9R