In the present day, when energy drives our lives, we need to keep a check on our consumption and control the same. Our customers at Powerpoint Engineering regularly pose questions relating to Energy Metering. In this article, I have put together the following information that I hope will give you a better understanding of Energy Metering and the process of monitoring and tracking energy consumption. Continue reading →
Today’s industrial life extensively uses all types of electronic devices such as monitors and servers that require a lot of power. Our customers at Powerpoint Engineering regularly pose questions relating to power usage and the costs involved. I have put together the following information that I hope will give you a better understanding of how efficiently we utilise power, keeping the cost-effectiveness in mind. One way to analyse this through consideration of the power factor.
There are two aspects to power – active and reactive. Active or real power is the power used in all electrical appliances. This is expressed in kilowatts (kW). Reactive power is the power needed to generate and sustain a magnetic field in order to operate. The reactive and active powers together comprise the apparent power.
Power factor is the ratio of working power to the apparent power. It does not have a dimension and its value ranges from 0 to 1. An appliance with a high PF utilises power more efficiently than a one with a low PF.
To identify the energy consumption of devices, energy meters are used. There are three general types of energy meters. They are:
Induction Type Energy Meters
Electronic Energy Meters
The first two types mentioned are conventional energy meters. They measure the power used by both domestic and industrial sectors. However, a smart meter, measures not just the energy consumed but also indicates when it was consumed (Time of Use – TOU). In addition, it is also capable of measuring consumption of natural gas or water.
Smart meters enable bidirectional communication. They can transmit data such as parameter values, alarms, etc. to utilities for retrieving information such as reconnect/disconnect instructions and meter software upgrades. Modems are fitted onto these meters to facilitate communication through wireless media. Revenue metering helps prevent power theft.
Measurement of Power Factor
The Commissioner for Energy Regulation – Ireland (CER) clearly define the accuracy requirements of revenue electrical energy metering systems and their components for kWh & kVArh over a range of supply voltages and over a range of supply kVA thresholds. Section 5.7.1 of the CER metering code – (http://www.cer.ie/docs/000820/CER%20Metering%20Code.pdf ) states:
“The accuracy of the various items of measuring equipment shall conform to the relevant national IEC Standards (or equivalent European Standards).”
There are different Methods of Measurement for Power Factor:
Displacement Power Factor (DPF) is defined as the Cosine of the Phase Angle between Supply Voltage and Load Current.
Effective Power Factor (PF) is the ratio of Active Power / Apparent Power.
Generally DPF is almost equal to PF. However, in a situation where the connected load contains Harmonic Distortion, these power factor values can be quite different.
There is a lack of clarity from IEC and the CER for which method of power factor measurement should be used when the connected load current contains harmonics. It is unclear if the mentioned Wattless Energy [kVArh] in section 5.7 of the CER Metering Code is the reactive energy component at 50Hz only, or over the EN50160 Voltage compliance spectrum of 50 harmonics. The kVAr will vary significantly and consequentially, so will the power factor.
This affects billing costs and how Power Factor Correction (PFC) equipment is configured and may operate optimally.
The relevant IEC standard for Electricity Metering Equipment is IEC 62053-24, in particular Annex E, E1. A summary is highlighted below. The IEC do not yet have a standard for measurement of power factor / reactive power in harmonic environments. They have stated that it a known issue, but a standard has not been developed yet.
“Excerpt from IEC Standard 62053-24:
Treatment of harmonics and tests for harmonics
E.1 Non-sinusoidal conditions and reactive power definition
Many meter types designed prior to the establishment of this standard exhibit large differences in metered reactive energy under non-sinusoidal conditions (in the presence of harmonics). Earlier standards for electricity meters for reactive energy were based on a definition of reactive energy for sinusoidal currents and voltages. Consequently, they could not specify any requirements for the performance under non-sinusoidal conditions. In order to ensure that the differences in measurement results between different meter types remain within reasonable limits, it is necessary to base the standard on a definition of reactive energy that allows including performance requirements in the presence of harmonics. There are many definitions available for reactive, or non-active, power under non-sinusoidal conditions. Some of them are more theoretical, some are very suitable for some particular applications, but none of them have the same wide usefulness as the definition of reactive energy under sinusoidal conditions. A wide consensus on a single definition of reactive power under non-sinusoidal conditions, suitable for a wide spectrum of applications is not expected in the foreseeable future. ……. Harmonics have no particular phase angle and do rather average out than add in the network. This makes billing for harmonic current controversial. Additional standards for meters for non-active energy based on other definitions may be developed in the future.”
(IEC Standard 62053-24)
For more information please contact Garrett Kelly BSc MIET at [email protected], Senior Project Engineer at Powerpoint Engineering or call us on 057 866 2162.
From minor control trips right down to compressor and transformer failures, harmonics can have an impact on every type of HVAC equipment. Surprisingly, harmonics is something that quite often can be overlooked.
Harmonic currents and the electrical distribution system
Harmonic currents flow in a circuit at multiples of the fundamental 60 hertz (Hz) frequency. For example, current flowing in a circuit at 180 Hz is the third harmonic (60 Hz multiplied by 3). These currents are not indicated on multimeters and therefore are usually not detected until unusual control and equipment problems start to happen. Comparing these current readings from an average-responding meter to that of a good quality true-rms meter on the same circuit will help in indicating harmonic issues. An average-responding meter will specify only the 60 Hz current, the true-rms meter can indicate a combination of 60 Hz and harmonic currents.
The production and reflection of these harmonic currents back into the electrical distribution system can cause problems such as:
Improper operation of control circuits
Faulty shut-downs of electronically controlled chillers and air handler units (AHUs)
Overheating of solenoid coils resulting in a replacement being required
Overheating of 480 volt transformers (supplying 208Y/120 volt HVAC systems)
Overheating of fan and chilled water pump motors
It is now possible for professional technicians and engineers to isolate harmonic issues back to their source and then mitigate their effects by either replacing the problematic item or by installing harmonic filters.
Modern electronic circuits must convert the supplied 60 Hz alternating current (ac) into direct current (dc) since the electronics operate using dc voltage and current. The waveform of the current drawn by these electronic loads reveals that the current waveform does not correspond to the voltage waveform applied. Thus, such electronic loads are referred to as “nonlinear” loads. These nonlinear loads produce the harmonic currents reflected back into the system. Harmonic currents appear across a wide spectrum, but generally diminish as the frequencies get higher and higher. See Figure 1.
Figure 1. Nonlinear load. Observing one single-phase set of voltage and current sine waves drawn by a variable frequency drive (VFD) readily shows that the current waveform (lower) does not conform at all to the voltage waveform applied. Such nonlinear loads produce harmonic currents that flow into the distribution system.
While different harmonic frequencies produce their own unique effect in a circuit, when combined they can distort the original 60 Hz sine wave. Distorted power at the input point to electronic equipment can create the erroneous trips and alarms that sometimes occur in control circuits. Some harmonic currents will produce excessive heat while other harmonics produce a reverse torque in motors therefore reducing efficiency and overheating motors.
Troubleshooting in any circuit means properly identifying the root cause of the problem and then isolating the source. If this routine troubleshooting does not reveal the problem you will have to consider looking for harmonics:
Measure with a clamp meter that is capable of indicating total harmonic distortion (THD). THD for voltage should not exceed 5 %. THD for current will run considerably higher.
Use a power quality analyzer to further investigate the magnitude and effects of the individual harmonics. Power quality analyzers are available for both singlephase and three-phase circuits. In addition to measuring harmonics, power quality analyzers record other disturbances that can cause malfunction of control circuits. For example, “swells” are increases in voltage above the rated values and can damage equipment. “Dips” are decreases in the applied voltage and will causes spurious shutdowns and false alarms in variable frequency drive (VFD) and programmable logic controller (PLC) circuits.
THD and harmonic levels should be measured at the point of common coupling (PCC) – the point at which the nonlinear loads suspected of causing the problem connect to the remainder of the distribution system. Look for THD for voltage approaching 5 % and check for the presence and the levels of different harmonic frequencies. See Figure 2.
Figure 2. Harmonics. In this power quality analyzer screenshot, the harmonic frequencies appear on the harmonic axis. The percent to which the specific harmonic frequency is a component of the fundamental 60 Hz frequency appears on the vertical axis. The cursor has been placed over the third harmonic frequency, and this third harmonic current appears to represent approximately 25 % of the 60 Hz frequency.
What to do when you find excessive harmonics
If you find excessive harmonics, review each case individually before making a decision on a course of action. You can buy harmonic filters and put them as close as is possible to the equipment that is producing the harmonic currents. You can consult the manufacturer of the equipment or an outside engineering consultant to recommend the most suitable harmonic filter for the problem.
Another alternative is to isolate the problem equipment using an isolation transformer. Relocating either the nonlinear load causing the problem or the affected circuit to another distribution panel may help. For example, if the affected controls are supplied from the same panelboard as the nonlinear load causing the problem, moving the control circuit to another panelboard may help alleviate the problem. Harmonic problems tend to diminish moving farther away from the nonlinear load.
Powerpoint Engineering were called to investigate electrical
power quality issues in November 2019 at a meat factory in Cork.
It was found on site that the automatic Power Factor Correction (PFC) equipment was overheating and had a history of repeated failures of capacitors and switching contactors.
Some components were replaced and maintenance was performed on the equipment. It was found that the PFC bank was constantly running at full capacity, and under-dimensioned for the site electrical load. A report was issued to the client that the equipment was at end of life and should be replaced.
In February 2020, the equipment finally failed, beyond
At this time it was decided by the factory to replace the equipment. New equipment was dimensioned (Electrically and physically) from the previous maintenance report. A turnkey offer was made to the client for supply, installation and commissioning of the new equipment. The factory ordered the equipment in late March. The equipment was supplied in mid-April, installed and commissioned the same week.
During the 8 week period while the PFC was inactive, the factory bore electrical utility bill penalties of almost €2,000 per month for ‘Bad Power Factor’ charges.
At commissioning, it was noted that there were Panel Mounted Energy meters installed on the incoming supplies. It could be seen that the connected load had > 440kVAr of Watt-less Power component. Once the PFC unit was commissioned and switched on, this Watt-less Power was reduced to 40kVAr and the site power factor was corrected to 0.99 lag. This now has the benefit of eliminating the utility bill of ‘Bad Power Factor’ charges and also the MIC/kVA demand is reduced.
Pay-back/Return on investment calculations were made very easy, with a utility bill reduction of €2,000 per month.
‘If the number of wattless units you use in a single billing period exceeds a limit of one-third of all your general units (both day and night), then a charge will apply.’ (www.electricireland.ie April 2020)
Email us for further information or call us on 057 866 2162, we’d be happy to answer any queries you might have.
At Powerpoint Engineering we offer energy monitoring equipment and the best solution to all of your energy monitoring and power quality requirements. We have over 24 years’ experience in all aspects of the electrical industry and 20 years’ experience in energy monitoring and power quality.
We supply leading
energy monitoring hardware with technical support on all energy meters and sensors. We also supply monitoring equipment to monitor gas and water
Our sales team can
offer a site survey to discuss any technical requirements you may have, to
deliver the best metering solutions.
We offer a full
turn key energy monitoring solution for new builds and existing systems, with
our online energy monitoring platform or a software that can be housed
at your premises, fully designed to meet your requirements with communication
installation and configuration.
We can install a
non-intrusive energy monitoring system with design, communication installation
and configuration, where the client may have critical loads that a power
shutdown is not possible or vies able.
All of our metering
systems can be integrated into existing metering and BMS systems.
With the new
design of current transformers and energy meters. They are now more compact and
safer than ever before.
monitoring system with our online platform
With our online
Energy Monitoring platform, it is now easier than ever to monitor consumption
of energy remotely. Our online platform and energy metering system makes
it easier for the user to generate reports and monitor the power quality of their
plant or power generation station.
We have installed
our systems throughout Ireland and Europe. Our Clients include universities, pharmaceutical & bio medical industry, the catering &hospitality
sector, utilities sector, hospitals, schools, product production plants and data
centres. Also, in some of the most remote parts such as broadcasting
stations, Windfarms and Water treatment plants.
monitoring energy usage:
usage in most cases can have a direct correspondence to production and turn
Monitoring can produce a trend, overtime it could show early indication of
machine failure in pumps and motors.
In recent years, there has been an explosion in data centre development in Ireland.
Leading the way was Microsoft, which developed a vast data centre at Grange Castle near Clondalkin in 2009.Now nearly all of the big technology companies such as Amazon and Google have a data centre footprint here.
There are plans for more Data Centres such as the giant €850 million data centre Apple is planning in Athenry, Co Galway.
Electricity or power is now one of the key considerations in selecting an appropriate site and in the on-going management of a Data Centre. Electricity or power is one the main costs involved in operating a Data Centre and facility managers use experts such as Powerpoint Engineering to ensure that there are no power quality issues at their Data Centre.
So what are the key ingredients in providing this specialised service?
Use of suitable and compliant equipment (eg. IEC 61000-4-30, Class A);
Measurement according to standards (eg. EN50160-2010 or client specified detailed measurement requirements)
Powerpoint Engineering is the proven leader in this area having assisted numerous Data Centres particularly during the commissioning stage. Their team has the necessary expertise in power quality surveys, power quality monitoring and providing power quality solutions.
In terms of compliant equipment, the simultaneous recording of all Power Quality parameters with a good quality portable power quality analyser allows for repetitive guaranteed measurements during data centre commissioning. When commissioning Generators, UPS systems, and Switchgear Equipment, the use of reliable, easy to use, standards compliant measurement equipment is very important. There are some good options available of comparable instruments. Some that we recommend include Unipower from Sweden which has the Unilyzer U900 & U902 instruments, both comply with IEC 61000-4-30 Class A for Power Quality measurements. Dranetz, which is part of Gossen-Metrawatt, offer the Power XPlorer, and Fluke has their popular Fluke 435-II.
When measuring to standards or client specified requirements, the specified scope of works detailing the list of parameters to be measured, such as kVA, kVAr, kW and harmonics levels, is critical. These commissioning tests are expensive so it is also imperative that all required data is measured and collected in an accurate, dependable and repeatable fashion. For example, a generator load test may need to run for 20 hours, with a large commissioning team and a large quantity of fuel to be used! Supplementary data is also captured such as fast transient disturbances. This information can be of used for troubleshooting other subsequent issues occurring during commissioning, such as electronic component failure or malfunctions.
For more information please contact Garrett Kelly BSc MIET at [email protected], Senior Project Engineer at Powerpoint Engineering or call us on 057 866 2162.
Efficient energy metering and management is a key concern that continues to challenge companies across the world. Rising energy costs have forced them to make better use of building automation, metering, data acquisition and processing systems to track consumption, wastage and demand at a granular level and optimise energy utilisation. Many organisations are now exploring new alternatives such as distributed energy resources (DERs) to address their growing energy needs.
ISO 50001 is an international standard that offers a comprehensive framework to setup, apply maintain and enhance the effectiveness of Energy Management Systems (EnMSs) on a continuous basis. Based on the Deming Cycle, the framework requires organisations to carefully plan and strategise their energy management efforts before implementing them and improving energy efficiency, until energy targets are achieved.
The objectives or targets of an energy management initiative must first be finalised before embarking on action. It is important to decide what an organisation or utility service provider wishes to accomplish using energy data from metering systems and then address the question of how best to achieve the intended results.
The adoption of ISO 50001 and compliance requires companies to:
Define objectives and targets
Detail action plan
Identify energy benchmarks/baseline
Establish Key Performance Indicators (KPIs)
Formulate a framework to monitor, measure, and analyse energy data
Conduct periodic reviews to improve performance
Benchmarks and KPIs are two critical aspects that determine the success of energy management initiatives. Knowing what to measure and compare is as important as knowing the goal the company has set out to achieve.
Energy benchmarks serve as a standard against which energy efficiency of a given site/location is compared. These can either be energy data from the same site (usually historical) or other external sites or locations with similar functions and sizes.
Key performance indicators, on the other hand, are specific parameters that help measure energy efficiency. These are directly mapped to energy data collected by the different metering systems on site. KPIs usually are site-specific and vary based on the size and function of the location. Defining the right KPIs, therefore, is important to get a clear picture of energy demand, supply and consumption at a given site.
For example, data centres typically will be interested in tracking power usage effectiveness, cooling efficiency, UPS efficiency and use, and energy efficiency of servers. Monitoring the density of light, efficiencies of fans, heating/cooling systems, pumps, etc. seem more relevant in residential/office buildings.
Determining the Right Benchmarks and KPIs
Facility managers are usually adept at determining site-specific KPIs. However, for those who need assistance, answering a few simple questions and working forward from actual energy consumption data often helps identify relevant KPIs without much difficulty. This can be done in just a few steps.
Determine Significant Energy Uses (SEUs)
Spot factors that influence energy use
Note consumption metrics and decide on what can be metered
Establish energy KPIs for each SEU based on energy drivers
Decide on benchmarks or references (internal and external) to compare energy performance
Define realistic goals to achieve
Working forward from energy consumption or SEUs at the granular level, the goal-setting exercise for energy management becomes even more meaningful and relevant. Mulling on a few significant queries at each step of the process has been observed to prove valuable:
What are the site-specific general and significant energy uses? Significant energy uses such as HVACs, gas-based heaters/boilers, lighting, heavy equipment/machinery, production plants/lines are key points that need close monitoring and control for effective energy management.
What factors drive or influence energy use? Energy consumption tends to vary based on several factors such as floor area or expanse of the site, occupancy or use of site, the number of machines or production units in a manufacturing facility, external weather conditions, etc.
How much energy does each of factors demand? Is it possible to control them? If at all, then how? Is it possible/necessary to meter energy consumption? Meters for lighting (kWhs), gas consumption (MMBtu), production lines and HVAC use (MWhs) are available to individually measure each SEU.
What performance indicators to monitor to track each SEU? Energy used or energy costs per unit of production is widely used in manufacturing facilities. Energy used for lighting per unit of occupancy. Total energy consumption for floor area. HVAC energy/degree days (based on external weather conditions).
Are there any guidelines or recommended best practices for energy management?How are others with similar site size and function implementing energy management? Which other locations can serve as benchmarks? How has internal energy performance improved over time? What is the internal baseline against which current performance should be compared?
Answers to these and other relevant site-specific queries automatically will pave the way for clear, achievable, and realistic energy efficiency goals to work towards.
Technological advancements now facilitate data-driven decisions, making it easier for decision makers to base their actions on real-time data readily available via the cloud. With energy management goals, KPIs and benchmarks in place, it is possible to map hardware units to automated systems and enterprise software and suitably use the metering infrastructure and sensors to gather and analyse energy data, monitor and control consumption, identify and minimise waste and improve the energy efficiency of a specific site/location. Guided by the ISO 50001 framework, companies will be able to address their specific energy concerns in an effective manner.
The Dublin City Council is the authority responsible for the local government in the city of Dublin. With its 63 elected members the city council holds responsibility of the fire brigade, housing, roads, urban planning, culture and environment among other sectors, with an annual budget of nearly one billion euro.
In the end of 2018 Powerpoint Engineering, the local representative in Ireland for Unipower Systems, installed a complete PQ Secure system at the main feeder for the main drinking water supply pumping station for Dublin. The system will not only monitor the everyday power quality parameters and alarm the engineering offices when a PQ event is detected, the system will also provide information to the council needed to take the right actions on energy saving investments.
The installation also included Unipower’s Substation display (22-0105) for easy and fast access to all power quality data and reports at the feeder room.
For more information please contact: Garret Kelly at Powerpoint Engineering Ltd, [email protected]
Powerpoint Engineering Ltd. is very pleased to announce that we will be exhibiting at this years Data Centres Ireland Event. Data Centres Ireland 2015 is taking place in the RDS, Dublin and will run from Tuesday 10th to Wednesday 11th November.
This exhibition will cover all aspects of planning, designing and operating your datacentre, storage facility, server room or solution.
We will be demonstrating a range of products & services suited to your datacentre including PAT Testers, Thermal Imaging Cameras, Power Quality & Energy Monitoring Equipment, Electrical Testers, Arc Flash PPE and Lockout Tagout Equipment.
We will also be providing information on our PAT Training and Thermal Imaging Training (Level 1 & 1 Day Courses).
Come and see us at Stand 215 and find out how we can help you.