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Regulatory Guidelines to set up Voltage Quality Monitoring


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This session is part of the Clean Energy Regulators Initiative Webinar Programme.

Theme 2 - Pressure Points

Module 2: Voltage Quality Regulation

Voltage quality, sometimes called power quality or technical quality, covers a variety of disturbances in an electrical power system. It is mainly determined by the quality of the voltage waveform and it is an important aspect of the electricity service.

Customers are becoming increasingly sensitive to disturbances in voltage quality. This issue is particularly important taking into account the new regulatory frameworks which put strong emphasis on cost reduction, thereby potentially jeopardizing quality. When setting up a quality regulation framework, there are a number of basic issues that need to be considered first. This understanding is crucial in order to make the right choices in order to arrive at an effective voltage quality regulatory system. It is important to clearly define voltage quality and develop suitable indicators.

This presentation assesses the issue of what regulators need to consider whenever establishing a voltage quality regulatory framework for distribution networks (i.e. up to 35 kV). It presents a general set of guidelines that regulators could consider in introducing and developing voltage quality regulation. Regulation of five important voltage quality dimensions is considered: short-interruptions, voltage dips, flicker, supply voltage variation and harmonic distortion.

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Regulatory Guidelines to set up Voltage Quality Monitoring

  1. 1. Voltage Quality Regulation Clean Energy Regulators Initiative Roman Targosz Walter Hulshorst 13 February 2014
  2. 2. Agenda Introduction Voltage Quality aspects Roman Targosz Copperalliance Costs of poor voltage quality Mitigation Measures General guidelines for Voltage Quality Regulation Conclusions | VQ regulation, 2014 Walter Hulshorst DNV GL
  3. 3. Introduction Why voltage quality is important? Difference between reliability and VQ. | Presentation title and date
  4. 4. Power Quality; reasons to address • Energy sector undergoes market transformation. The liberalization of electricity market has brought a risk that quality of electricity supply may deteriorate. Energy regulators have a role to guard this quality. • People in private life but also economy rely on continuous supply of electricity. More renewables or severe weather increase a risk of power blackout. Once the continuous supply is in place there is a concern about quality of this supply. End user equipment has certain immunity to voltage disturbances. This immunity and the performance of supply should create an overlap referred to as compatibility. • The immunity of equipment can be increased as well. The crucial role here would be to define precisely the level of quality which will separate the responsibility. This concept is known as responsibility sharing. The increase in level of detail in IEC 61000 series standard or EN 50160 standard helps. • When the responsibility for end user power quality problems lays a charge on suppliers, the crucial thing will be to solve the equation of how much investment is needed to compensate PQ cost to society. Technical measures are available but the knowledge on level of PQ impact is not satisfatory to move to the optimum societal cost balance point.
  5. 5. QOS COMPONENTS CEER identifies three aspects of Quality of Supply: • Continuity of supply (availability)engineering issue, a function of network design, state of maintenance and investment Partially regulated • Voltage Quality engineering issue, function of network impedance, load distribution and planning Standardised, not regulated • Commercial Quality service response, customer relations, dispute resolution performance, price Regulated
  8. 8. CoS / VQ - changes Continuity of Supply Voltage Quality • Customer is affected by every interruption • • Lack of relibility means costs for • all customers • Power interruptions are mainly caused in the network • Customer is not affected until certain VQ level Different effects for different customers Voltage quality is largely influenced by (other) customers
  9. 9. Reliability / VQ damage functions
  10. 10. Interruption vs. dip UT(r.m.s.) UT(r.m.s.) 100% 100% 40% 0% tf ts tr Illustration of a supply interruption tf – the period of voltage drop; ts – the period with reduced voltage; tr – the period with building up voltage | Presentation title and date 0% t tf ts tr t llustration of voltage dip; run r.m.s. values of voltage by 40% voltage dip; explanation of symbols like in Figure beside
  11. 11. Voltage Quality aspects Technical aspects as defined in EN 50160 | Presentation title and date
  12. 12. EN 50160 – Actors | Presentation title and date
  13. 13. | VQ regulation 2014 up to few secods from 1 µs up to few seconds Transient overvoltages URMS<5% Overvoltages with network frequency Long supply interruption URMS > 5% and < 90 % Plt <= 1 during 95% a week <= 3 min 5% > 3 min Short supply interruption Voltage dip Flicker severity < ± 5 %, and several times during a day < ± 10 % < ± 10 % during 95% of a week -10% Rapid voltage changes Supply voltage variations The nominal voltage (declared) The supply voltage URMS Power Quality disturbances up to the value line-to-line voltage up to 6 kV +10% 100%
  14. 14. EN 50160 Terms Definitions concerning the normal (regular) state of the network operation Network operator – party responsible for operating, ensuring the maintenance of, and if necessary developing, the supply network in a given area and responsible for ensuring the long term ability of the network to meet reasonable demands for electricity supply. Network user – party being supplied by or supplying to an electricity supply network. Nominal voltage Un – is the voltage by which a supply network is designated or identified and to which certain operating characteristics are referred. Supply terminal – point in a public supply network designed as such and contractually fixed, at which electrical energy is exchanged between contractual partners. This point may differ from, for example, the electricity metering point or the point of common coupling. Point of common coupling [PCC abbreviation] – the point on a public power supply network, electrically nearest to a particular load, at which other loads are, or could be, connected. Supply voltage – is the r.m.s. value of the voltage at a given time at supply terminal, measured over a given interval. Declared supply voltage Uc – is the supply voltage Uc agreed by the network operator and the network user. Generally declared supply voltage Uc is the nominal voltage Un but it may be different according to the agreement between network operator and the network user. Reference voltage (for interruptions voltage dips and voltage swells evaluation) – a value specified as the base on which residual voltage, thresholds and other values are expressed in per unit or percentage terms. For the purpose of this standard, the reference voltage is the nominal or declared voltage of the supply system. Frequency of the supply voltage – repetition rate of the fundamental wave of the supply voltage measured over a given interval of time. Nominal frequency – is the nominal value of the frequency of the supply voltage. | Presentation title and date
  15. 15. Normal operating conditions Levels of voltage have been divided as follows: High voltage – voltage whose nominal r.m.s. value is 36 kV<Un<150 kV, Medium voltage – voltage whose nominal r.m.s. value is 1 kV<Un≤36 kV, Low voltage – voltage whose nominal r.m.s. value is Un≤ 1 kV. Because of existing network structures, in some countries the limit between MV and HV can be different. Normal operating condition – operating condition for an electricity network, where load and generation demands are met, system switching operations are made and faults are cleared by an automatic protection system, in the absence of exceptional circumstances, i.e.: • temporary supply arrangement; • in the case of non-compliance of a network user’s installation or equipment with relevant standards or with the technical requirements for connection; • exceptional situations, such as: • exceptional weather conditions and other natural disasters; • third party interference; • acts by public authorities; • industrial actions (subject to legal requirements); • force majeure; • power shortages resulting from external events. | Presentation title and date
  16. 16. Compatibility network operator probability density of immunity of equpment on disturbances (classes of electomagnetic environment 1, 2, 3) immunity level %? e.g. (EN 50160) capital costs in a supply network | Presentation title and date (e.g. EN 61000-3-x, characteristic CBEMA) costs of production of equipment probability density probability density planning level compatibility level and a risk of damage of equipment probability density to adhere the supply parameters network user, manufacturer of equipment
  17. 17. Viaduct – Vehicle Analogy Planning level Compatibility level Equipment immunity level 17
  18. 18. EN 50160 For systems with no synchronous connection to an interconnected system (e.g. supply system on certain islands) For systems with synchronous connection to an interconnected system Duration Duration Parameter 50 Hz ± 1 % during 50 Hz ± 2 % during (i.e. 49,5 Hz ÷ 50,5 Hz) 99,5% (i.e. 49 Hz ÷ 51 Hz) 95% 50 Hz + 4% / -6% of a year during 50 Hz ± 15 % of a week during (i.e. 47 Hz ÷ 52 Hz) 100 % (i.e. 42,5 Hz ÷ 57,5 Hz) 100 % Power frequency voltage Under normal operating conditions excluding the periods with interruptions • Un ± 10 % Supply • | Presentation title and date of the time during each period of one week 95 % of the 10 min mean r.m.s. value; all 10 min mean r.m.s. values of the supply voltage shall be within the range of Un +10% / -15% also for special remote network users • Un + 10% / -15%. Network users should be informed of the conditions. In accordance with relevant product and installation standards, network users’ typically designed to tolerate supply voltages of ±10% of Un. • of the time during each period of one week 95 % of the 10 min mean r.m.s. value ±10% of Un; all 10 min mean r.m.s. values of the supply voltage shall be within the range of Un +10% / 15% 1)
  19. 19. 95 percentile – philosophy of EN 50160 Odered diagram of long term flicker severity Plt 1,60 1,40 1,20 Plt 1,00 ∆ Plt 0,80 0,60 0,40 0,20 0,00 0 100 200 95% | Presentation title and date 300 400 500 600 700 number 10 min measurement over a week 800 900 1000
  20. 20. EN 50160 voltage dips Residual voltage Duration U% ms 10 ≤ t ≤ 200 200< t ≤500 500< t ≤1000 1000< t≤5000 5000<t ≤60000 90 > u ≥ 80 CELL A1 CELL A2 CELL A3 CELL A4 CELL A5 80 > u ≥ 70 CELL B1 CELL B2 CELL B3 CELL B4 CELL B5 70 > u ≥ 40 CELL C1 CELL C2 CELL C3 CELL C4 CELL C5 40 > u ≥ 5 CELL D1 CELL D2 CELL D3 CELL D4 CELL D5 5>u CELL X1 CELL X2 CELL X3 CELL X4 CELL X5 | Presentation title and date
  21. 21. Voltage dips immunity Type II Type I Type III 375 300 Immunity limit on the overvoltages 100 0 Range of tolerated voltage disturbances % Un 200 100 µs 20 ms 10 ms | Presentation title and date Immunity limit on the voltage dips and short supply interruption 1 ms 1 µs t 1s 1min 1hr 1day
  22. 22. EN 50160 – harmonic limits during each period of one week, 95% of the 10 min mean r.m.s. values Odd harmonics Not multiples of 3 Order Relative amplitude Even harmonics Multiples of 3 Order Relative amplitude h h Order h uh uh Relative amplitude uh 5 6,0 % 3 5,0 % 2 2,0 % 7 5,0 % 9 1,5 % 4 1,0 % 11 3,5 % 15 0,5 % 6 … 24 0,5 % 13 3,0 % 21 0,5 % 17 2,0 % 19 1,5 % 23 1,5 % 25 1,5 % | Presentation title and date
  23. 23. Unbalance Under normal operation conditions, during each period of one week, 95% of the 10 min mean r.m.s. values of the negative phase sequence component (fundamental) of the supply voltage shall be within the range 0% to 2% of the positive phase sequence component (fundamental). In this European Standard only values for the negative sequence component are given because this component is the relevant one for the possible interference of appliances connected to the system. In some areas with partly single phase or two phase connected network users’ installations, unbalances up to about 3% at three-phase supply terminal occur. | Presentation title and date
  24. 24. Measurement CLASSES OF MEASUREMENT METHODS ACCORDING TO EN 61000-4-30:2009. Electromagnetic compatibility (EMC), Part 430: Testing and measurement techniques – Power quality measurement methods. For each parameter measured, three classes (A, S and B) are defined. For each class, measurement methods and appropriate performance requirements are included. • Class A • This class is used where precise measurements are necessary, for example for contractual applications, that may require resolving disputes, verifying compliance with standards etc. • Any measurements of a parameter carried out with two different instruments complying with the requirements of class A, when measuring the same signals, well produce matching results within the specified uncertainty for that parameter. • Class S • This class is used for statistical applications such as surveys or power quality assessment, possibly with a limited subset of parameters. Although it uses equivalent intervals of measurement as class A, class S processing requirements are lower. • Class B • This class is defined in order to avoid making many existing instruments designs obsolete. • Class B methods are not recommended for new designs. | Presentation title and date
  25. 25. Costs of poor voltage quality | Presentation title and date
  26. 26. PQ cost summary Dips_and_short_interruptions 100 70 Long_interruptions Labor 63,6 20,97% Harmonics Surges_and_transients 85 28,0% 86,5 28,5% Flicker_unbalance_earthing_and_EMC Process_slowdown Equipment 60 Other_cost Dips 52,5 € bln Short inter. 34 €bln 80 64 21,1% WIP PQ cost in EU >150 bln € 50 PQ cost bln € PQ cost bln € 44,6 14,69% 60 53,4 17,6% 51,2 16,89% 41,3 13,62% 40 37,9 12,5% 36 11,85% 30 40 20 20 10 4,6 1,51% 0 0,2 0,06% Industry 4,1 1,36% 1,5 1,8 1,1 2,1 0,5% 0,6% 0,35% 0,71% 0 0,02% Services Sector 6,4 2,11% 1,3 0,41% 4,2 1,38% 2,9 0,94% 1,4 0,45% 0 Total Industry 3,3 2 0,9 1,08% 0,4 0,1 0,65% 0,28% 0,13% 0,04% Services Sector 3 0,98% 2,2 0,73% Total
  27. 27. PQ cost conclusion from LPQI survey • To arrive at a statistically significant and acceptable model the survey sample was divided into two sub-samples - “Industry” and “Services”. • The cost of wastage caused by poor PQ for EU-25 according to this analysis exceeds €150bn. “Industry” accounts for over 90% of this wastage. • Industry is hardest hit • Dips, short interruptions, surges and transients account for 80-90% of the €150bn financial costs/ wastage • Equipment damage and operational waste (unrecoverable work in progress & underperformance) account for similar proportions of the totals identified • For the most sensitive industrial sectors representing €3,63 trillion (or 20% of EU25 overall turnover) PQ costs amounts about 4% of their turnover. • The apparently insignificant contribution of “Services” to total PQ costs (0,142% of turnover) may result from certain cost underestimation as this sector often experience problems in an office environment where correctly distinguishing between a PQ cause and other root cause may be difficult.
  28. 28. The Cost of PQ and Reliability to the U.S. Economy $Billion 120 100 Total Annual Cost of Power Outages and PQ Disturbances by Business Sector $66.6-135.6 80 60 PQ Disturbance Power Outage $34.9 40 20 Cost of: TOTAL $119 - $188 Billion $14.3 $6.2 0 Digital Economy Continuous Process Mfg. 40% GDP EPRI IntelliGrid Fabrication & Essential Services Other US Industry 60% GDP Source: Primen Study: The Cost of Power Disturbances to Industrial & Digital Economy Companies
  29. 29. Costs from Unmitigated PQ Phenomena EPRI IntelliGrid Study – Average Costs Across All Businesses
  30. 30. Italian Study (2007) about impact of voltage dips on industry • Politecnico di Milano (400 kW - 31 MW): mediana and (mean) • 10.7 €/kW (61.7 €/kW) • • full sample: excl. „0” direct cost: 21.3 €/kW (74.6 €/kW) CESI Ricerca, 2004 (20 kW - 160 MW): mean of PQ disturbances together: 6 €/kW
  31. 31. PQ cost – historical examples (1) T. Andersson and D. Nilsson, in "Test and evaluation of voltage dip immunity," STRI AB and Vatenfall AB 27 Novenber 2002, Sensitivity of different industries to voltage dips expressed in estimated dips cost per industry. The highest position in this ranking is occupied by semiconductor industry which, according to some other sources, experience the highest level of voltage dips cost compared to electricity bill or company turnover of any sector. Different types of industries Textile industry Plastics industry Glass industry Paper industry Steel industry Semiconductor industry €1 000 €10 000 €100 000 €1 000 000 cost [€] €10 000 000
  32. 32. PQ cost – historical examples (3) Voltage dips cost per event based on study carried out in the University of Manchester former UMIST by J. V. Milanovic and N. Jenkins, "Power quality cost for manufacturing industries," presented on EdF workshop in Paris, 2003. Financial losses caused by voltage sags taken from D.Chapman, "The cost of poor power quality," Copper Development Association November 2001 Industry Industry Duration Cost/sag UK steel work 30% For 3.5 cycles £250k US glass plant Less than 1 s $200k US computer centre 2 second $600k US car plant Annual exposure $10M South Africa Annual exposure $3B Typical financial loss per event (€) Semiconductor production 3,800,000 Financial trading 6,000,000 Computer centre 750,000 Telecommunications 30,000 Steel works 350,000 Glass industry 250,000 per hour per minute
  33. 33. The reasons for investigating the cost of poor PQ • Building awareness of the potential magnitude of PQ costs which may largely affect the productivity of the company • While statistics and indicatory values are helpful, no two companies, even when operating in the same sector, will be equally vulnerable to PQ disturbances. Individual surveys are needed • As PQ becomes more and more the subject to contract between a user and a supplier, the cost of PQ needs to be quantified to establish a measure of a value of improved PQ for which the user is going to pay a premium price or receive compensation if PQ is inadequate • In case of failure caused by a PQ event for which the supplier is contractually liable, the amount of compensation will need to be determined. PQ survey will allow a prompt and accurate determination of the amount of PQ loss. • Awareness of the cost of PQ will help to minimise it. Once the PQ cost is known many small and simple incremental improvements are easily justified and possible. • Finally PQ cost knowledge is a tool for regulators to set incentives for suppliers. The benefit should retain for the whole society
  34. 34. Leonardo ENERGY
  35. 35. Leonardo Academy
  36. 36. Thank you | Presentation title and date
  38. 38. Agenda  Introduction  Voltage Quality aspects  Costs of poor voltage quality  Mitigation Measures  General guidelines for Voltage Quality Regulation  Conclusions 39 DNV GL © 2013 13 feb 2014
  39. 39. Mitigation measures (technical) Since most of the power quality problems are cost related this justifies the investments in mitigation technologies by the power company or the customer. A wide range of technology is available to make this possible. In general, technical solutions that increase voltage quality can be at 4 levels: The choice for a mitigation method depends on:  The nature of the disturbance generated and / or to be prevented,  The required level of performance,  The financial consequences of malfunction,  The time required for a return on the investment,  Practices, regulation and limits on disturbance set at the grid operator. 40 DNV GL © 2013 13 feb 2014
  40. 40. Mitigation measures  Premium contracts: – The availability of sophisticated and sensitive net technologies has led customers to demand higher levels of power quality. To meet these needs, some utility companies have set up premium power quality contracts for their customers 41 DNV GL © 2013 13 feb 2014  Labelling: – In most countries Minimum Standards are defined for voltage quality. This anticipates the issue that if a minimum level of quality is met, the customer is not interested in better quality. Some customers need higher quality than the minimum standards.
  41. 41. Guidelines for voltage quality regulation  When setting up a voltage quality regulation framework, there are a number of basic issues that need to be considered first. This understanding is crucial in order to make the right choices in order to arrive at an effective voltage quality regulatory system.  The main issues to be considered during this process are identified: 1. develop a good understanding of what voltage quality is and how it can be measured. 2. clearly defining the objective one would like to pursue with respect to the voltage quality and 3. choosing the appropriate quality control in order to achieve the defined objectives 42 DNV GL © 2013 13 feb 2014
  42. 42. Measuring of voltage quality  The ability to measure voltage quality clearly is a precondition for setting up an effective voltage quality regulatory framework.  But before measuring, of even more importance is the need to clearly define “voltage quality” and develop suitable indicators. Quality measurement is the fundament for any quality regulation system. It is of utmost importance that the data that feeds into the quality control is accurate. These data forms the input of the regulatory process. Clearly, if the underlying data is wrong, so will be the outcome. 43 DNV GL © 2013 13 feb 2014
  43. 43. CEER conclusions on voltage quality monitoring (1)  Voltage quality monitoring are use full tools for regulation: There are sufficient applications with advantages that in the end fall to the network user to justify having a voltage-quality monitoring program. A monitoring program can be fully under the control of the regulator, or, installed and operated by the network operator with the regulator getting access to the data.  Diversification of indices and methods is to be avoided: A number of voltage quality monitoring programs are already in place in different countries. There are large differences between these programs – this makes it difficult to compare the results and exchange knowledge and experience – harmonisation is needed! (choice of monitor locations, types of disturbances monitored, characteristics recorded, indices calculated) 44 DNV GL © 2013 13 feb 2014
  44. 44. CEER conclusions on voltage quality monitoring (2)  Voltage quality monitoring programs should be funded through network tariffs: The most common way of funding such a program is through the network tariffs. This can however vary between countries based on the local tariff structure and regulation.  Making results available is important: Publication of the results (including compliance with voltage quality regulation and important trends) and making data available in other ways are important parts of a voltage-quality monitoring program.  Keep other applications in mind 45 DNV GL © 2013 13 feb 2014
  45. 45. CEER conclusions on voltage quality monitoring (3)  Keep other applications in mind: When setting up a voltage quality monitoring program, it is important to consider all possible applications. Even if the purpose of a program is initially limited, small changes to the set-up of a program or to the kind of parameters recorded or calculated, can allow future applications at no or very small extra effort (setting up of such a program should be done in close cooperation between NRAs and network operators). 46 DNV GL © 2013 13 feb 2014
  46. 46. Define the objective  Once a clear measure of voltage quality has been defined and the relevant indicator to be measured has been identified, the next step is to establish what the quality objective is: 1. the existing level of performance should be quantified and possibly, compared with respect to of international best practice. 2. the quality level that one ideally would like to achieve needs to be defined. Network Costs Interruption Costs Total Social Costs Optimum 47 DNV GL © 2013 13 feb 2014 Quality
  47. 47. Appropriate quality control to achieve the objectives  Once the regulator has identified the appropriate quality indicator, is able to measure it, and has an idea about what performance level should be achieved, the next step is to choose a suitable regulatory control to help achieve that objective.  There is however a second criteria that also need to be taken into account namely whether the quality control can actually be implemented or not. Generally speaking, three types of quality controls can be distinguished: 1. under performance monitoring, the regulator monitors the performance of the network company and where applicable makes this information available to the public. 2. the regulator can apply a minimum standard. Here, a minimum level of performance is prescribed; not meeting this standard leads to a penalty. 3. under a quality incentive scheme, a more continuous relationship between quality performance and financial outcome can be imposed. 48 DNV GL © 2013 13 feb 2014
  48. 48. 1 Performance monitoring  Performance monitoring is relatively simple to implement and requires limited regulatory involvement. The basic idea is to require the network company to report on its voltage quality performance to the regulator.  The regulator can then decide to make this information available to the public  Performance monitoring is the weakest form of quality control as it only provides indirect incentives to the utility. However, it is also the simplest to implement as it requires relatively little effort by the regulator.  Also, in terms of data requirements, performance monitoring can be limited to a number of strategic locations within the network thus eliminating the need for measuring extensively throughout the network or, in the extreme case, at each individual customer connection point. 49 DNV GL © 2013 13 feb 2014
  49. 49. 2 minimum standards  Minimum standards dictate a minimum level to be achieved for a certain performance aspect. In case of not meeting this standard, the utility can be penalized financially or otherwise.  In the case that the regulator aims at increasing performance, minimum standards provide clear guidelines about what quality network operators should aim at.  They set quantitative targets for the companies to achieve. If combined with financial incentives for not meeting the standards, minimum standards can be very effective quality controls.  The minimum standard can be derived directly from standards which are already adopted and used within the power sector industry. For example, in Europe, the European Standard EN 50160 has been generally considered as a reasonable starting point to establish voltage quality regulation systems 50 DNV GL © 2013 13 feb 2014
  50. 50. 3 Incentive scheme  An incentive scheme can be considered as an extended minimum standard. Under a minimum standard, the utility pays a penalty in case it does not meet a certain prescribed level. Under an incentive scheme, a more continuous relation is imposed between price and quality. Each performance level results in a financial incentive, which varies with the gap between actual performance level and the target level.  An incentive scheme extends the minimum standards and makes the financial incentive (being a penalty or a reward) a direct function of actual performance..  Incentive schemes are useful if one is aiming at maintaining existing levels of performance or improve the performance.  But even though theoretically superior, incentive schemes have serious practical limitations: – – 51 it is difficult to exactly measure customer costs due to lack of quality. the collection of adequate and high-quality data. DNV GL © 2013 13 feb 2014
  51. 51. Conclusions  It is crucial that the objectives of quality regulation are clearly defined. This helps to increase the effectiveness of the regulatory system and reduce the risks of adverse effects  The definition of the voltage quality objective follows logically from the perceived difference between current and desired levels of voltage quality. Socio-economic analysis identified the optimal quality level as being a desirable objective.  Three types of quality controls can be distinguished: – Performance monitoring – A minimum standard – An incentive scheme  Typically, the European Standard EN 50160 is used as the basis for setting minimum standards. Where needed, regulators may choose to go beyond the minimum limits imposed by the EN 50160 52 DNV GL © 2013 13 feb 2014
  52. 52. Thanks More information needed? +3126 356 24 32 SAFER, SMARTER, GREENER 53 DNV GL © 2013 13 feb 2014