POWER QUALITY Of Elevators & Escalators

QUALITATIVE ANALYSIS OF ELECTRICAL PARAMETERS Of Elevators & Escalators

INTRODUCTION
The best of the electrical systems , elevators , escalators, moving walkways , even if equipped with the most sophisticated equipment , state of the art technology and the most reliable materials on the market, do not provide the best functionality when not maintained or monitored on a regular basis and by trained personnel. The preventative maintenance is designed to reduce the possibility of accidental failures , extend the operational life of the systems, to ensure continued compliance with the technical specifications of the equipment operation , as well as continuous and full compliance with the legislation .With a more sophisticated reasoning , albeit limited to the management aspects of an electrical installation ( thus omitting all technical and scientific issues ) , there is a clear need in the current market, the containment and reduction of costs and service continuity. It is therefore crucial to know in detail the operation of the electrical system in order to optimize : consumption , load curves, interference of harmonics , voltage disturbances and control of power systems by means of the thermographic analysis etc. . , Ie all elements that contribute to increase efficiency, improve competitiveness and , most significant of these times , reduce harmful emissions into the environment. Finally, in a management viewpoint , the measurement and monitoring of electrical and thermal imaging , allows to optimize the prevention of breakdowns and schedule maintenance thanks to an early identification of problems that, in fact , results in greater protection not only the plants, but the assets associated with them .The subject treated is of primary relevance , since it is closely linked to the so-called " Power Quality " ; known fact sometimes critical situations and disruptions caused by harmonics in electrical systems . It is recalled that the presence of harmonics in the network is indicative of deformation of the current or voltage , which means that the distribution of electricity is done with quality not optimal . In this case, the utilities most sensitive may be subject to malfunctions and the entire system to be called to additional stresses . However, compared to what happened in the recent past , it is not the only industry to suffer , and now the electrical systems in the service sector and in civil society are frequently subject to such "pollution" , with consequences in some cases worse.

MSEE. Ibrahim Gülesin

Predictive maintenance of electrical systems by analyzing Power Quality
The predictive maintenance or maintenance of the condition has the purpose to know in advance the problems of the machines without disturbing the normal operations of the service. The technology of predictive maintenance allows an objective evaluation of the operating conditions of the machine through the application of different diagnostic techniques. The knowledge of the operating conditions of the machine allows you to pre-program maintenance operations , thus having a minimal impact on production and limiting these interventions only to machines that really need it . Requires neither the facilities nor stop the removal of the same and allows the early detection of anomalies is that their severity , providing an estimate of the remaining time of operation and avoiding also the scheduled stops . The benefits arising from the adoption of this maintenance strategy are:Increased plant availability ;Better management of spare parts inventory ;A reduction in emergency response and elimination of salaries extraordinary ;Better security both in operation and maintenance ;A better quality of the product;A reduction in energy consumption;An increase in the useful life of the components;A reduction in the overall cost of maintenance.Predictive maintenance based on actual knowledge of the operating conditions of the machine allows for meticulous planning of actions to be performed , which are limited to machines that really need it , in addition decreases to tend to zero the possibility of catastrophic failures occur and consequently stop of the plants. Predictive maintenance allows significant savings with regard to indirect time costs .
The electricity is probably the main "raw material" for the industry and service sectors. It 'an unusual product because it is required continuously, it can not be stored in significant amounts and can not be subjected to controls that ensure the quality before use. A perfect supply of electricity should ensure continuity of service, within tolerances of voltage and frequency, and have a voltage with a sinusoidal waveform free of distortion. The acceptability of the deviations from the nominal characteristics of the energy depends on the type of use by the user, the equipment installed and its needs. E 'can be summarized into three distinct categories deficiencies of energy quality, understood as deviations from the ideal conditions of supply as indicated in Table 1. Type of disorders, origin and effects.



Each of the problems inherent in the quality of energy is caused by distinct phenomena. Some problems arise from sharing by multiple users of a portion of the supply network . For example , a fault on the network may cause a voltage dip that might involve some users , in numbers proportional to the hierarchical level of the fault itself, or a transient caused by a system user may create inconvenience to all other customers supplied by the same subsystem . Other problems , such as harmonic generation , have their origin in the works of the users themselves and may or may not propagate through the network with consequences against other of the paying customers . The problems related to the generation of harmonics can be stemmed by careful design of the system and tested using filtering systems.The problems relate to the placing of harmonics are often attributable to the user. The cause of the problems on the plant lies in the presence of harmonic currents which , due to the voltage drop across impedance network , generate corresponding harmonic voltages . This voltage distortion , or at least a part thereof, is propagated in plants adjacent to the system and combines with the distortion of the bottom of the voltage present in any transmission system ( for example due to the nonlinearity of the transformers ) . By limiting the emission of harmonic currents , users can bring the level of voltage distortion on the network within acceptable limits.

MSEE. Ibrahim Gülesin

Why detect and limit the harmonics?
Growing phenomenon, only a decade ago the focus on the phenomenon of harmonics was still not heard because the effects on the networks were generally minor. But the use of power electronics has gone increasingly commonplace, greatly amplifying the phenomenon in all sectors of activity and making the crucial need to evaluate the harmonic impact on the plants. Harmonics are more and more difficult to limit since the vital equipment for the company are often the cause of the appearance of the perturbations.

The disturbances caused by harmonics 

• The harmonics circulating in the system causing a general deterioration in the quality of energy and are the cause of many diseases :Network overload (increase in RMS current )
• Overload in neutral conductor due to the sum of the third harmonic currents created by the single-phase loads
• Overload , vibration and premature wear of alternators, transformers, motors
• Wear and overload of the power factor correction capacitors
• Deformation of the supply voltage with a possible malfunction of the users more sensitive Interference with communication lines ( telephone).Neutral conductor , In a three-phase system to star with neutral , the waveform of each phase is shifted by 120 ° so that, when the phases are equally loaded , the neutral current is zero. When the load is not balanced , the current flows only in the neutral balance . 
• Although the current fundamentals elidano , the harmonics do not, in fact, the odd multiple of the third harmonic , or homopolar harmonics , add up in the neutral conductor .
• Skin effect , alternating current tends to be distributed on the outermost surface of a conductor. 
• The skin effect is usually ignored because it has little effect on the frequency, but above 350Hz , which is the seventh harmonic becomes significant , causing additional losses and heating.
• Noise of zero crossings ( zero crossing ) Many electronic converters identify the point at which the supply voltage crosses the time axis to determine the instant of conduction. 
• When there are harmonics or transients on Nutrition, zero crossing becomes more difficult to identify , leading to incorrect operation. In fact , in these particular cases , there can be zero crossings for each half period.
• The effects due to the presence of harmonics , although not instantly visible , can have serious consequences in the medium and long term. These effects are mainly related to an operation of the equipment and components , and supply is the installation of the Client, voltages, currents and frequencies for which they were not powered and because , in general, over- heating (increase of losses reducing the possibility of operating at full load ), increased peak value of the supply voltage , vibration and mechanical fatigue , premature aging of the equipment.In transformers , harmonics , especially those of the current , mainly produce additional losses in the iron and copper .Synchronous motors and asynchronous harmonics cause additional losses in the iron and copper buttons and couples , who may seek improperly organs of mechanical coupling , particularly when the frequency approaches the characteristic frequency of torsional oscillation of the trees.
• The cables are subject to an increase in losses of electrical and copper, in the case of neutral heating cables can be derived from the circulation of harmonic currents of order 3 and multiple .Even capacitors undergo an increase in dielectric loss , but the major problem is posed by the fact that their reactance decreases in direct proportion to the rank of the harmonics , for which the rate of harmonic currents passing through them is much higher than that of distortion of voltage at their extremes .
• It follows that the effective value of a current determined by a distorted voltage is higher than that produced by a sinusoidal voltage having the same effective value of the voltage distorted. Not to overlook is also the possibility of triggering conditions of resonance between the capacitors and the inductive elements of the network, with increases of the currents and harmonic voltages corresponding to the resonance frequency .It also raises the problem of interference on telephone circuits . 
• The devices based on power electronics , as well as being a major contributor in the 110 harmonic generation , are in turn influenced by the presence of harmonics , especially voltage , about synchronization problems and switch ( or diode bridge converters thyristors) .Relatively to the Inter harmonics (at present represent a phenomenon still under study ) , the effects can be due mainly to the origin of the phenomena of flicker , in the case where the frequency is close to the fundamental harmonic Inter .Voltage unbalance , conditions of imbalance can create drawbacks , especially in rotating machines synchronous and asynchronous , because the circulation of currents in the windings of the reverse sequence determines a rotating field of the opposite direction to normal . 
• Then appear in the rotor current frequency of about twice that of the network, causing additional losses , with the following elevations of temperature, reduction of starting torque , noise and vibration.In bridges converters the imbalance of supply voltage causes the appearance eli current harmonics additional , compared to those characteristics .Signals and high-frequency noise , 
• The main systems of signal transmission in Italy used today , on overhead lines for high-voltage transmission with carrier waves , have the frequency band between 80 and 400 kHz .In the cases examined so far disorders should be added that certain sources of high-frequency signals ( HF). These are devices in which the presence thimbles frequencies is intrinsic to the operation (eg . : Telecommunications systems , induction furnaces or microwave , switching power supplies , televisions ), or is a secondary phenomenon , as for the collector engines .
• The effect of HF interference is most easily felt on the occurrence of radio crackles and hums , and on televisions , horizontal stripes unstable , but they can act in a less immediately identifiable on other devices (such as precision instruments and apparatus medical ) .                                     MSEE. Ibrahim Gülesin

ANALYSIS OF THE STATE OF PLANTS 
Electrical systems that are taken into consideration are mainly plants traction elevators / hydraulic, escalators and moving walkways provisti of electric motors, pumps, inverters, etc.. The high utilizzio of these plants makes it particularly interesting tweak of electrical parameters.

For these systems collect on the field the following information: Identification registry machine;Visual inspection;Check current (I) of the absorption line L1, L2, L3, N, Voltage (V) on the line L1, L2, L3, N, Active Power (KW) on L1, L2, L3, N, Frequency (F) ,Reactive Power (Q) and apparent power (S), Power Factor (PF)

Check voltage unbalance / CURRENT, (TANGENT φ), currents, voltages, frequency and average powers Rate harmonic distortion THD, THDV voltage, current THDi up to grade 11Compile tab of the plant;Reports of any non-compliance.Possible solutions based Corrective ActionCheck Temperature - Measure Thermographic.

Used Equipment

The instrument used is the DIRIS60 Socomec and encompasses the whole of the classic series of measuring instruments for electrical parameters. The DIRIS60 among other things permits the measurement of the fundamental parameters of an electric network , such as:

• Current L1 , L2, L3, N,
• Voltages U1 , U2 , U3 , 
• Frequency F ,
• Active power P ,
• Q reactive and apparent S ,
• Power factor PF
• Predictive powers provided
• Imbalance voltage / current ; 
• Tangent cp
• Temperature (optional)
• Current, voltage and frequency averages
• average powers
• Energy meters (Cl. 0.5 S IEC 62053-22 , cl. 2 IEC 62053-22 )
• Pulse Counters 1 * 2 ... 6 ... 6 option 2 option
• ANALYSIS OF QUALITY AND SIGNIFICANT EVENTS Rate harmonic distortion THD 3U , 3V , 3 / In up to grade 63Surges , 
• voltage dips and interruptions , surges
• Storing the RMS curves half period
• Events & AlertsAverage power max KwAverage currents up to
• All these functions can be adjusted to allow for a measurement session that evolves over time , as well as providing the ability to analyze the transient well .

Machine registry identification and verification.
In the following chapter we will discuss the possible areas of intervention that can be easily identified during the preliminary energy analysis, which turns out to be the heart of our business checks. As a preliminary analysis, in particular, to be closer to the issues related to the efficiency and therefore energy savings, has turned attention to the n ° 300 Elevators, Escalators, Moving Walks and Funicular whose operation is continuous during the 'work activities (high number of hours of work per year), with power consumption and easy to calculate and with the possibility to measure the electrical data without disrupting the operation of the same. The evaluation has focused mainly on the study and then electric motors of elevators, escalators and moving walkways.







The THD ( Total Harmonic Distortion) in voltage characterizes the distortion of the waveform of the voltage. If the index value is less than 5 %, which is considered normal , it is not necessary to take any action. If its value is between 5 and 8% , means that the plant is characterized by a strong harmonic and likely there are malfunctions in the plant. If the value exceeds 8% , you need to take action ( clearing systems ) to prevent malfunction.The THD ( Total Harmonic Distortion) in current characterizes the distortion of the waveform of the current. If its value is less than 10% was within the normal , but if it is between 10 and 50% means that it is in the presence of a plant with a sensitive harmonicity that could cause overheating : may be necessary to oversizing of the conductors. If the THD in current is greater than 50% are in the presence of a strongly perturbed system malfunctions that may have significant : it is necessary to undertake an analysis of the system to make the appropriate countermeasures .

MSEE.Ibrahim GULESIN

WHY ' INSTALL HARMONIC FILTERS 
The economic influence related to the presence of harmonics can be summarized as follows :Increase in losses - the presence of additional losses of energy obviously weighs on installation costs , including the possibility of having to sign contracts with more onerous or otherwise penalizing rates , as happens in some countries ;Need for oversizing - the need of having to oversize conductors and electrical equipment can be an additional burden not indifferent ;Costs of plant stop any additional costs resulting from untimely intervention of protections ;Decreased life span of materials - as a guideline, a study by the Canadian ElectricalAssociation showed that a supply voltage with THD of 10% causes a decreaseof life :32.5 % for single-phase devicesof 18% for three-phase5% for transformersTo have the equipment that ensure the lifetime required must resort , once again , the excessive .

Criteria for selection of filters to be installed.
passive filters allow :the reactive power compensationa large filtering capacity in current.The system on which to install a passive filter must have sufficient stability with load fluctuations limited.If the reactive power supplied is important is advisable to disconnect the passive filter for the periods of reduced load .The connection diagram of a filter must take into account the presence of a power factor correction capacitor that may be required for its disconnection.active filters allow filtering of harmonics over a wide frequency range with acompensation very precise . Are suitable for any type of load , however, the power that they are able to provide is limitedthe hybrid filters combine the performance and benefits of passive filters and active filters . The absorption filters harmonics are used in industrial applications , together with invertervariable frequency converters equipped with a six-pulse , when it is in the presence of a loadalmost predictable , such as escalators , moving walkways , elevators. The components of the filters are tuned in such a way as to absorb only the harmonics more problems and offer very low impedance at all other frequencies . For this reason they have low losses . They are essentially passive filters based on the series / parallel connection of capacitors and inductors . They are connected to the line side power input of an inverter. At full load, the total harmonic distortion can be reduced up to the value of 5%. also additional benefits that can be obtained with the use of absorption filtersharmonics :Elimination of interferences due to switchingReduction of energy consumptionIncreased service life of the inverter and the motorImprovement of power qualityImprovement of the displacement power factor ( PF )Improvement dell'harmonic power factor (PF )The absorption filters harmonics can be used with electrical loads that have distortionharmonic constant and predictable with one or two predominant harmonic frequencies such asfifth and seventh ( 250 Hz and 350 Hz) . A single harmonic absorption filter can be used with several inverters as long as the inverter partano and shut down simultaneously and not sequentially.

EXAMPLES OF APPLICATIONS: 
The figures show a typical application of harmonic filters to the escalator, geared and gearless elevators. MRLs that are driven by an induction motor or synchronous AM and is used in public and private buildings. The filters are designed to reduce harmonics in accordance with the Lift Directive 95/16/EC laying down, a manufacturer may apply harmonized standards in order to meet the essential requirements of the EMC: EN 12016:2004 - Immunity EN 12015 2004 - emissions (including tables for limits RFI and harmonic distortion).

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