Villamosságtan | Felsőoktatás » Energia megtakarítás előadás, angolul

E Energy audit dit What is it mean? Wh iis it necessary? Why ? What is the target? g What type of organisations need for it? What type of tools need for it? Energy audit • The energy audit Th dit could ld be b a project j t which hi h ttargett is i to t clear l up and d evaluate l t the th situation of energy usage of a given object , most of the case productional companies, offices, hospitals, buildings etc. • It must be organise because energy is not a unlimited source, necessary design with it. Possible causes: • – – – – – Local organisation request for his owen targets or solving his problems. If there was some problem in the electrical network, and couldn’t clear up the reason, that case we were asked. Decison of goverments or directions of multinational companies. Offer of service companies looking for good business opportunities Etc. We can suppose , for this time there was no interesting these exemined things, so most of teh case there are some

problem problem. Target of energy audit • The ttargets Th t are saving i energy during d i the th operation ti off the th object bj t , and d impove i the th energy usage. • We have to save energy that way that production or operation quality of the object couldn’t be worst. • We could improve the energy usage if we improve the energy quality and the application technology: – – – More efficient technologies More efficient machines or devices The using customs (human side) The organisation of a energy audit • • • • • • • The energy audit Th dit is i a project. j t It can perform f by b people l from f different diff t profession who has knowledges or practices in energy usage. Necessary a specialist who has knowledge in architect, specially in building isolation. A mechanical who has practice in technology and machines machines. Electrical who has practice in electrical energy usage and electrical machines and devices. Necessary a leader man

who organise the activities, activities and he has a avarage knowledge about the different professions. Etc. This is a special project , it is rare situation when all of these professionals exist at the targeted company and could afford energy to this task. This could be the profile of a project p j company. p y The tools of the energy audit • • • The biggest Th bi t activity ti it iis gathering th i d datas t ffrom th the objet bj t llooking ki th the diff differentt places, l devices, or examinate them. We have no photos, because most of the companies don’t permit making photos because of technological secrets. Every specialist has to know what kind of testing device he need . This is not too much. For electrical tests we need network analysator, current clamp with power meter, voltmeter and tools to remove covers from the devices and reinstall them. To the last is better if there is a local electrical, who has special tools and knowledge of the local rules. Very

usefull if the project company has a special software to evaluate the different datas, and could make a visualisation. Information requirment to be gathered • • • • • • • • • • Only O l the th electrical l t i l side: id The activity and technology of the object. The annual used electrical energy. The requested energy in the contract. The electrical network scheme. The technology or activities of sub systems of the object. The result of measured datas by network analyser of the total energy consumption .and measured datas of the biggest energy consumers All available datas of the used machines . M Measured d powers, voltages, lt power factors, f t harmonics h i off the th mostt important. i t t machines and devices. Experiences from local people of the behavior of machines and devices. Typical problems of industrial facilities • • • • • • • • • • • The mos important problem, problem there is no responsible person for energy usage

usage. They don’t know the energy usage, so they make wrong energy contracts. They lost a huge money. No permissions to stop production for maintenance. Lack of regular maintenance. They have old devices, nobody know how they work, no datas. No information about their effciency No data tables on the motors, transformers. Serious modifications of the power network and no documents about them them. They could have problems from unknowen reasons. Most of the case a longterm measuring by network analyser helps clearing up. Wrong gp power factor. There could be a lot of reason Not confortable electrical workplaces. Cubicles are outside, in the corridors, in dirty places. Difficult to check the networks, so maintenance is difficult too Overloaded cables, busbars T low Too l or too t high hi h voltage lt att th the b busbar b or att th the d devices. i The voltage is not stable. The current is unbalanced. This is important for capacitor for banks , protections etc Typical yp problems of

industrial facilities p • • • • • • • • • The voltage Th lt is i unbalanced. b l d It iis problem bl off motors. t The enviromental conditions are not good for electrical devices. Temperature could be too high , too low ,dusty places etc. (contactors, semiconductor devices) Old electrical cubicles with no safety circuit breakers breakers, fuses blocks blocks. Wrong earthing or neutral. Could be a lot of harmonics, and cable traces are wrong installed. O l d d or underloaded Overloaded d l d d iinputt ffeeding di ttransformers. f Overloaded devices. Defective devices. U ffi i t d Unefficient devices i Electrical system check • • • Check the input cables, the input power Take a visual check. Measure the consumed energy properties for a longer term by network analyser and evalute: – – – – – – • • • Tuch the isolation of cables. Are they warm? You can take a look to the safety, like earthing, isolating etc. Check the transformers – –

– – – • The voltage values and balancing The current values and balancing The real p power . The relation with the contract The values in the active and inactive times The reactive power. Is the power factor correction good? The energy measuring devices. The harmfull harmonics, specially at the neutral. Is it sized well? Is there paralell operation? Measure the voltage.(value and unbalancing) Is there automatic switch over system? Whre is measured the energy consuption? If at the primary side, we can measure by analyser the secondary side. So we could calculate efficiency Ch k th Check the sub b di distrubutors t b t – – – – – Is the voltage drop not too much? Is the cable cross section good? Could be worthy a local power factor compensation? Voltage unbalance is not high? Current unbalance? Electrical system y check • C Check ec tthe e de devices, ces, machines ac es • Check the lighting and lamps – Are A th they clean? l ? – Have they energy

effective lamps? Is it worthy to replace them by another ones? – Are theyy lighting g g in uneffective times? Is it worthy a automatick switching on-off solution? – The number of them is good? • Check the computers – What is their working g hours at the day? y – Have they energy efficient power supplies? – When they are out of work they are switced off or stand-by? • Check Ch k th the motors t – – – – – – – – – – – Do you see any mechanical problems at the motors? Do they have data tables? Is their connection good? Current unbalance less than 10% Th i enviroment Their i t iis acceptable? t bl ? Is their technology energy efficient?It could be worthy speed driver? Has they regular maintenance? What is their ages? What is their running hours in a year? What is their energy consumption? Have they any datas to evaluate? Specially energy efficiency. Electrical system y check • Motor checking – – – • Ch k the Check th power

electronic l t i d devices: i – – – – – – – – – – • Check the currents , voltages, g , aktive and reaktive p powers. If is it not p possible,, because of short connection wires, check at the feeding cubicle. (a lot of energy saving possibility) Check the cooling. Check their mechanical properties. Check the UPS. Its efficiency is the best Is his operating type good? It could be worthy a off-line type or generator? Is it necessary that power? Every devices which are feed by it need this type of energy? The enviromental conditions are good? (temperature, dust) Its operational p conditions are g good?(( g good batteries, balanced output p current)) Check the motor speed drivers Are they good sized? Is their energy efficiency good? Are they set corretly?( 10% energy saving) Check the confort machines, like cafe automats, kitchen machines, etc. – Are they switced off in out of working hours? Energy quality • • Main parameters in energy quality, we must

think: Voltage is too high high. – • Voltage too low. – • The motors efficiency will be worse . Their life time decrease Power factor is too low. – – • The motor efficiency will be worse . The electronic devices use more current current, the cable losses rise. Voltage unbalance. – • The lighting devices, heaters will using more power than necessary. It is necessary paying charge. The feeding cable current will be higher , may be twoo times higher then available. Power factor is too high or capacitive – – – – If there are few of big power motors, their contactor could burn down. There is high equivalisation current betweem the motors and capacitors . If th there are h harmonic i current, t th the voltage lt vill ill be b very di distorted t t d and d his hi effective ff ti value l will ill increase. If we switch off from the transformer , overvoltage will arise. Energy quality • Current unbalance – Where are set the protections ? To the

highest current wire? The lowest current wire is protected well? – How does work the power factor compensation. It compensate simmetrically – One phase compelsated well, the other under or over compensated? – Are the wires overloaded? – The solution is balancing the currents by changing the phases on the cables. ( – (Explanation of it in the blackboard) Energy quality • Harmonics – – – – Heats the motors and decrease their energy efficiency. Destroy the capacitor banks. Disturb or destroy the sensitive electronic devices devices. Could cause very high neutral current. The neutral busbar could be overloaded. – Ca Cannot ot co compensate pe sate well, e , because tthe e harmonics a o cs has as reactive eact e component too and the capacitors compensate only the ground frequency. – (explanation) • I Inrush h current. t – Cause voltage drop. May be the contactors switches off, the motors stops. The UPS go autonomy without any reason and send alarmThe

lamps blinks. – Necessary higher protection value . May be it has to oversize the circuit breakers and busbars. – Necessary special starter circuit Energy quality • Voltage V lt drops d – The lamps blinks – The electronic devices switces of – The circuit breakers switch off and mayy be the technology stops.(Coulob be huge damages) • Voltage rises – The electronic devices could be damage. – The lamps blinks, blinks may be burns down down. – Some of electrical devices could burn down. Reason of the bad energy gy q quality y • • • • • • • • • • One of the reasons could be the week electrical network of the suplier. If he has long cable network at low voltage, may be there are lot of voltage drops or voltage lt is i ttoo low. l If he has not safety network, there could be a lot of voltage break. This values could be nominate, if we connect a constant network analyser to the network. network At the user side could be high power motors with

high starting currents. This cause inrush currents and voltage drops. Necessary well sized circuit or softstarter or speed driver driver. Voltage disbalance could arise from bad installation, unbalanced loads. This causes heating the motors and decrease their efficiency. Could cause of damage of speed drivers and UPS’s UPS s Wrong power factor exist when no power factor correction or it is faulty. May be wrog sized. There are too large capacitor steps, the bank is low etc May be wrong setting. Reason of the bad energy gy quality q y • • Harmonics could arise from nonlinear loads. This could be different types of non heated fiber lamps, LED lamps. Electronic devices like computers and accesories, home electric devices (TV) UPS Motor speed drivers. When the motors and drivers are oversized, this could be higher When the power factor is compensated to 1 and there are harmonics, the system amplify the harmonic currents to a dangerous level. The voltage harmonics will be high if

there are current harmonics and the network is weak. k The speed drivers are not filtered. The DC speed drivers creates very large harmonics, especially they are underloaded (explain). The new AC motor speed drivers are compensated for harmonics. Reason of the bad energy gy quality q y • • • • Inrush current When a motor starts its starting current 3-12times of the nominal current. Normally it is some periods, but at a heavy loaded motor it could be 10-20 sec. We can decrease this current by softstarter to the 3-5times nominal current. By speed driver we can start the motor by less then nominal current value. The older electronic devices could arise inrush currents, but it is not too high. Using network analyser • • • • The user manual Some result of measured values in the file map: Telephelyek (Detailed explanation) Calculation of energy losses due to bad energy quality • Voltage V lt di disbalance b l C Cannot t calculate. l l t Depend D d on the th

motor t b behavior, h i which hi h possible measure a a appropriate laboratory. One cause is taht harmonics creates heating, the second, the phase shifting will be not exactly 120 degree and the rotatied magnetic field distorts. • • • Power factor We have to count the compensated current and badly compensated current . The nominal diference of them multiply by the square of the cable resistance and multiply by 3, because there are 3 wires, gives the dissipated power in the cable. Energy loss calculation at wrong power factor Calculation of energy losses due to bad energy quality • • • • • Harmonics H i At the neutral of the cable we can calculate harmonics by same way: 2 P(loss)= I(harm) x R (neutral wire) It necessary to calculated for all harmics and add. Measuring is more simple. At the motor is difficult , because not only dont gives rotation energy to the stator, may be breaks itit. We can approximatee , less than 1% Let see the speed driver output ,

the voltage is rectangular, but the power loss less than 1%. Calculation of energy losses due to bad energy quality • • • • • IInrush h currentt At the motors is it possible to calculate, but there is a simple practice: I checked a Dahlander motor which drived a drill. Power 4 kW It has drilled every 3-4 minut 1 hole hole. I measured the energy for 1 1-2 2 weeks. weeks I installed a speed driver to the motor, and measured the energy consumption. That case no inrush current The rewarding time of the speed driver was between 1-2 years. I can say , depend on the application application. The high power speed drivers and UPS’s dont like their inrush current. It is better eloctronicalli start and stop only, and not by power switc on and off. The effect of the inrush current , the technolgy stops because voltage drops, could be expensive. Calculation of energy losses due to bad energy quality • • • • Nott nominal N i l voltage lt The effect ot higher voltage

tan nominal to most of the lamps, They consume higher power . May be the light is higher, but we don’t need it Moreover the lifetime will be shorter At the motors is not problem between the permitted limits ,to shorter.At to their efficiency has not a big influence. To the electronic devices between the permitted limits no influence, they regulate their input power. If the voltage g outside the p permitted limits,, no q quaranty y of harmless to the devices. At lower voltage the current of the motors will rise . The cuper loss will rise too, and the losses at athe cables will rise too. Ways handling the energy quality problems • • • • • • • Managing M i th the h harmonics i There exist active harmoic filters , which can set back the normal sinus wave voltages and currents. Theyr price is so high , that not worthy dealing with them Moreover they use energy too and they need coolig . The other way, the harmonic generator devices possible to replace by a new ones,

or, for example to the speed driver possible to connect anti harmonic filters. The new devices g generates less harmonics. When the problem is big, possible to create a dirty and a clean networks supplied by separated transformers. Fit the motors and speed driver power to the driven thechnology , A loaded speed driver generates less harmonics. To the capacitor banks necessary to install anti harmonic filters, protect them from harmfull effects. To protect the electronic devices , correctly follow the installation standards and factory descriptions. Ways handling the energy quality problems • Voltage unbalance • • This is not a normal condition. It must looking for the cause of the fault and repair it gy supervisor p system y is a good g tool to find the cause this kind of faults. The energy Ways handling the energy quality problems • • IImproving i th the power ffactor t iis a simple i l b butt nott a cheap h thi thing. We have to know by measurement the maximun

reactive power and the regulating steps. It is symple measuring by network analyser We have to know the voltage and current harmonics in the network network. The manufacturers makes different types of capacitor banks for differently distorted network. It is good, because decrease the necessary feeding current so may be we can buy cheaper the energy. It could be assembling locally, it is cheaper , but the main advantage, we can better fit the capacitor values to the application. Transformer check check. • • • • • • Checking Ch ki th the ttransformer f iis possible ibl only l when h th there are iinstalled t ll d tto th the primery i and d secondary side: voltage and current transformers and power measuring device. At the primery side there is high voltage, no possible tuching it, and at the secondary side there are large crossection cables cables, difficult to find power measuring device device. It exists. Simple way we can check only the secondary side, the voltages,

may be currents , powers and harmonic. p Is it possible to connect to the primery side 400V, but take into account , its behavior is not exactly linear. The best way to believe to the data plate, and compare it with a new one. The transformer consumes reactive energy too. The manufacturers could say how much kVAR necessary to the low voltage side . Practically 630 kVA need 25 kVAR Motor check • • • The mostt importatant Th i t t t sources off the th electrical l t i l losses l in i th the motors t th the copper lloss iin the windings and eddy current in the rotor . Moreover mechanical losses of the bearings. At th enew motors, motors according to the IE1 and IE2 prescriptions in Europe , there are bigger crossection of windings and the rotor is made from better material. The efficiency is by 5-10% higher then the previous ones. Replace them is a good investment it comes back in 1 year. In the installed situation is not easy measuring the efficiency, i don’t suggest it .

Very difficult measuring the mechanical power on the axis. I suggest a cheaper way: measure the electrical input power of a built in motor . Buy a new European motor with same nominal power. power IE2 is more expensive than IE1 IE1, but the efficiency is higher. Replace the old motor by a new one and now measure the input electrical power. The old motors came almost from same family p y and the new ones too. The measured values by such way can be extrapolate to the other old motors. • This is a engineering appriximation. Calculating the energy losses • • • We have W h tto maesure th the power llosses We have to approximate the the working ratio in a year . For example a motor works for 8 hours a day and usefull time is only 2 hours, You could calculate loosing the power 6 hour a day, day and there is 240 workday a year year. The loosed power this case could be 240x6 hour in a year. If we multiply it by empty motor’s power and the price of a kWhour energy we can get the

price of the wasted energy.This could be equal with the p price of a speed p driver whic can solve this p problem. • The calculation could be same if we use bad efficiency lamps . We have to calculate the working hour of the lamp in a year and multiply by the power difference between the good and bad efficiency lamps. • I never tried counting difficult schemas . Measured the datas, calculated or extrapolated with them symply. Available thechnolgies to improve efficiency of motors • • • • • When we h Wh have a good d motor t , it is i advisable d i bl to t perform f the th regular l maintenance. i t Necessary to check the electrical parameters, and doing steps if anything is not good. Replace bearing when the manufacturer offer. Install soft starter if it starts heavily, or the power is high. Install speed driver to the pumps and fans if the delivered quantity of materials was regulated by valves. Uninstall the valve and regulate the motor speed The investment

comes back in one year year. Choice of the motor types • • • • • There are different types of motors : Synchronous motors DC motors Slip ring motors Tri phase shorted cage asynchronous motor etc etc. • My former firm the Schneider Electric 20 years before manufactured drives for all types of motors, but the world market asked only the tree phase shorted cages asynchronous speed drivers. The customers know what is the best for them For special cases there are dc motors, like tools , high speed rotation. Everybody y y short the slip p rings g at the slip p ring g motors and drives by y asynchron y motor speed driver his motors. • • F Frequency konverters k t and d soft ft starters t t • • • • • • • • • The softstarters Th ft t t They can start the heavy starting loaded motors . The former solution , the star delta could start only the unloaded motors. It can limit the starting current . It is importamt when the available energy is limited

limited It can limit the starting torque. It is important at the pumps, feeding old tubes(water hammer effect) At the big motors the starting rate in one hour is limited. limited By softstarter it is possible increasing it. The softstarter is a coplete motor protection. The softstarter is a measuring device , it writes the datas to the display and can communicate digitally. The softstarter has good efficiency, because it is shortciruit when the motor run. It is not very expensive compairing by star delta starters. F Frequency converters t and d soft ft starters t t • • • • • • • Frequency converters F t They most important task regulate the speed of a asynchronous motor such way that alter the frequency of the tree phase voltage which connect to the motor and drive it. It can accelerate the motor with a starting current which most of the case less than the niminal current. It can turn the motor in higher frequency than its nominal speed, for example 5000 turn/min In

the technology they save energy. At the pumps and fans they do it There are speed drivers for cranes, which pumps back the breaking energy to the mains and theyy use byy 40-50% % less energy gy than usual crane application. pp There is application, when not necessary feeding always same quantity of water. It solved by speed driver and we can win 80 % of energy. Energy Supervisor system • • • The advantages Th d t off th the energy saving i th thecnologies, l i d devices i could ld change. h Necessary always checking them, how they work? For example we break up a energy saving technology because of emergency. The temporally cases will be constant things, may be we don’t don t improve the bad speed driver. If we dont sense the losses, don’t care with them. There could be some energy wasting device or technology which possible clar up by continous measurements. For these problems is a good way to install energy supervisor system H How to t b build ild up a energy

supervisor i system? t ? • • • • Necessary a countinously N ti l running i software ft on a computer t , which hi h always l asks k d datas t from the measuring devices on the site. This software aggregate the datas , stores them (to a SQL server), and when necessary , call back and set to human friendly format , it creates graphs. It is possible evaluating , because we can see the behavior of powers , currents, voltages etc. behaviors for the desired time period This software has to be high power, because the data quantity could be very high. The asked device number could be high too. This software is the Power Logic software of S h id El Schneider Electric. ti Necessary measuring devices to the important points of the technology . They have to communicate by the computer, and they have to measure the desired parameters. They have to very good quality quality. Cannot appear the question: this is real data or faulty device data? Necessary a communication network too . This

could be a symple modbus network, but could be necessaryy modbus –TCP g gateways y and switches too. And necessary a professional man who can handle this system, and responsible for the energy saving. H How can calculate l l t with ith energy supervisor i system? t ? • • • • • • This iis nott a cheap Thi h system. t In Hungary there are installed more hundred of them. The avarage energy saving could be more than 10% There are cases where this is 80%. There are cases where we can’t count it , because the technology always used it. There are cases where there was installed only for energy quality problem. Oth advantages Other d t off the th energy supervisor i system t • • • • • • • The main Th i ttask k off th them ffacilytate il t t th the energy saving i and dd decrease th the energy quality lit problems. They contains SCADA systems too . It visualitates the technology in a computer display It could be very usefull when the area is big display.

big. We can switching with them and regulate the technology from distance. We can sharing energy costs between different users. We can allocate with them energy costs to the different technologies and products products. We can set different alarms and supervise the technologies. The others in the word documents. S Some pictures i t off energy supervisor i system t •