AKGEC INTERNATIONAL JOURNAL OF TECHNOLOGY, Vol. 4, No. 1 Dimensions of Efficient Use of Electrical Power in CPRI Dr. I.P.S. Paul G-1, R-8/9, Krishna Residency, Raj Nagar, Ghaziabad 201 002 UP. paulcpri@yahoo.co.in Abstract -- Energy conservation which once was considered as an option to increase the profitability has become a necessity now to offer equal level playing with global competitors and stay on the race. This paper projects Central Power Research Institute s initiatives through technology driven services for empowering creative and productive decisions. Bangalore is a blessed city from the consideration of moderate weather conditions and therefore the energy consumption for buildings is accordingly very low. Lighting which can result in 1.2-2.0 % energy savings (3.75-6.25 kwh/month), and energy saving controllers in air conditioners can result in saving of 0.4 % of the energy consumption (1.2 MWh/month). The presently available meters are inadequate to completely cover the network in the whole Central Research and Testing Laboratories, Bangalore campus with an actual demand. To monitor and control energy consumption at various laboratory /divisions/sections reliable metering at key points is required. The study of the electrical network indicates that lab equipment and network account for nearly 47 % and 27 % of the energy consumption. Keywords: Efficient use of Electric energy, Energy audit, Building audit, Energy meter audit I. INTRODUCTION ELECTRICAL energy is the most important form of energy in practice today. Energy Audit is an analytical method of detection of energy wastage and misuse. It is similar to the monthly accounts statements in financial accounts system. It is a part of the action step - a detailed analysis of the aspects of energy cost or suboptimal usage, together with proposed solution and monitoring. The energy audit is thus the process of collection and analysis of data on present energy use, choice of energy management and the processes used to monitor progress towards those objectives. Energy audit indicates where the consumer stands from the energy utilization point of view, and where he wants to proceed to. The objective of energy audit is to reduce energy consumption for the same level of production. The energy audit serves to identify energy stream into a facility and to quantify energy use according to discrete functions. Energy audit alone does not provide the answer to the important losses and therefore identifies the major area, where management effort should be concentrated. An energy audit identifies the cost of energy and where and how it is used. It provides a base from which results can be measured and from which the programmes can be further developed [2]. Steps involved in an energy audit program are: Measurement and recording the amount of Electrical energy consumed during a particular period or interval chosen. Close observation of utilization in various separate areas like lighting, heating, air conditioning, drives etc. II. ENERGY AUDIT IN CPRI Central Power Research Institute, Bangalore as an organization is in the forefront of power research and testing. Most of the energy is used for research and testing purposes. The average energy consumption is about 2.5-3.0 lakh units per month with the monthly bill about Rs. 18 lakhs. As this is a large amount and a need has been felt to reduce power bill and energy consumed to the extent possible. [5]. The task of energy audit at the CRTL complex has been divided into three sections. Energy meter audit Lighting & Building energy audit Energy audit of an electrical network CPRI has two feeders to supply power to the various facilities: One 220 KV feeder One 11 KV feeder. The operational philosophy in practice at the institute is to ensure reliable power supply to various locations so that the 220 KV feeder is charged always and the 11 KV feeder is charged occasionally during maintenance in 220 KV feeder / holidays [6]. The contract demand is as follows : 220 KV feeder : 3,500 kva 11 KV feeder : 350 kva. The basic energy details of CRTL campus are as follows : Contract demand : 3500 KVA 42
EFFICIENT USE OF ELECTRICAL POWER Monthly energy consumption : ~ 3 lakh kwh/ month Annual energy consumption : ~3.6-4.0 million kwh / year Monthly energy bill : Rs. ~18 lakhs Power factor : > 0.95. Electrical energy is consumed in the various divisions for both core testing, research activity and office use. This energy is accounted under various divisions. Monitoring methodology High energy consuming labs are monitored on daily basis by high power Engineers. Medium and low energy consuming labs are monitored on weekly basis. Total units consumption and revenue earned are studied on monthly basis. Energy meters are installed at locations for monthly consumption analysis. [2] III. ENERGY METER AUDIT For audit of the metering solution for CRTL campus, the presently available meters are given below: 2 meters of BESCOM (220 KV & 11KV incoming lines) 13 programmable static tri vector meters in substation 36 static watt-hour meters in various locations Meters installed : The total number of meters installed is as follows : S.N. Particulars Detail Quantity 1 BESCOM meters 220 KV 1 S/S 11KV S/S 1 2 Trivector meters 33 KV S/S 10 11 KV S/S 3 3 Static watt-hour meters Direct 12 (in labs /offices) with CTs 29 4 Total no. of meters 56 A total metering solution of the CPRI, CRTL office complex would involve continuation of the present meters, adding new meters and replacing faulty ones. Continuation of meters in good working conditions: The meters to be continued are as follows: S.N. Particulars Detail Quantity 1 BESCOM meters 220 KV, 11 KV S/S 2 2 Trivector meters 33KV, 11 KV S/S 13 3 Static watt-hour meters with CTs 29 4 Total no. of meters 44 Additional meters required: S.N. Particulars of new meter required Quantity 1 Bifurcation of meters to segregate 22 energy consumption of labs/buildings 2 Replacement of non-functional meters 4 3 Replacement of meters giving erroneous reading 2 4 Replacement of direct meters with 12 meters connected to CTs/PTs 5 Meters to cover areas not cover presently 18 6 Maintenance spare meters 12 7 Total requirement of new meters 70 8 Meters provided by department 20 9 Total requirement of new meters 50 IV. LIGHTING AND BUILDING ENERGY AUDIT Lighting audit:the estimated share of energy consumption for lighting in India is 17 % as compared to 7-8% in developed countries. The lighting sector hence offers significant energy saving opportunities. The lighting load is ~90 KW and the monthly energy consumption is 27 MWh/month or nearly 9% of the CPRI energy consumption. This is a reasonably low figure as compared to other places but there is scope for reduction to 5 % of the CPRI energy consumption or below by energy conservation measures. Energy can be conserved by the following : Optimal use of day lighting Use of lamps of high luminous efficiency High luminaire efficiency Periodic maintenance schedules Achieving high reflectance in rooms. Efficiency of lamps and luminaries: The performance of indoor lamps under standard conditions is given in Table 1 [3]. It can be observed that compact fluorescent lamps (CFLs) are inherently superior to tubular fluorescent lamps (TFLs) and incandescent lamps (also called as general service lighting 43
AKGEC INTERNATIONAL JOURNAL OF TECHNOLOGY, Vol. 4, No. 1 GSLs) are the least efficient. However, GSLs give steady lux levels GSLs are not seen in any lab/office of CPRI. The illumination efficiency is 6.25 lux/w at 230V for CFLs. The recorded lux/w levels in the present study are higher because of the effect of day lighting. Table 2 gives a comparison of the performance of commonly used outdoor lamps under standard conditions [3]. It is seen that high pressure sodium vapor (HPSV) are inherently brighter as well as more efficient than high pressure mercury vapor (HPMV) and metal halide (MH) lamps. Even though TFLs and even GSLs are used for outdoor road lights, these are inappropriate and must be gradually replaced by HPSV lamps. The luminous efficiency of the TFLs with electronic ballasts is inherently superior to those with conventional ballasts but the lux levels are only 80-95% of the latter. Also, the electrical quality (harmonics and power factor) can not be ignored. Power factor above 0.85 and total harmonic distortion below 5% are an essential requirement [4]. The luminous efficiency and ratings of the lamps for indoor and outdoor lighting are given in Table 3 & 4. The lamps for indoor lighting focus on CRI & efficiency while those for outdoor lighting focus more on lux levels and efficiency. As per Indian Standards the luminous efficiency of GSLs should not be below 12.5 lumen/w at 230V for lamps of 40-200 W. For TFLs and CFLs the luminous efficiency should not be below 56-60 lumen/w for TFLs of 20-65 W and CFLs of 16-23 W. Apart from improving the lamp efficiency, the optical performance efficiency of the luminaire must also be improved. Luminaire efficiency is an important criterion in gauging the energy efficiency of a luminaire. The luminaire efficiency of standard luminaries is around 60%. That of high performance luminaries is around 80-85%. Luminaire efficiency is different from utilization factor, which is the product of the room utilization factor and the luminaire efficiency. The color temperature of majority of the lamps at CPRI is around 6500 K and hence very good. The color rendering index is almost 1 and the glare is also very low. Light reflection in a room is also a significant parameter. Good reflectors (reflectance > 60%) such as white paint/paper, silvered mirrors, polished marble and glazed tiles enhance lux levels. Poor reflectors (reflectance <25%) such as red bricks, granite and brown/red paint reduce the lux level (Table 5). TABLE 1: PERFORMANCE OF INDOOR LAMPS TABLE 2: PERFORMANCE OF OUTDOOR LAMPS 44
EFFICIENT USE OF ELECTRICAL POWER TABLE 3: LAMPS FOR INDOOR USE TABLE 4: LAMPS FOR OUTDOOR USE TABLE 5: REFLECTIVITY OF SOME OF THE COMMONLY USED WALL MATERIALS The suggested measures for Central Research & Testing Laboratories complex are as follows: I. Replacement of 40 W tube light (standard FTL) with either mirror optic high lumen tube light (36 W) or with electronic ballast or 28 W T5 TFLs. These will improve the lux level substantially, which in turn may improve the working efficiency of the employees because of better working condition. [3] II. Transformation of higher ceiling mounted fittings into suspended ones. III. Increase use of day light in more rooms. Efficient day lighting by providing spacious window area (15-30% of wall area). IV. Use of solar photovoltaic lights for isolated areas. Single lamp stand alone solar photo voltaic lighting systems are recommended for few such locations. Typically 40 W modules can be considered for indoor lighting and 100 W modules can be considered for outdoor lighting. The unit consists of PV module, battery, charge controller and inverter elements. The locations include path/road towards Centre For Collaborative and Advanced Research, peripheral boundary areas near walls. These can be installed in around 10 locations in the CRTL campus. V. Immediate measure : Procurement of 36 watts high lumen tubes (instead of 40 W) for replacement of fused tubes as replacements. VI. In corridors and verandahs, 9 W CFL may be installed instead of 40 W/ 20 W tubes / 2 9 W CFLs. The lighting fixture needs to be brought down to 3.0 m (from ground level) instead of at ceiling. VII. Intelligent controller may be installed on street light feeders wherever it is yet to be installed. The suggested measure of energy conservation is to go in for 36 W high lumen tube with electronic ballast with mirror optic fittings for around 1221 fittings at a cost of Rs.6.1 lakhs. Alternatively, 28 W TFLs with fittings can be used at a cost of Rs.10.4 lakhs. In both cases, the pay back period is 4 months [6]. BUILDING AUDIT The percentage share of building energy consumption has been growing steadily over the years. Energy conservation in this sector can be approached both from improving the 45
AKGEC INTERNATIONAL JOURNAL OF TECHNOLOGY, Vol. 4, No. 1 efficiency of installed equipment as well as from improving the system efficiency. I. The overall specific energy consumption is in the range 1-11 kwh/m2/month. If only the building energy consumption is considered it is in the range 0.4-4.0 kwh/ m2/month. These values are lower than reference values. The low specific energy consumption is on account of no usage of room heaters, good use of natural ventilation and day lighting.[1] II. The specific energy consumption per person is in the range of 8-140 Wh/m2/person/month for overall energy. This is high because of the very low movement of people in Central Research and Testing Laboratories, Bangalore as compared to reference buildings.[1] III. The building energy is almost insensitive to ambient IV. temperature and weather conditions. The CPRI buildings can qualify as green buildings (because of their inherent low energy consumption) with capacity utilization, fine tuning and technology up gradation of the lighting and air conditioning systems. Their inherent design is in a ribbon form allowing good natural lighting and ventilation. V. The energy conservation potential for buildings is as follows: Lighting : 1.2-2.0 % (3.75-6.25 MWh/month) Air conditioners: 0.2 % (600 kwh/month) [6]. V. ENERGY AUDIT OF ELECTRICAL NETWORK The scope of energy audit is to identify how and where losses occur, and suggest appropriate engineering solutions along with economic implication to conserve the various forms of energy consumed. The detailed scope of work includes: Establishment of energy consumption pattern (daily, monthly and annual) Establishment of load pattern (daily, monthly and annual) Identification of energy conserving measures and financial analysis of their viability. The experimental work consists of the following: Visual inspection of the network and components Inventory of network components Collection of past data on power, energy and power factor Collection of meter and billing details Power measurement using a three phase power analyzer at various points in the network to establish the load balance Logging of energy data at various points to establish the energy balance. The monthly energy balance is given in table (6). While network losses are significant 27%* the major energy consumption is for lab test equipment which accounts for 47 %** [6]. TABLE 6 : TYPICAL MONTHLY ENERGY BALANCE S.N. Particulars Monthly energy MWh/month % 1 Total network loss 80.4 26.8* 2 Lighting 26.8 8.9 3 PC, fan, AC 38.3 12.8 4 Pumps 12.3 4.1 5 Lab test equipment 142.2 47.4** 6 Total 300 100 The study of the electrical network indicates that lab equipment and network account for nearly 47 % and 27 % of the energy consumption. The base line data on monthly energy consumption has been established at 300 MWh/month. Optimal use of 11 KV system can result in cost reduction because of the differential pricing at 11 KV and 220 KV levels of supply.[6] VI. CONCLUSION Incandescent lamp may be replaced with Compact Fluorescent Lamps whenever possible. For all lighting installations using fluorescent tubular lamps, mirror optic luminaries be introduced in a phased manner. Change to Electronic ballasts in place of conventional ballasts for all fluorescent tubular lamps in a phased manner. Replacement of all HPMV lamps to HPSV lamps along with suitable ballasts and external igniters and also check suitability of light points at ceiling and its height. Wherever possible and not yet done, replace tubular fluorescent lamp street lights with sodium vapor lamp, for better intensity and overall economy. Timer controlled switches be installed where it is required but not yet installed like substations, outside lights etc. Segregation of lighting circuits and provision of separate switching devices where lighting functions are different. Provide door switches in un-attended rooms for control of lighting. Make provision to allow maximum sunlight in working place during day time, where it is possible. VII. REFERENCES [1] Siddhartha Bhatt.M., N. Rajkumar, S. Jothibasu, R. Sudirkumar, G. Pandian and K.R.C. Nair Commercial and Residential Energy Labeling Journal of Scientific and Industrial Research, Vol.63 (2004) APR 98 [2] IPS. Paul, SP Sabberwal, SC Kaushik, Interfacing Energy Management, Energy Audit Means to Implement & Role of Computer based EMS with Thermal Generation Udyog Pragati June 1995. 46
EFFICIENT USE OF ELECTRICAL POWER [3] IPS Paul, M.S. Lally Role of compact fluorescent lamps for energy conservation presented at national conference on lighting for 21st century organized by ISLE and CPRI, Bangalore 1997. [4] Energy efficiency in lighting an overview, Central Electricity Authority-CEA, 2004. [5] http://powersearch.cpri.res.in, www.gyanshakti.com [6] CPRI report No. CPRI/ECDD/EA/014/06. Dr. I P S Paul is currently a Professor at the Department of Mechanical Engineering, Amity University, Greater Noida. Earlier he was with AK Garg Engineering College, Ghaziabad. Obtained BE (Mech.) from NIT Bhopal, MBA from University of Delhi, Diploma in Energy Management, Italy and PhD from IIT Delhi. He has served as power research engineer and trainer in PSEB, NPTi, NTPC and CPRI. He has guided PhD, MTech and MBA thesis and has 108 research papers to his credit. 47