Energy Conservation

  • Energy Saving Devices like occupancy sensor/Timers for Window AC/ Split Units have been installed

    In The Department of Telecom the Telephone Exchange buildings are highly energy intensive buildings operating round the clock. The energy conservation measures were initiated in the year 1998 much prior to the enactment of the Energy Conservation Act 2001.

    Telephone Exchange buildings consume energy in Lighting, Air-conditioning and Power plant(AC-DC Rectifier) 48 V DC for Exchange Equipment. Department of Telecom introduced the concept of Bench Mark prescribing energy conservation norms, developed new technology AC Package unit and SMPS Power Plants to conserve energy. Further no cost, low cost measures have been carried out in the Department which has resulted into huge energy savings. The measures taken in DOT are:

    • Monitoring of energy consumption :-

      The electricity bills received from State Electricity Board are scrutinized thoroughly and checked specifically for Power Factor, electric units consumed and violation of Maximum Contract Demand etc. The following parameters are being monitored regularly:

      • Electric Unit Consumed (Unit / Line / Month) - A
      • Electricity Charges (Rs / Line / Month) - B
      • Penalties in Energy bills (Rupees) - C

      For deficiency if any corrective measures are being taken. Capacitor Panels have been installed in almost all exchanges and power factor of 0.99 is being maintained. Today the situation is that the Department gets incentives for maintaining better power factor rather than paying penalties.

    • Benchmark

      Department of Telecom introduced the concept of Bench Mark prescribing energy conservation norms for Telephone Exchange buildings in the year 2000.

      The benchmark parameter prescribed was Unit/ line / month

      Unit = Electric units (kwh) consumed during a month

      Lines = Total no. of Telephone exchange lines

    • Lighting

      The lighting scheme inside the switch room has been designed for General lighting 100 lux and Task Lighting 150 lux. If the equipment manufacturer provides luminaries along with the switch equipment no separate Task Lighting is provided. The measures taken in DOT are:

      • 1 x 36 w mirror optic fluorescent tube fittings are only used in Telecom buildings.
      • CFL fittings are being used in common areas viz. corridor, toilets, lift lobby, Staircase and parking etc.
      • The control for the General Lighting provided near entrance of the switch room and for the Task Lighting near the switch racks.
      • Surrounding dcor- Light colour paints in exchange rack panels, walls, ceilings etc. for better reflection.
      • Lighting system based on solar power introduced in rural exchanges.
    • Air-conditioning

      The A.C. package units of 7.5 TR / 10 TR capacities available in the market are designed at 0.7 Sensible heat factor (70% dry heat + 30% latent heat). This unit when used for electronic exchange equipment cooling having high sensible heat load, 30% energy is wasted. These units are not suitable for continuous 24 hours operation for electronic exchanges and were being replaced after 4 to 5 years of operation due to performance deterioration and poor quality

      The Telephone Exchanges are having high Sensible Heat load. Department of Telecom developed the new technology Sensible Heat AC Package Units for use in telephone exchanges. The salient features of Sensible Heat AC Package Units are:-

      • Rated capacity : 10 + 1 TR & 7 + 0.5 TR (Sensible cooling capacity).
      • Ambient air temperature: 43 0 C
      • Supply air temperature: > 16 0 C
      • Air inlet temperature: 25 0 C ( DB)
      • Saturated suction temperature: Between 9 0 C & 10 0 C
      • Saturated discharge temperature : Maximum 53 0 C
      • Air quantity: 650 750 CFM/TR
      • Sensible heat factor: 0.95


      Achieved by reducing 1/3 of the effective coil areas of cooling coil through solenoid valve arrangement. (No heaters, humidifyers used)

      Hot gas reheats:

      50% of waste heat rejected to condenser in one of the circuit of the AC unit is utilized.

      Condenser fan:

      Variable speed/ two speed fan motor. (Speed to vary depending on-ambient temperature/Compressor head pressure)


      Energy efficient motor as per IS 12165

      The high Sensible heat units designed by DOT at 0.95 Sensible heat factors are energy efficient units consuming 30% less energy. Heaters and humidifiers have been eliminated. Due to better reliability of the units, This has resulted in to:-

      • 30 % Energy saving.
      • Reduction in initial cost.
      • The prescribed span of life of package units raised from 6 years to 9 years in DOT.
      • Trouble free operation for the past 10 yrs.
      • The standby units reduced from (N+N) to (N+1)
    • AC-DC Rectifier (Power plant)

    • The modernization and expansion of telecom network in DOT called for compact, flexible, reliable, easily transportable power plant having compatible operating characteristics with respect of telecom equipments. Hence the concept of Switch Mode Power Supply (SMPS) technology has been introduced in DOT. The salient features of SMPS technology are :-
      • SMPS based Power Plant use very high frequency switching
      • Size of the transformers and chocks is reduced to 10-15% of the conventional SER/Thyristors Controlled Power Plants.
      • Being small in size and light in weight
      • Being light weight these power plants are being installed close to technical room, even in the equipment room itself, which reduces the voltage drop to make the system more efficient.
      • Very high conversion efficiency of 85%
      • Power factor of 0.9 absolute

      As compared to the earlier conventional units the power characteristics are greatly improved in SMPS units such as transient Response, Harmonic Distortion, power factor(0.9 absolute), efficiency (85 %), energy efficient, economical and safe for telecom equipment.

    • No Cost Measures:-

      • Contract maximum demand rationalization :

        The contract maximum demand to the level of actual maximum demand as per the past consumption and immediate future plans Rationalized.

      • Improvement of Power factor:

        Power factor in the range of 0.97 to 0.99 (lagging) is being maintained. Dept is getting rebate.

      • Switch off stand-by transformer: To save no load losses ideal(stand by) transformer on HT side is switched off -one at a time on fortnightly rotation.
      • Cooling range adjustment for AC space by thermostat:

        By adjustment of thermostat setting for desired temperature

      • Revision of operating parameter:

        The optimum operating conditions for Air conditioning inside the switch room revised from 20 + 2 0 C with 40% Humidity To 23 + 2 0 C with 40-60% Humidity

      • Cooling load minimization of unutilized conditioned space:

        In the switch room the exchange equipment portion have been partitioned to minimize the cooling load.

      • The supply air grills/ diffusers/return air grills of unutilized space are closed.

      • Scaling down excess level of illumination:

        • Excess lamps and fixtures have been removed.
        • Faulty ballast and lamps have been replaced.
        • Luminaries/lamps are being cleaned periodically
          • dust decreases lighting levels by 20% to 30%.
      • Periodic cleaning of filters of Air Conditioners

        The filters of the window Air Conditioners and Package Units are being cleaned periodically every fortnight.

      • Water heater setting at optimum temperature level

        The thermostat of the water heater/ Geysers set at the desired /optimum temperature.

      • Switching off lights in unmanned areas:

        Lights in unmanned areas switch off manually.

      • Load balancing:

        Equalization of load in all three phases is being done. & Maintenance schedule is strictly adhered to.

    • Low Cost Measures

      • Energy Saving Devices like occupancy sensor/ Timers for Window AC/ Split Units have been installed
      • Timers/Photo cell switches for yard lighting provided (switching off 50 % light at midnight)
      • Low watt ballast/ Electronic ballast for fluorescent fittings are being used in replacement of faulty copper ballast .
      • Energy saver T-5 fittings (28 watt)& Electronic ballast fittings with halo-phosphate 36 watt lamp are being used.
      • All exhaust fans in multistoried buildings operated through Timer control.
      • 9/11 watt CFL fittings are being installed in corridors, bathrooms and other common areas
      • Automatic water level controller provided in over-head tanks to regulate operation of pump sets.

      The equipments, which have out lived their prescribed life, consume more energy and low on energy efficiency, are being replaced in a phased manner. Dry type Transformers have been installed in replacement of out lived oil filled type transformer as the losses are about 15% lower. The existing out lived lifts are being replaced by V.V.V.F Technology Lifts

    • General:-

      • A core group consisting of technical and financial members has been setup in the department to monitor the progress on implementation of Energy Conservation measures.
      • The item of Energy Conservation introduced in the MIS for regular monitoring in BSNL Telecom circles.
      • Orientation Courses on energy audit and energy conservation are being conducted in training centers to bring awareness among the staff and for closer understanding of the need for energy saving.
      • Orientation Courses on energy audit and energy conservation are being conducted in training centers to bring awareness among the staff and for closer understanding of the need for energy saving.
      • Separate head of accounts under operating expenses for electricity charges have been opened for ease of accounting/assessment of the energy savings achieved.
    • Other New Technology

      • Panel Coolers (new development)

        Panel cooler concept is nothing new and it is similar to the concept of domestic refrigerator. The space enclosed by the panel cooler is utilized for housing small equipment racks or BTS/OFC (UHF)/ IMPCS systems. The basic purpose is to segregate the equipments for the purpose of air-conditioning instead of air-conditioning the entire room space.

      • The cooling capacity required is drastically reduced. It is a proven technology that the built-in refrigerant circuit of a domestic refrigerator is more reliable as compared to conventional window/ split type units. Thus maintenance problem will be less and there is energy savings.

      • Geo Thermic

        The relative constant temperature in the depth of approximately 3-4 meter under the earth surface provides the simple and cost effective solution for cooling and heating. The thermal energy (Geo Thermal heat) i.e. stored underneath the earth is available all the time and the flow is not affected by seasonal variation and outside temperature.

      • In the new bio-technology faculty building of IIT, Kanpur funded by the then Communication Minister Sh. Arun Shorie, the cooling provision has been made by geo thermic principle and has been working satisfactorily.

        Results achieved

        • In 2000 (Unit/ line / month) = 4 -10 (Found varying for different state units)
        • In 2007 (Unit/ line / month) = 2.5 - 5.0

    This shows a substantial reduction in energy consumption with expansion of Telecom network.

    We must conserve our resources, make energy conservation a mission and thereby reduce the operating cost for sustainable development and maximizing profit.

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