Energy Monitoring Need in Buildings

The article shows how the safety of the utility equipment as a system is ensured against the breakdown related deviations by prompt monitoring of their energy consumption. - Ashok Sethuraman

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Energy Monitoring Need in Buildings

The building needs electricity and energy monitoring now to ensure equipment in a building are working safely, rationally and optimised for the sustained energy and health of buildings. The lights, fans, pumps and the AC equipment, DG set, water heaters etc need to be metered first in terms of KWH and run hours so that the cumulative run hours and the accumulated KWH of the utility will show the healthiness of the equipment that are running for many years. This article shows how the safety of the utility equipment as a system is ensured against the breakdown related deviations by prompt monitoring of their energy consumption.

Electrical Incoming Parameters

The case study building is a residential gated community multi-storeyed apartment of say 100 flats which has a transformer of 250 KVA capacity. (These case studies can be applied to any commercial building as well). Here, are the steps to be taken during installation and maintenance. The steps towards energy monitoring need based on safety aspects are:

  • In the EB incoming MV panel, install a high voltage or low voltage relay which will give audio visual alarm whenever the 415 volts side Voltage is going High or Low below 400 and above 415 volts setting done in the relay.
  • The transformer is having OLTC, mostly Off Load Tap Change over function in the old buildings (in the latest building only, On-Load-Tap-Changer Transformer has come). We have to monitor the 415 Volt side and set the tapping correctly such that it is around 400 to 410 volts band that is equal to 230 to 235 volts single phase. The lights sustain longer at 200 volts.
  • Many gadgets in the building will consume more power and break down prematurely when the individual flats are receiving more than 250 volts, so Transformer Off-Load Tap Changer to be set optimally and that the electrical breakdowns can be minimised and power consumption of the individual flat is getting reduced as well.
  • If the building transformer does not have the Tap-Change-Over provision, the individual flats to install the suitably rated KVA Automatic Voltage Stabiliser except for AC, and water heater circuits inside the flat. The AC, fridge and TV stabilisers definitely must have On-Delay timer, so as to avoid heavy voltage surges to these gadgets. In many instances, we find these gadgets fail simultaneously when there is power interruption from EB grid. This can be avoided.
  • Building to have only maintenance free earthing electrodes so that earth protection is steadily ensured for decades.
  • Install surge protection device (to guard against the switching surges from outside the building) at the Secondary of the Transformer or at the Incoming of the LT service and especially at the Lighting Switch Boards.
  • Very often due to electricity leakage in lighting in un-occupied areas, fire mishaps happen. This is one of the silently ignored factors that need to be taken care of. Also, never over-squeeze cables inside the concealed electrical conduits.

Open well Sub pump Single Phase 1.5 HP consumes 12 Amps, Single Phase 2 HP pump consumes 28 Amps.

  • The bore well sub pump, open well sub pump in the Sump etc are to be electronically monitored against overloading, under-loading of current (happening due to pump Dry Run), single phasing protection upto the pump end, apart from the current unbalance between the phases. This is fool-proof and reliable compared to thermal relay protections. The pump control panels to be fitted with KWH meter and run hour meter for each pump. This will show the relative water consumption, referring its power consumption and pump’s name plate.
  • Any pump motor, if fitted with the above two meters, will show the pump healthy running parameters like the loading with reference to its name plate, this can be generalised not only for the buildings but also for the industry. Further, the flow of water delivered per hour approximately is calculatable now, with reference to the pump’s name plate LPM, water in liters per minute and running KW.
  • Take the case study of 2 HP and 1.5 HP single phase Open well sub pumps used for each block of flats to pump water from sump to overhead tank. The sub pump rated 1.5 HP of block I consumed 12 Amps, and this is normal, whereas the Block II sub pump rated 2 HP Single Phase consumed 28 Amps, and its overload relay was bypassed too. This is abnormal. The capacitors inside the pump panel were failing frequently and the electrician used to replace routinely after few days of operation and kept it running, since no failures from pump end noticed.
  • The pressure gauge at each pump delivery was showing around 3 Kgsc pressure. So, it was assumed the pumps were running normal, but 2 HP pump’s power consumption was more than twice the normal pump’s power consumption, and increase in month’s EB bills.
  • On diagnosing the pump circuit, the flat 3 core cable was run in a GI pipe conduit for 15-meter distance from EB room to sump pump, and the whole length of GI pipe conduit was full of water inside, that got entered in the pipe due to seasonal rains from inspection pit. On visually inspecting the cable by pulling out, near to the sump pump location, the cable was found damaged and the inside bare copper strands of the cable were touching the water and GI pipe inner wall. Having identified the earth leakage, the Electrician immediately cut that damaged portion of cable and re-jointed the cable back.
  • Now, after rectifying that fault, the 2 HP pump was run and found the current dropped to 12 amps from 28 amps. So, the pump had consumed twice the power consumption per hour, and this pump runs daily around eight hours. So, the Earth Leakage in that damaged cable when goes un-noticed is an unsafe condition, hazardous, waste power consuming and needs to be attended on war footing.
  • If this earth leakage can happen here to one domestic pump and does not come to notice, then visualise thousands of motors driven machines or pumps etc in the industries, need to be ampere monitored routinely from safety angle. When safety fails, conservation fails and pollution (breakdown hazard) starts.
  • While talking about the input electric power consumption in terms of KW, the same has to be multiplied by the actual running hours daily or weekly or monthly or yearly as KWH – the energy consumed by the machine over the period of time. So, this run hour meter is mandatory to measure the cumulative energy now and also to know the machine output for the given averaged power input in units per hour for the given period of time.

For DG, UPL, units per liter of diesel is the key parameter. KW, KWH, Run hour meters are mandatory now for buildings.

  • Consumers are used to low cost subsidised electricity from the EB national and state grid till now. And today due to power cuts, they are forced to run DG set to meet statutory demands, but at high cost of electricity. After generating the electricity KWH from their own DG set, one is aware of the high cost of precious KWH.
  • It is wise to rightly undersize the DG KVA rating (and not to oversize) during procurement and in operation, the DG to load at an optimum of 50 per cent loading above and operate the DG set so as to get at 400 – 405 volts instead of 420-430 volts. This gives instant savings in diesel. The DG’s UPL in buildings to maintain around 2.5 in practice.
  • Though consumer wants DG set as an emergency standby in case of power cuts, it is practically seen, in many places the DG is operated at 10 to 20 per cent loading, and the user can get only 1 KWH unit per liter of diesel ie 1 KWH cost is equal to Rs 60, a huge waste. DG when runs at 35 per cent efficiency, and at NO load at output, the DG consumes tare load diesel, say a 62.5 KVA DG set consumes 6 liters of diesel per hour at zero output, this is idling consumption.
  • It should be ensured that the single-phase loads are distributed evenly across the three phases so that the unbalance between 3 phases is not more than 10 per cent of total DG set capacity. More the unbalance, this will lead to less UPL.
  • Since the running cost of DG is so high, plan the use of DG rationally when required only and load the same optimally. Make the DG as standby for emergency indispensable services, like the Lift and use the ACCL Automatic Current Circuit Limiter to limit the Wattage during DG run in each flat, and in common utilities.

AC’s Freon charging and running pressures matter most now. This can be monitored using IN-Situ Pressure Gauge inside. An undercharged AC runs for more hours for the given room’s cooling requirements. An overcharged AC consumes more power for the same room’s given cooling requirements.

  • This KWH meter is fitted to the AC power circuit to measure ACs cumulative KWH over a period. And the Run hour meter is wired from the AC compressor cut-in cut-out circuit to know the AC compressor Run hours. Both meters will show AC’s running health and efforts towards energy savings done or not.
  • Now Split AC erectors install the AC stabilizer near to the Outdoor unit, so as to reduce the line drop voltages from the Stabilizer to the AC compressor. But it is always better to assess AC health by knowing both the parameters like AC compressor Run Hours, AC machine Run Hours, and AC KWH in its Run hours to condition monitor AC efficiency.
  • During AC installation, add a KWH meter (priced from Rs 500 onwards) along with the run-hour meter costing Rs 300/- now consumer can analyse whether he or she is running equipment uselessly as a liability or he or she is fully utilising the equipment to its optimum efficiency?
  • So, for steady-Watt loads like tube light, fridge, storage water heater, room heater etc, consumer can think of simple retrofit of hour meter and for the varying KW loads and can plan to add 3 phase 4 wire KWH meter with CT or direct connect type.

Lighting System Parameters

  • Here, the lighting circuit also needs to be checked for its loop parameters and against earth leakage. One Lighting OEM supplied lakhs of LED tube lights to the group of textile mills few years back, on condition that, to extend the warranty clause, OEM insisted that each LSB must have maintenance free earthing protection and SPD device to protect tube lights against the switching surges from the heavy motor loads surrounding to the soft lighting loads.
  • As and when the light or row of lights is installed and switched on, consumer has to check and confirm with the plug-in Power Guard PG meter, the power consumption in watts, VA, PF, KVAR are okay at that instant, as they are constant watt loads only.
  • On the LED tube light installation, the light is steady only when earthing is correct. In one case study, the electrician by mistake hammered a nail on the concealed electrical conduit by mistake. And the LED tube light started flickering after that for some time and failed instantly. After any LED tube light replacement in place of existing old tube lights, we have to confirm the basic power parameters are all okay, to complete the LED tube lights replacement program.

Sewage Treatment Plant Workings

The blowers in STP plants are more in number in these multi-blocked apartments, and run for more hours of the day to maintain the oxygen demanded by the STP plant. Practically, this area is neglected by the building users. And they don’t replace the paper filter in time, at suction of blower for years. Instead, they need to retrofit on top now, a cubicle mesh box doubles the volume of the actual paper filter. Daily take out the pre-filter Fine Netlon mesh box and swipe clean with brush to ensure steady air intake volume.

Provide an ordinary U tube Manometer to show the air intake suction filter choke condition. The blower runs for more hours in achieve the BOD/COD function, if its air intake filter is choked. Also, if the twin-lobe blower’s internals are poorly maintained, this leads to higher blower-discharge temperature, and this leads to poor running efficiency of blowers. Here, we can install a temperature gauge with alarm function to alert against falling efficiency.

Conclusion

In Energy Management, buying energy efficient equipment is only half done. How efficiently user load and run the equipment is the vital half of energy day-to-day management by the users in buildings and industries now.

Energy measurement is the first step towards the energy management, whether daily or weekly or monthly logging of consumption depends on the usage and how the individual responds proactively. User must know what is the utility machine’s daily consumption as compared to the total consumption per day either in domestic or commercial segment.

Also, if more than one machine is there in premises, relative condition monitoring of daily KWH of two or more machine will prompt or provoke the consumer why the daily KWH difference between two or more machine in premises? The difference in KWH daily readings will prompt and motivate the energy conscious consumer to conserve energy, promptly.

So, Bureau of Energy Efficiency (BEE) can also give thrust and enforce the utility OEM to incorporate the energy monitoring of the 5-star rated equipment performance at the consumer end like retrofitting the KWH & Run hour meter on the same. Monitoring of the gadgets or appliances will prompt the user to adapt to energy conservation mode naturally and this makes both the ends meet in the National Mission of Enhanced Energy Efficiency in the Energy Monitoring and Control Aspects.