Technical Articles
The customer is a MNC, Food & Beverage Company and a part of the West Bengal Tariff system. The customer has 2 transformers, having a rating of 2MVA and 3 MVA respectively. The AHF was installed at the LV side of the 2 MVA transformer. This application note presents the effect of AHF installation on the electricity bill and saving thereof.
The West Bengal Electricity Board has kWh billing and penalty/ Incentive rates applicable as follows:
33 kV Industrial Consumer with F(bt)* type tariff system:
| F (bt) Type of Consumers | Energy Charge Rs/kWh | Demand Charges (Rs./ KVA/ month) | |||
| Normal TOD | 06.00 hrs. - 17.00 hrs. | All Units | Normal | 6.99 | 384 |
| 17.00 hrs. - 23.00 hrs. | All Units | Peak | 8.38 | ||
| 23.00 hrs. - 06.00 hrs. | All Units | Off-Peak | 5.24 | ||
* F(bt) is a tariff structure in the West Bengal state tariff scheme applicable to 33kV industrial consumer.
| Slab | Power Factor (PF) Range | Power Factor Rebate & surcharge On Energy Charge in Percentage For the Year 2015-16 | ||
| For Consumers Under TOD Tariff | ||||
| Normal Period (6-00 AM to 5.00 PM) | Peak Period (5.00 PM to 11.00 PM) | Off-Peak Period (11.00 PM to 6.00 AM) | ||
| 1 | PF >0.99 | 8 | 9 | 6 |
| 2 | PF >0.98 & PF ≥0.99 | 7 | 8 | 5 |
| 3 | PF >0.97 & PF ≥0.98 | 5 | 6 | 4 |
| 4 | PF >0.96 & PF ≥0.97 | 4 | 5 | 3 |
| 5 | PF >0.95 & PF ≥0.96 | 3 | 4 | 2 |
| 6 | PF >0.94 & PF ≥0.95 | 2.25 | 3 | 1.5 |
| 7 | PF >0.93 & PF ≥0.94 | 1.5 | 2 | 1 |
| 8 | PF >0.92 & PF ≥0.93 | 0.75 | 1 | 0.05 |
| 9 | PF >0.86 & PF ≥0.92 | 0 | 0 | 0 |
I. Bill Parameters
The following parameters were recorded before installation of AHF from customer's electricity Bill Details are as below
1. Supply Voltage - 33 kV
2. Contract Demand - 3150 kVA
3. Fixed demand charges - 384 Rs/kVA
4. Percentage Chargeable - 85 % of contract demand = 3150 x 0.85 = 2678 kVA
5. Power Factor - 0.9770 (average)
6. Load Factor (%) - 61.6973. % (% of contract demand)
1. Maximum Demand (MVA)
| Normal (MVA) | Peak (MVA) | Off-Peak (MVA) | Penalty Applicability |
|---|---|---|---|
| 2.512 | 2.464 | 2.576 | No Penalty On Maximum Demand |
2. Apparent Power Calculations (MVAh)
| MVAh | ||||
| Normal | Peak | Off - Peak | ||
| A | Present Meter Reading | 47757.2 | 26826.1 | 31944.5 |
| B | Previous Meter Reading | 47220.5 | 26534.1 | 31583.4 |
| C = A-B | Difference | 536.3 | 292 | 361.1 |
| D = MF*C | Where MF =1000 | 536300 | 292000 | 361100 |
3. Real Power Billing (MWh)
| MWh | ||||
| Normal | Peak | Off - Peak | ||
| E | Present Meter Reading | 45839.2 | 25805.4 | 30763.7 |
| F | Previous Meter Reading | 45315.6 | 25519.1 | 30411.5 |
| G = E-F | Difference | 523.6 | 286.3 | 352.2 |
| H = MF x G | Where MF =1000 | 523600 | 286300 | 352200 |
4. Electricity Charges
| Billing Details | ||||||
| Normal | Peak | Off - Peak | ||||
| I | EC (Rs/kWh) | 6.99 | 8.38 | 5.24 | ||
| Recorded PF | 0.9763 | 0.9805 | 0.9754 | |||
| J | PF REB(-) | 5% (Slab3) | 8% (Slab2) | 4% (Slab3) | # | |
| L= H*I | 3659964 | 2399194 | 1845528 | 7904686 | AMOUNT (Rs) PAID IF NO REBATE ON PF | |
| Disc =%J x L. | Discounts | 182998.2 | 19135.5 | 73821.12 | 448754.8 | ACTUAL REBATE ON PF |
II. Bill Calculations
1. Part A - fixed charges
| Contract demand | 3150 kVA |
| Actual Consumption | < 2576 kVA |
| Chargeable | 85 % of Contact demand + Additional KVA consumed |
| Additional KVA consumed | 0, hence 85 % of contract is payable |
| Actual consumption | 3150 x 0.85 |
| 2678 kVA |
Consumed kVA is lesser than 85 % of contact demand, hence irrespective of any saving in kVA, customer has to pay a minimum sum
= Rs. 0.85 x 3150 x 384
= Rs. 10,28,352
2. Part B - kWh charge
The total kWh consumed were as follows:
| kWh | Rs/kWh | |
| Normal | 523600 * 6.99 | 3659964 |
| Peak | 286300 * 8.38 | 2399194 |
| Off-Peak | 352200 * 5.24 | 1845528 |
| Energy charge to be paid for energy consumed | 7904686 |
3. Part C - Incentive & Penalty
According to Part I, Point 7 of the note, the incentive applicable to the customer would be 5%, 8% & 4% in normal, peak and off-peak hour's resp.
| Normal | 5% (slab3) * 3659964 | 182998 |
| Peak | 8% (Slab2) * 2399194 | 191936 |
| Off-Peak | 4% (Slab3) * 1845528 | 73821 |
| Energy charge to be paid for energy consumed | 448755 |
Fig 2 I-THD waveform variation before and after AHF installation
Fig 3 -Value of VTHD AND ITHD before and after AHF installation
| Parameters | AHF OFF | AHF ON (Only harmonic correction) | AHF ON (Both PF & harmonic correction) |
|---|---|---|---|
| % VTHD | 3.1 | 1.9 | 1.9 |
| % I-THD | 13.8 | 6.6 | 7.0 |
| Pf | 0.987 | 0.992 | 0.996 |
Fig 4-Value of RMS Current before and after AHF installation
| RMS Current | R | Y | B |
|---|---|---|---|
| AHF ON | 1478 | 1377 | 1369 |
| AHF OFF | 1501 | 1408 | 1406 |
IV. Scope for saving
1. Direct Saving through increase in incentive
According to the West Bengal Electricity board if a PF above 0.991 is maintained, the PF is rounded to unity and maximum incentive can be obtained from the same. Installed E&A AHF filter improved the customer PF from 0.977 to 0.996, leading to maximum incentive obtained from the electricity board.
According to Part I, Point 7 of the application note, the maximum incentive that can be obtained is 8%, 9%, 6% during normal, peak and off-peak hours respectively
Considering the customer gets maximum percentage incentive, the rupee incentive would be as follows.
| Normal | 8%(Slab1) * 3659964 | 292797 |
| Peak | 9%(SIab1) * 2399194 | 215927 |
| Off-Peak | 6%(Slab1) * 1845528 | 110732 |
| Incentive in rupees after unity power factor | 619456 |
IV. Scope for saving
1. Direct Saving through increase in incentive
According to the West Bengal Electricity board if a PF above 0.991 is maintained, the PF is rounded to unity and maximum incentive can be obtained from the same. Installed E&A AHF filter improved the customer PF from 0.977 to 0.996, leading to maximum incentive obtained from the electricity board.
According to Part I, Point 7 of the application note, the maximum incentive that can be obtained is 8%, 9%, 6% during normal, peak and off-peak hours respectively
Considering the customer gets maximum percentage incentive, the rupee incentive would be as follows.
2. Saving through reduction in line current
The harmonic analysis was done before and after AHF installation and the following results were obtained from the same
It can be seen that the reduction in current is about 30 A (avg). Reduction in line current would lead to reduction of transformer losses and copper losses. This reduction would be responsible for reduction in power consumed hence leading to direct saving for the customer. The installed AHF also consumes active power.
The AHF was turned on during the peak hours of operation and hence the calculations for the same have been done as follows.
| Power with AHF | 1007.99 | kW | For 180 hrs./month | 181438.93 | kWh |
| Power Without AHF | 1009.83 | kW | For 180 hrs./ month | 181769.88 | kWh |
| Difference | -1.83 | kW | For 180 hrs./ month | -330.95 | kWh |
Hence a monthly reduction of 330 kWh can be obtained during the peak period. Taking a percentage of the saving obtained, assuming that the same percentage saving in the other normal and off peak-periods, we can obtain the approximate saving in the other operating hours, as follows:
1. Peak hours
330 kWh x 8.38 = Rs 2773
Percentage saving = 2773 / 2399194 = 0.116%
Approximating and applying the same percentage saving to the other times of day.
2. Off peak Hours
Saving: 0.116%x 1845528 = Rs 2133.38
3. Normal Hours
Saving: 0.116%x 2659964 = Rs 4230
Total Saving due to reduction in kWh = Rs 9138 per month
Conclusion
The following illustration represented the case of a MNC, Food & Beverage Company and a part of the West Bengal Tariff system. The billing details of the consumer were first calculated for a previous month. The same bill was then considered for better power factor and hence applicable incentives post AHF installation were projected. The overall power saving with and without Active Harmonic Filter is as follows
| Total Bill | Without AHF | With AHF | Saving |
|---|---|---|---|
| Demand Charge | 1028352 | 1028352 | 0 |
| Total EC | 7904686 | 7904686 | 0 |
| LF Rebate | -92968 | -92968 | 0 |
| PF Rebate | -448755 | -619456 | 170701 |
| MCVA Charges | 267283 | 267283 | 0 |
| Other Arrers Charges | 480857 | 480857 | 0 |
| Total ED (15%) | 1357656 | 1357656 | 0 |
| Reduction In kWh | 0 | -9138 | 9138 |
| Meter Rent | 2400 | 2400 | 0 |
| Total | 10499511 | 10319672 | 179839 |
It can be seen that the monthly saving of the customer is Rs 1,79,839 INR and taking into consideration the total MVA of the customer, an AHF of Rs 18,00,000 is required for meeting the 5 MVA capacity.
| Cost of AHF | 1800000 |
| Monthly Reduction in Electricity Bill | 179839 |
| Payback Period (in Months) | 10.01 |
Sourav Dasmodak,
Product Management & Marketing (Powergear - ACB)Product Owner of Air Circuit Breaker (ACB) of Lauritz Knudsen for Domestic & International Market. I can talk to you about Electrical Products' Sales, Business Development, Market Expansion, Cracking Critical Strategic Account, handling Key Account & of course how to develop & motivate Channels along with the organizational growth. Having near about one and a half decade of experience across the country with major electrical manufacturers (Top 4).
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