Turn the connected load and your brightness-step hours into daily, monthly and yearly energy and cost, and test an LED conversion.
A series circuit draws its power through the isolating transformers, the cable and the CCR, so the meter reads more than the lamps alone. Runway lights also spend most of their hours below full brightness. This tool follows the load from the fixtures back to the CCR input, weights it by the hours spent at each step, and prices the energy at your tariff.
Planning assumption. See Calculator #18 for a loss breakdown.
Planning assumption. The Cable Power Loss calculator gives the figure for your cable.
Load is shown as a percentage of the full-brightness input. The defaults use the current squared as a simple approximation for a plain lamp load on a 6.6 A circuit. Overwrite them with measured or manufacturer values, especially for LED fixtures, whose power does not fall that way. The step currents shown are for a 5-step CCR. For a 3-step CCR (4.8, 5.5 and 6.6 A) use the B3, B4 and B5 rows, set the other hours to 0, and enter about 53 %, 69 % and 100 % for a plain lamp load.
| Step | Current | Load (% of full) | Hours per day |
|---|---|---|---|
| B1 | 2.8 A | ||
| B2 | 3.4 A | ||
| B3 | 4.1 A | ||
| B4 | 5.2 A | ||
| B5 | 6.6 A |
A transformer lightly loaded by a low-wattage LED is usually less efficient than at its design load. Enter the data-sheet value at the LED load; leave blank to use the efficiency above.
The same CCR efficiency and step profile are used for the new fixtures, and the cable loss stays at the same kW because the circuit current does not change; the transformer efficiency is the one above unless you enter an LED value. CCR efficiency also falls at light load, so treat the saving as an upper estimate. LED loads can change CCR loading and power factor, so confirm compatibility with the CCR manufacturer.
| Step | Input (kW) | Hours / day | kWh / day | kWh / year | Cost / year (₹) | Share (%) |
|---|
Calculated planning figures from the entered step profile — not metered data.
Every step is shown so the result can be checked by hand.
The fixture load is carried back through the transformers, the cable and the CCR.
Each brightness step draws a fraction f of the full-brightness input. Energy is the sum over steps of input times hours.
Monthly figures are the yearly figure divided by 12. A demand charge, if any, is the full-brightness kVA times the monthly rate times 12.
The same chain and profile are run with the new fixture watts. The cable loss stays at the same kW, because the circuit current does not change. The saving is the energy cost plus any demand charge saved, and payback is the retrofit cost divided by that yearly saving.
| Item | Value |
|---|---|
| 100 × 45 W, 90 % transformers | 5.00 kW |
| 2 % cable loss, 92 % CCR | 5.54 kW input |
| Σ (f × hours), 10 h a day | 4.290 |
| Daily energy | 23.78 kWh |
| 365 days | 8,680 kWh |
| At ₹8 per kWh | ₹69,442 |
| LED at 15 W, same profile | 3,007 kWh |
| Saving | 5,673 kWh, ₹45,387 |
It applies one step profile to the whole circuit, so it suits a single circuit or a set run together. Efficiencies are held constant across steps, although real transformers and CCRs vary with loading. Step load fractions are your inputs, so use measured or manufacturer values for LED fixtures.
Quick answers on turning connected load and brightness-step hours into energy and cost.
It turns the connected load and your brightness-step hours into daily, monthly and yearly energy and cost, and tests an LED conversion. A series circuit draws its power through the isolating transformers, the cable and the CCR, so the meter reads more than the lamps alone. The tool follows the load from the fixtures back to the CCR input.
The fixture load is carried back through the transformers, the cable and the CCR. Input power is the number of fixtures times the watts per fixture, divided by the transformer efficiency, multiplied by one plus the cable loss percentage, and divided by the CCR efficiency. The efficiencies and cable loss are planning assumptions you can replace with data sheet values.
Each brightness step draws a fraction of the full-brightness input, and energy is the sum over the steps of input times hours. The defaults use the current squared as a simple approximation for a plain lamp load on a 6.6 A circuit. Overwrite them with measured or manufacturer values, especially for LED fixtures, whose power does not fall that way. For a 3-step CCR, use the B3, B4 and B5 rows, set the other hours to 0, and enter about 53, 69 and 100 percent for a plain lamp load.
Yearly energy is daily energy times the operating days, and cost is yearly energy times your tariff. Monthly figures are the yearly figure divided by 12. A demand charge, if any, is the full-brightness kVA times the monthly rate times 12, where kVA is the input power divided by the CCR input power factor. Set the demand charge to 0 if your tariff has none.
The same chain and step profile are run with the new fixture watts. The cable loss stays at the same kW because the circuit current does not change. The saving is the energy cost plus any demand charge saved, and payback is the retrofit cost per fixture times the number of fixtures, divided by the yearly saving. A transformer lightly loaded by a low-wattage LED is usually less efficient, and CCR efficiency also falls at light load, so treat the saving as an upper estimate. Confirm LED compatibility with the CCR manufacturer.
For 100 fixtures of 45 W with 90 percent transformers, 2 percent cable loss and a 92 percent CCR, the input is 5.54 kW. With 10 hours a day on the default profile, daily energy is 23.78 kWh and yearly energy is 8,680 kWh, which costs 69,442 rupees at 8 rupees per kWh. LED fixtures of 15 W on the same profile use 3,007 kWh, a saving of 5,673 kWh or 45,387 rupees a year.
It applies one step profile to the whole circuit, so it suits a single circuit or a set run together. Efficiencies are held constant across steps, although real transformers and CCRs vary with loading. The cost is energy only at the tariff you enter, so maintenance, lamp replacement and tariff changes are not included.
No. They are calculated planning figures from the step profile you enter, not metered data. Costs are estimates and shall be checked against metered data and the applicable tariff.
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