चलाउने खर्च तुलनाCompare operating cost

दक्ष मोटरले वर्षमा कति बिजुली बचाउँछ? How much can a more efficient motor save each year?

एउटै shaft load मा पुरानो र नयाँ मोटरलाई तुलना गर्नुहोस्। Input kW, वर्षको युनिट, चलाउने खर्च र साधारण payback हेर्नुहोस्। Compare an existing and candidate motor at the same shaft load. See input kW, annual kWh, operating cost, and simple payback.

मोटर र चल्ने समयMotor and operating schedule

Nameplate rated outputNameplate rated output

यो shaft मा दिने mechanical output हो, input power होइन।This is mechanical shaft output, not electrical input power.

चलिरहेको loadOperating load

Rated output को कति प्रतिशत shaft load चलिरहेको छ?What share of rated shaft output is actually being used?

दिनमा चल्ने समयOperating hours per day

h/day

वर्षमा चल्ने दिनOperating days per year

days

दक्षता र मूल्यEfficiency and price

Aअहिलेको दक्षताExisting efficiency

सम्भव भए यही load मा datasheet वा test value राख्नुहोस्।Use a datasheet or tested value at this load when possible.

Bनयाँ मोटरको दक्षताCandidate efficiency

नयाँ मोटरको पनि उही load point को दक्षता राख्नुहोस्।Use the candidate motor's efficiency at the same load point.

बिजुलीको energy दरElectricity energy rate

Rs/kWh

आफ्नो bill को हालको लागू दर राख्नुहोस्।Enter the current applicable rate from your bill.

नयाँ मोटरको थप लागतIncremental upgrade cost

किन्ने र जडान गर्ने थप लागत। Payback नचाहिए 0 राख्नुहोस्।Extra purchase and installation cost. Enter 0 to skip payback.

वर्षको तुलनाAnnual comparison

वर्षको चलाउने खर्च बचतAnnual operating cost saving Rs 14,927 प्रति वर्ष, energy charge मात्रper year, energy charge only

Aअहिलेको मोटरExisting motor

Input power: 9.54 kW
वर्षको ऊर्जाAnnual energy: 28,611 kWh
वर्षको खर्चAnnual cost: Rs 3,43,330

Bनयाँ मोटरCandidate motor

Input power: 9.12 kW
वर्षको ऊर्जाAnnual energy: 27,367 kWh
वर्षको खर्चAnnual cost: Rs 3,28,402

बच्ने input powerInput power saved0.415 kW

वर्षको ऊर्जा बचतAnnual energy saving1,244 kWh

ऊर्जा घट्ने भागEnergy reduction4.3%

वर्षको चल्ने समयAnnual operating time3,000 h

साधारण paybackSimple payback6.0 years

यो replacement recommendation होइनThis is not a replacement recommendation

Load र efficiency स्थिर मानिएको छ। नयाँ मोटरले उही shaft load धान्छ भन्ने मान्यता छ। Varying load, demand charge, power-factor penalty, rewinding, downtime, motor speed, VFD, maintenance र उत्पादनमा पर्ने असर यसमा छैन। Motor specialist ले application र मापन जाँच्नुपर्छ।The model assumes constant load and efficiency, and that the candidate can carry the same shaft load. It excludes varying load, demand charges, power-factor penalties, rewinding, downtime, speed changes, VFD effects, maintenance, and production impact. A motor specialist must check the application and measurements.

हिसाब कसरी हुन्छ?How the calculation works

दुवै मोटरले एउटै shaft output दिन्छन् मानिन्छ। दक्ष मोटरलाई त्यही कामका लागि कम electrical input चाहिन्छ।Both motors are assumed to deliver the same shaft output. The more efficient motor needs less electrical input for that work.

rated output kW = hp × 0.746, or entered kW
shaft load kW = rated output kW × load %
motor input kW = shaft load kW ÷ efficiency
annual hours = hours/day × operating days/year
annual energy kWh = input kW × annual hours
annual saving = (old input kW − new input kW) × annual hours
annual cost saving = saved kWh × entered Rs/kWh
simple payback = incremental upgrade cost ÷ annual cost saving

दक्षता 88% भए 0.88 प्रयोग हुन्छ। Motor efficiency, power factor र load एउटै कुरा होइनन्।An efficiency of 88% is used as 0.88. Motor efficiency, power factor, and load are different quantities.

नमुना हिसाबWorked example

15 hp motor 75% load मा दिनको 10 घण्टा र वर्षमा 300 दिन चल्छ मानौं। अहिलेको दक्षता 88%, नयाँको 92%, energy दर Rs 12/kWh र थप लागत Rs 90,000 छ। यी सबै नमुना input हुन्।Assume a 15 hp motor runs at 75% load for 10 hours a day and 300 days a year. Existing efficiency is 88%, candidate efficiency is 92%, energy costs Rs 12/kWh, and the incremental upgrade costs Rs 90,000. Every value is illustrative.

15 × 0.746 × 75% = 8.3925 kWshaft मा चाहिने outputrequired shaft output

8.3925 ÷ 88% = 9.5369 kWअहिलेको inputexisting input

8.3925 ÷ 92% = 9.1223 kWनयाँ motor inputcandidate input

0.41465 × 3,000 = 1,243.95 kWhवर्षको ऊर्जा बचतannual energy saving

1,243.95 × Rs 12 = Rs 14,927वर्षको energy charge बचतannual energy-charge saving

Rs 90,000 ÷ Rs 14,927 = 6.0 yearsसाधारण paybacksimple payback

स्रोत र मान्यताSources and assumptions

US Department of Energy, Premium Efficiency Motor Selection and Application Guide, checked 8 Sep 2026. DOE Equation 3-5 compares input kW at the same load using motor hp and operating-load efficiencies. Equation 3-6 multiplies saved kW by annual operating hours. The guide says this direct method is for specified constant loads.
US Department of Energy, Determining Electric Motor Load and Efficiency, checked 8 Sep 2026. It defines efficiency as useful output divided by input, describes load as actual output relative to rated output, and recommends efficiency values at the operating load point.
NIST Guide to the SI, Appendix B.9, checked 8 Sep 2026. NIST lists horsepower at 745.6999 W and electric horsepower at 746 W. This calculator uses the DOE motor guide's rounded 1 hp = 0.746 kW.
Nepal Electricity Authority, Consumer Tariff Rates, checked 8 Sep 2026. Enter the energy rate that applies to your own consumer category and bill. This page does not assume one Nepal-wide motor tariff.

75% load, 88% र 92% दक्षता, 3,000 hours/year, Rs 12/kWh र Rs 90,000 नमुना मात्र हुन्। Constant-load हिसाब हो। फरक load period भए हरेक period छुट्टै हिसाब गरेर savings जोड्नुहोस्।The 75% load, 88% and 92% efficiencies, 3,000 hours/year, Rs 12/kWh, and Rs 90,000 are examples only. For distinct load periods, calculate each period separately and add the savings.