Upgrading Pellet Mill Motor – AC to DC Conversion

1. Introduction

Current Setup: 200 HP, 3-Phase, 440V AC Motor, 1440 RPM
Proposed Upgrade: 192 HP, 3-Phase, 400V DC Motor, 1440 RPM
Purpose: Increase efficiency, reduce energy consumption, and optimize performance in pellet mill operations.

2. Why Convert to a DC Motor?

Higher Efficiency: DC motors operate at 95% efficiency, compared to 92% for AC motors.
Precise Speed & Torque Control: Better load handling and smoother operations.
Lower Energy Consumption: Reduced power losses lead to significant savings.
Reduced Heat Generation: DC motors produce less heat, reducing cooling requirements.
Less Maintenance: Fewer moving parts compared to AC induction motors.

3. Power Consumption & Cost Savings

AC Motor Power Input:
- Power Factor: 0.85
- Efficiency: 92%
- Input Power: 162.17 kW
DC Motor Power Input:
- Efficiency: 95%
- Input Power: 150.77 kW
Power Savings:
- 11.4 kW saved per hour
- Annual Savings (if operated 24 hours/day, 300 days/year):
  - 82,080 kWh/year saved
  - Electricity Cost = ₹8/kWh
  - Annual Cost Savings = ₹6.56 lakh

4. Conversion Costs

Item	Cost (Approx.)
192 HP DC Motor	₹10-12 lakh
DC Drive & Controller	₹5-6 lakh
Installation & Wiring	₹2-3 lakh
Total Initial Investment	₹17-21 lakh

5. Return on Investment (ROI)

Total Savings per Year: ₹6.56 lakh
Payback Period: ~3 years
Long-term Gains: After 3 years, pure savings on electricity costs.

6. Additional Benefits

✅ Better Performance Under Load – No voltage sag issues, stable operation.

✅ Reduced Downtime & Maintenance Costs – No rotor windings, no capacitor bank needed.

✅ Eco-Friendly & Sustainable – Reduced power wastage lowers carbon footprint.

7. Conclusion

Switching to a DC motor for the pellet mill results in 7-10% power savings, a payback period of ~3 years, and long-term operational efficiency. The investment in DC motor technology enhances productivity and reduces energy costs.