Calculate peak and average traction demand in minutes. Include efficiency, auxiliaries, duty, and diversity factors. Use results to size feeders, generators, and panels accurately.
| Scenario | Mass (kg) | Speed (m/s) | Accel (m/s²) | Grade (%) | Crr | Eff (%) | Aux (kW) | Units |
|---|---|---|---|---|---|---|---|---|
| Haul road, moderate uphill | 15000 | 6.0 | 0.35 | 3 | 0.020 | 88 | 2.0 | 1 |
| Soft surface, low speed | 12000 | 3.5 | 0.20 | 1 | 0.045 | 85 | 1.5 | 2 |
| Level surface, higher speed | 18000 | 8.0 | 0.10 | 0 | 0.015 | 90 | 3.0 | 1 |
Traction demand on construction sites varies with haul distance, stop frequency, and payload. Use representative operating speed and acceleration from telemetry or time-motion studies. Apply duty factor to reflect the portion of time the drive delivers near-peak torque. For mixed routes, calculate separate segments and size on the highest peak while checking average energy for fuel or battery planning. Include idle periods if auxiliaries run continuously.
Total tractive force is the sum of rolling, grade, acceleration, and aerodynamic terms. On rough surfaces, rolling resistance usually dominates at low speed, while grade dominates on ramps. At higher speeds, drag grows with velocity squared and can rapidly increase power. Small changes in Crr or grade can shift demand materially, so record surface condition and slope carefully. Update inputs after compaction or rain.
Peak kW informs feeder and generator capacity, while estimated current supports cable, breaker, and switchgear selection. Include drivetrain efficiency and auxiliary loads because they directly increase electrical input. Use a realistic power factor for drives and verify voltage at the point of connection, not only at the source, to account for voltage drop during acceleration.
Multiple vehicles or traction modules rarely accelerate at the same instant. Diversity factor lets you model coincident peaks without ignoring worst-case scenarios. For critical operations, keep diversity near 100% and add contingency margin. For fleets with dispatch control, you may justify a lower coincident factor, but document the operating rule and expandability needs. Consider future routing, heavier loads, and seasonal grade changes.
Start with conservative inputs, then refine using measured speed, slope, and current logs. Compare calculated mechanical power to manufacturer tractive-effort curves and rated motor power. If regenerative braking is present, treat downhill segments separately and never rely on regen for primary sizing. Recheck assumptions after surface changes, weather, or payload increases. Validate results with short on-site load tests.
Use peak demand with diversity for feeders and generators. Then verify the resulting peak current against cable ampacity and protective device ratings. Average demand is mainly for energy and operational cost planning.
Start with published ranges for the surface type, then adjust based on tire type, moisture, and compaction. If you have fuel or current logs, back-calculate Crr to match measured performance on a known grade.
Downhill motion can reduce or reverse the required tractive force. For electrical sizing, traction demand is not allowed to go below zero, but auxiliary loads still draw power. Regenerative braking, if available, should be evaluated separately.
No. Duty factor reduces peak demand to an average level over time for one unit or a group. Diversity factor reduces coincident peak demand across multiple units because they do not all hit peak simultaneously.
Use the combined efficiency of motor, drive, and transmission at the operating point. If you only have a nameplate, assume 85–92% for preliminary work and refine with manufacturer curves or test data.
It is a planning estimate based on kW, voltage, phase, and power factor. Real current can be higher during transient starts or if voltage drops. Confirm with drive specifications, starting method, and site power quality measurements.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.