The Power Calculation Formula
Conveyor drive power is calculated directly from the effective tension (the net force the drive applies to the belt) and belt speed:
P (kW) = Te (N) Γ v (m/s) / 1,000
The challenge is calculating Te accurately. This guide covers the practical calculation method for mine and plant conveyors.
Step 1: Calculate Main Resistance (Friction Component)
Tf = f Γ L Γ g Γ (mb + mm + 2 Γ mr)
Where:
- f = artificial friction factor (0.017 for well-maintained indoor; 0.020 for typical mine; 0.025 for poor maintenance or outdoor)
- L = conveyor length, centre-to-centre (m)
- g = 9.81 m/sΒ²
- mb = belt mass per metre (kg/m) β?from belt datasheet
- mm = material mass per metre = Q / (3.6 Γ v), where Q = capacity in t/h
- mr = rotating roller mass per metre (kg/m) β?estimate 8β?5 kg/m depending on belt width
Step 2: Calculate Lift Resistance
For inclined conveyors only:
Tl = mm Γ L Γ g Γ sin(ΞΈ)
For horizontal conveyors: Tl = 0. For downhill conveyors: Tl is negative (the loaded belt helps drive the system β?regenerative operation possible).
Step 3: Add Accessory Resistances
Each accessory adds resistance to effective tension:
| Accessory | Typical Resistance |
|---|---|
| Belt scraper (primary) | 500β?,500 N per scraper |
| Belt scraper (secondary) | 200β?00 N per scraper |
| Skirting (per metre) | 300β?00 N/m |
| Belt tripper | 1,000β?,000 N |
| Troughing transition zones | 200β?00 N each |
Worked Example
| Parameter | Value |
|---|---|
| Capacity Q | 800 t/h iron ore |
| Belt speed v | 3.0 m/s |
| Conveyor length L | 400m |
| Inclination | 8Β° upward |
| Belt mass mb | 22 kg/m (EP400/3, 8+4mm covers, 1,200mm wide) |
| Material mass mm | 800 / (3.6 Γ 3.0) = 74 kg/m |
| Roller mass mr | 12 kg/m (estimated) |
| Friction Tf | 0.020 Γ 400 Γ 9.81 Γ (22+74+24) = 94 kN |
| Lift Tl | 74 Γ 400 Γ 9.81 Γ sin(8Β°) = 40 kN |
| Accessories | ~3 kN (2 scrapers + skirting) |
| Total Te | 94 + 40 + 3 = 137 kN |
| Drive power P | 137,000 Γ 3.0 / 1,000 = 411 kW |
| With 20% margin | 411 Γ 1.2 = 493 kW β?select 500 kW motor |
π‘ Quick Estimate Method
For a rough preliminary estimate without full calculation: P (kW) β?Q (t/h) Γ L (km) Γ 0.06 for flat conveyors. Add Q Γ H Γ 0.003 for the lift component (H = height in metres). Example: 800 t/h, 400m, 8Β° incline (H=56m): P β?800Γ0.4Γ0.06 + 800Γ56Γ0.003 = 19.2 + 134 = 153 kW per 100m equivalent. Full calculation gives 411kW β?showing the quick estimate is conservative. Always do the full calculation for motor selection.
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