"The computer thinks the cable runs 300 meters in a straight line. But look." He pointed to the map. "The real cable has to cross the rail spur, go around the acid storage tank, and dip under the cooling pond. The actual length is 410 meters."
A comprehensive calculation sheet typically includes input sections for system parameters and output sections for the final recommended size. Key data points often found in these sheets include: Free Cable Sizing Calculator BS 7671 - ELEK Software cable size calculation sheet
| Description | Symbol | Value | Unit | Formula / Reference | | :--- | :--- | :--- | :--- | :--- | | | | | | | | Connected Load | $P$ | 55 | kW | Input | | System Voltage | $V$ | 415 | V | Input | | Power Factor | $\cos \phi$ | 0.85 | - | Input | | Load Current | $I_b$ | 90.2 | A | $P / (\sqrt3 \times V \times PF)$ | | 2. Installation Conditions | | | | | | Max Ambient Temp | - | 40 | $^\circ C$ | Input | | Derating Factor (Temp) | $K_1$ | 0.91 | - | IEC Table | | Derating Factor (Group) | $K_2$ | 0.80 | - | IEC Table | | Total Derating Factor | $K_total$ | 0.73 | - | $K_1 \times K_2$ | | 3. Cable Selection | | | | | | Required Capacity | $I_req$ | 123.6 | A | $I_b / K_total$ | | Selected Cable Size | - | 35 $mm^2$ | - | Manufacturer Table | | Cable Rated Current | $I_z$ | 140 | A | $I_z > I_req$ (OK) | | 4. Voltage Drop | | | | | | Cable Length | $L$ | 80 | m | Input | | Volt Drop / Amp / Meter | - | 1.1 | mV/A/m | Data Sheet | | Total Voltage Drop | $\Delta V$ | 7.94 | V | $\fracI_b \times L \times mV/A/m1000$ | | Voltage Drop Percentage | $% V_d$ | 1.91% | % | $(\Delta V / V) \times 100$ | | Status | | PASS | | (Limit is 5%) | "The computer thinks the cable runs 300 meters
A=I⋅L⋅106K⋅ΔVcap A equals the fraction with numerator cap I center dot cap L center dot 10 to the sixth power and denominator cap K center dot cap delta cap V end-fraction Where: = Current (A) = Length (m) = Conductivity constant (Copper ≈is approximately equal to The actual length is 410 meters
A standard calculation sheet follows a sequential logic to determine the final cable size.
Ramesh sat at his metal desk, a relic from the 1980s, and pulled a well-worn manila folder from the drawer. On it, scrawled in fading ink, were the words:
Priya shivered.