Knowing the device’s power and voltage, how do I determine the size of the wire?
Thread Content
The equipment has a power of 250 kilowatts and a voltage of 380 volts. Then s = 250 / (3 * 0.22 * 5) = 75 square meters. The number 3 indicates a 3-wire system; the current-carrying capacity of copper wires is 5A. Is this calculation correct? ?
Are you asking about the wire diameter or the wire length?
Calculate the current, and then use that current value to determine the size of the wire!
I’m calculating based on the wire diameter. Is that correct? ? ?
What you did was wrong. First of all, the wire diameter is not calculated; rather, an appropriate cable cross-section is chosen based on the current. The current calculation is as follows: I=250/(1.732*0.38*0.9)=422.05A. Therefore, for safety reasons, the size of the cable should be YJV-2(3*120+1*70)
Generally, it is above 90 kW; 1 mm2 is required per kW. For values over 220 kW, 1.2 mm2 is needed
Literacy tip: It is recommended that colleagues interested in this topic read the following text to the end and draw their own conclusions. 1. For the selection of cables for low-voltage equipment, the current must be calculated first; for 380V equipment, the current value is approximately twice the power value. 2. For the wiring layout density, in the case of multi-layer cable trays, the current-carrying capacity coefficient can be set at 0.55 (to account for a reduction in capacity). Other factors such as wiring through pipes, burial, and ambient temperature also have an impact, but it’s not very significant. 3. The low-voltage voltage drop must be calculated. If it is not satisfactory, the wire diameter should be increased ； (380V generally has a supply radius of around 300 meters; voltage drop needs to be taken into account at greater distances.) 4. For equipment with more than 5000 hours of operation, it is recommended to use an economic current value when selecting the power cable. 5. In response to the original poster’s question, why not choose a high-voltage motor? If low-voltage motors are used following the approach described above, several software programs will be unable to perform the calculations. By rough calculation, it is advisable to use 4 cables of 95 or 3 cables of 120 or more connected in parallel.
2(YJV-0.6-3X150+1x70)