Calculation of the total incoming current for a control cabinet
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I heard from those who are more experienced that a wire with a cross-sectional area of 1 square meter can handle a current of 7.5A. Today, when I was wiring a control cabinet, I used wires with a cross-sectional area of 4 square meters. After seeing this, my boss asked me what the current flowing into the control cabinet was. Ugh, I really didn’t know. My principle when wiring is to use wires with as large a cross-sectional area as possible; after all, thinner wires aren’t as safe as thicker ones. Maybe my boss is considering the cost of wires and wants to save money~~, so he asked me to choose the appropriate thickness of wire based on the current required~~:( :( :( I hope those who are more experienced can help me figure out how to calculate the current flowing into a control cabinet???? This post was last edited by hbzy on 2007-12-6 at 17:00.]
The control circuit needs to calculate the power consumption of various components inside the control cabinet. The main circuit is calculated based on the load current being controlled.
Low-voltage power distribution design specifications: http://bbs.hcbbs.com/viewthread.php?tid=66023. Cable current-carrying capacity table: http://bbs.hcbbs.com/thread-7705-1-1.html. You can refer to the information above; in addition to what the moderator said, it is necessary to calculate the power consumption of each component within the control cabinet for the control circuits. The main circuit is calculated based on the load current being controlled. ”Additionally, it can be noted that the diameter can be increased to serve as a reserve for the backup power supply (backup air switch), as well as for temporary electrical loads.
Mnemonic for calculating the current-carrying capacity of wires (reposted). The current-carrying capacity of a wire is related to its cross-sectional area, as well as factors such as the material and type of the wire, the method of installation, and the ambient temperature. There are many influencing factors, making the calculation complex. Calculation of wire cross-sectional area and current-carrying capacity I. Current-carrying capacity of ordinary copper wires The safe current-carrying capacity of a wire is determined based on the maximum allowable temperature of the wire core, the cooling conditions, and the installation conditions. The safe current-carrying capacity of copper wires is generally 5~8 A/mm2, while that of aluminum wires is 3~5 A/mm2. The safe current-carrying capacity of copper wires is generally 5~8 A/mm2, while that of aluminum wires is 3~5 A/mm2. For example: the recommended safe current-carrying capacity for 2.5 mm2 BVV copper wires is 2.5×8A/mm2 = 20A; the recommended safe current-carrying capacity for 4 mm2 BVV copper wires is 4×8A/mm2 = 32A. II. Calculating the cross-sectional area of copper wires: Using the recommended safe current-carrying capacity of 5–8A/mm2, the upper and lower limits for the cross-sectional area S of the chosen copper wire can be calculated as follows: S = I / (5–8) = 0.125I – 0.2I (mm2). Here, S represents the cross-sectional area of the copper wire in mm2, and I represents the load current in amps. Estimating the current-carrying capacity of aluminum-insulated wires: Multiply 2.5 by 9, then subtract 1 from the result to get the appropriate value. Thirty-five times 3.5, pair them up and subtract 0.5. Thirty-five times 3.5, pair them up and subtract 0.5. If conditions change, a discount is applied; at high temperatures, copper upgrades at a 10% discount. Two, three, four roots pass through the tube; at 80%, 70%, 60% load, full current flow.
XJTZWKDPJ said it so well. As a beginner, I’ve learned something from this; thank you
The selection of wires involves calculating the current in the load, determining the appropriate wire size based on its current-carrying capacity, and also verifying it through thermal stability considerations. For wires in general control circuits (mainly copper wires), 1.5 is sufficient, but 2.5 gauge wires are typically used in current-carrying circuits; 4 square millimeter wires are chosen only when the circuit length is large. In the main circuit, estimation methods cannot be used; instead, the demand factor method or the binomial method must be employed for calculations.
I’ve learned that when installing cables, it is necessary to consider their current-carrying capacity and also leave some margin.