The short circuit current rating for 1 set of a copper cable is 40 kA. What will be the short circuit rating of the same cable for 3 sec?

Steps to Solve

1. Identify the given data

We know that the short circuit current rating for one set of the copper cable is 40 kA.

2. Understand the configuration

The question states that we need to determine the short circuit current rating for the same cable in a different configuration. The specific details of this configuration are not provided, but we will assume it relates to multiple sets of cables or adjustments in setup.

3. Determine the factors affecting short circuit current

Short circuit current ratings can depend on the number of cables in parallel, conductor size, material, and installation configuration. For example, if the cables are paralleled, the total short circuit current would increase accordingly.

4. Consider possible configurations

If the current configuration involves multiple sets (e.g., 2 or more cables in parallel), the new rating could be calculated as follows:

• For two sets, the short circuit current would be $40 \text{ kA} \times 2 = 80 \text{ kA}$.
• For three sets, the calculation would be $40 \text{ kA} \times 3 = 120 \text{ kA}$, and so forth.

5. Review the provided options

The options presented (73 A, 69 A, 13 A, 120 A) suggest that one of these is the anticipated current rating. Based on our reasoning and the common configurations, we should select the most plausible value.

6. Select the most appropriate answer

Given that configurations aren't specifically mentioned, we will lean toward recognizing that increasing the set increases the rating. A configuration resulting in 120 A from the original 40 kA actually fits well for certain setups.