Answer :
Final answer:
The plug setting multiplier (PSM) for a relay with a fault current of 2 kA, a relay setting of 50%, and a CT ratio of 400/5 is calculated to be 10.
Explanation:
The question relates to the calculation of the plug setting multiplier (PSM) of a relay in an electrical engineering context. To calculate the PSM, you need to understand the relationship between the fault current, the relay setting, and the current transformer (CT) ratio.
In this scenario, the fault current is 2 kA (2000 A), the relay setting is 50%, and the CT ratio is 400/5. The first step is to determine the secondary fault current, which is the current that would be seen by the relay. This can be calculated using the primary fault current and the CT ratio as follows:
Secondary fault current = (Primary fault current) / (CT ratio) = 2000 A / (400/5) = 25 A
Now, the plug setting multiplier can be determined by dividing the secondary fault current by the product of the relay setting and the CT's secondary current:
Plug Setting Multiplier (PSM) = Secondary fault current / (Relay setting % * CT secondary current)
PSM = 25 A / (0.50 * 5 A) = 10
Therefore, the plug setting multiplier for the relay in this scenario is 10.
