Answer :
Final answer:
The plug setting multiplier (PSM) of the relay is calculated as 0.5 by dividing the secondary current, which is 25 A (determined from the fault current and CT ratio), by the relay setting of 50.
Explanation:
The plug setting multiplier (PSM) of the relay can be calculated using the fault current, the relay setting, and the current transformer (CT) ratio. First, we determine the secondary current of the CT using the fault current and CT ratio, then divide by the relay setting to find the PSM.
The CT ratio given is 400/5, meaning for every 400 A on the primary side, there will be 5 A on the secondary side. With a fault current of 2 kA (2000 A), the secondary current (Is) is:
Is = Fault Current / (CT Primary / CT Secondary) = 2000 A / (400 A / 5 A) = 25 A
Next, we need to divide the secondary current by the relay setting to find the PSM:
PSM = Is / Relay Setting = 25 A / 50 = 0.5
Therefore, the PSM of the relay is 0.5.
