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If PSM is 5 and peak up current is 7A then fault current is
30A
35A
5A
5A
35A
Given: Plug Setting Multiplier (PSM) = 5, Pickup Current (IpickupтАЛ) = 7A
Plug Setting Multiplier (PSM) = 5, Pickup Current (IpickupтАЛ) = 7A
PSM=PlugSetting(IpтАЛ)FaultCurrent(IfтАЛ)тАЛ
Define the relationship
The Plug Setting Multiplier (PSM) is defined as the ratio of the actual fault current to the pickup current (or plug setting).
PSM=IpтАЛIfтАЛтАЛ
Rearrange the formula
To find the fault current IfтАЛ, rearrange the formula as IfтАЛ=PSM├ЧIpтАЛ.
IfтАЛ=PSM├ЧIpтАЛ
Calculate the fault current
Substitute the given values PSM=5 and IpтАЛ=7A into the equation.
IfтАЛ=5├Ч7=35A
B is correct because multiplying the Plug Setting Multiplier of 5 by the pickup current of 7A results in a fault current of 35A.
The PSM is a critical parameter in Inverse Definite Minimum Time (IDMT) relay coordination, directly determining the operating time of the relay on the time-current characteristic curve.