Prospective Fault Current

Question 1

Where is prospective fault current measured?

Answer 1

Measured at the mains because it has the lowest impedance value, low impedance value will give the highest fault current

Question 2

Why is a high fault current required

Answer 2

ensures protective device breaking capacity is larger than the fault current to allow the device to stop the flow of current in the event of a fault and not arc across the device

Question 3

Converting to 3ph?

Answer 3

value obtained is for a single phase supply, it must be multiplied by 3 for 3ph

Question 4

Why use the origin of supply?

Answer 4

Origin of the supply will give the highest fault current therefore if the entire installations protective devices can stop that value the entire installation will have a satisfactory breaking capacity

Question 5

What can the fault value be used to calculate?

Answer 5

Zs=Ze+r1+r2

Question 6

What can the fault value be used to calculate?

Answer 6

Zs=Ze+r1+r2