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Earth Fault Loop Impedance with Safety Generator
Former Community Member
Do I take this into consideration? If so how do I size wire in a building with a safety generator? What is my "Ze" when the supply switches from DNO to the safety generator? How do diesel generators behave during faults?
If you really think that there are 2 options: one is a much larger generator than you need, say 1MVA for a 100 kVA supply. This is very expensive. The second option is to understand that the likely risk of supply failure is very small, much less than a fault at the same time. This means that having any supply is better than nothing, so you accept that a fault could occur but is very unlikely. Simple risk assessment to use the modern term. If an MCB fails to open what is the risk? Very small as the power available is also small. This is very important to understand.
If you really think that there are 2 options: one is a much larger generator than you need, say 1MVA for a 100 kVA supply. This is very expensive. The second option is to understand that the likely risk of supply failure is very small, much less than a fault at the same time. This means that having any supply is better than nothing, so you accept that a fault could occur but is very unlikely. Simple risk assessment to use the modern term. If an MCB fails to open what is the risk? Very small as the power available is also small. This is very important to understand.
