When we use air circuit breaker, it has O/L protection ,time delay SC protecti

When we use air circuit breaker, it has O/L
protection ,time delay SC protection, Instataneous SC
protection & ground fault protection. They all have some
setting range. But what is the suitable/allowable setting
for the above protection which will be safe for the
equipment?
For example-O/L protection setting have a range of
(0.4,0.45,0.5,0.55,0.6,0.65,0.7,0.8,0.9,1.0)xIn

Time delay SC protection have a range of
(1.25,1.5,2,3,4,6,8,10,12)xIn
Time delay setting is 0.02,0.1,0.2,0.3,0.4

Instataneous setting is fixed to 20xIn

Gound fault setting is given 100A,300A,600A,900A,1200A

This setting are for 2500A ACB.

So what will be the basic allowable setting for the above
protection? is there any formulae to calculate this<

Question Posted / pradeep123

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