commercial industrial zs mccb 3phase question TN-C-S.

[michaelw6]

Im specking a large 480a cable over 160m ive done cable calcs and come up with 2x 120mm 70c armored.
now Im trying to work out my max zs...with no avail.
my main ze is 0.17 but my mccb is saying max zs of 0.054 and my mccb will not trip... why is it so low?
its impossible to get my zs less than my ze?
any one who has experience with this please help where im going wrong or looking at something wrong here?!
cheers

 

[Leesparkykent]

What make is the MCCB?

 

[michaelw6]

Schneider 500a

 

[Leesparkykent]

vigirex relay to operate shunt trip on the MCCB which can be adjusted accordingly.

 

[Deleted member 26818]

Either obtain another MCCB, or use an RCD for earth fault protection.

 

[michaelw6]

ok so that my only options?

 

[michaelw6]

ill look this up cheers

vigirex relay to operate shunt trip on the MCCB which can be adjusted accordingly.