How to Select an Earth Leakage Circuit Breaker

How to Select an Earth Leakage Circuit Breaker?  Please check below:

Rated current of 400A of the first level protection residual current operated circuit breaker, for example:

First level protection

Connecting wires:
Copper core plastic insulated conductor cross-sectional area is 50mm ²
Rated operating current: 250A
Rated residual operating current: 300mA ~ 500mA
Residual breaking time: 0.6s ≤ t ≤ 0.8s
The optional residual current operated circuit-breakers are:
TREF4-250/400 

Second level protection:

Connecting wires:
Copper core plastic insulated wire cross-sectional area is 4 ~ 16mm ²
Rated operating current: 100A, 80A, 63A, 40A
Rated residual operating current: 100mA ~ 300mA
Residual breaking time: 0.2s ≤ t ≤ 0.4s
The optional residual current operated circuit breakers are:
TREF4-250, TREF3-160 

Third level protection:

Connecting wires:
Copper core plastic insulated conductor cross-sectional area is 1.5 ~ 4mm ²
Rated operating current: 40A, 32A, 20A
Rated residual operating current: 30mA or less
Residual breaking time: t ≤ 0.1s or faster
The optional residual current operated circuit-breakers are:
TREF2-100, TREF1-63

Fourth level protection:

Connecting wires:
Copper core plastic insulated conductor cross-sectional area is 1 ~ 2.5mm ²
Rated operating current: 32A, 20A
Rated residual operating current: 10mA or less
Residual breaking time: fast action type
The optional residual current operated circuit breakers are:
TREF1-63,TRE2-50