Lexicon DIY-Knowledge - Earth-leakage circuit-breaker (e.l.c.b.), residual-current-operated circuit breaker (r.c.c.b)

Earth-leakage circuit-breaker (e.l.c.b.), residual-current-operated circuit breaker (r.c.c.b)

FI-Schutzschalter, Fehlerstromschutzschalter

Interruptores de seguridad FI

Disjoncteur de protection FI

Switch which disconnects the circuit by electro-mechanical means if, for exmple, an insulation defect makes a fault current flow through the tool operator.

The fault current or leakage current is detected by a comparative measurement of the forward and reverse current in the power consumer. If the reverse current is not equivalent to the forward current, the earth-leakage circuit breaker is activated. This happens so quickly that the operator is adequately protected.

Earth-leakage circuit breaker (principle)
A Safe operation conditions, insulation
in order: no leakage current is flowing
through operator I₁ = I₂.
B Insulation damage: some of the
current is flowing through the operator
I₂ is reduced by I_F and is smaller than I₁
I₁ ≠ I₂. Earth-leakage circuit breaker
disconnects.
stated in mm.
1 measurement of I₁
2 measurement of I₂
3 circuit breaker (disconnects if there
is a variation between I₁ and I₂)
4 power consuming device (e. g. a motor)
I₁ current to consumer
I₂ current returning from consumer
IF leakage current
MP conductor
0 zero conductor (earth)