ABB ESP M1R Installation Instructions Manual page 18

connecting leads in the event of a short circuit. The fuse
to the ESP unit (F SPD ) should be lower than the
upstream supply fuse F S by a sufficient enough factor to
ensure fuse discrimination. As a general guide a factor of
at least 2 could be used (F SPD ≤ 0.5 F S ), where the
maximum fuse to the ESP unit required is 125 Amps (if
the supply fuse is 250 Amps or greater).
Refer to the fuse manufacturer's operating
characteristics to ensure discrimination, particularly
where an installation includes a mixture of types of fuse,
or of fuses and circuit breakers.
Live/phase connecting leads can be fused by either:
(a) installing appropriate high rupture capacity (HRC)
fuses or switchfuses in the connecting leads at the
supply end of the lead (See Figure 10), or
(b) installing up to a 125 Amp circuit breaker (MCCB or
type 'C'MCB).
Where the ESP unit is installed via an outgoing way
(3.5b earlier) this should incorporate up to a 125 Amp
HRC fuse or circuit breaker.
3/11 | Installation instructions for mains wire-in protectors