Purpose
– Ensure power supply capability over a large temperature range
– Protect wires and cables in case of operational overload or short-circuit
– Additional limitation of let-through current and let-through
energy in case of short-circuit tripping in final circuit
– Disconnection and isolation of the system, also by ordinary people
– Special selectivity with respect to downstream circuit
breakers and upstream fuses
– Ensure a high availability of the electrical power supply
Function
ABB SMCB operate according to a voltage-independent principle.
They do not require an auxiliary source, neither for making /
breaking contact nor for the protective function. For overload
tripping, a thermostatic bimetal is used. As usual for circuit-
breakers, it is necessary to separate the main contacts in a time
less than 1ms by using a short-circuit “hammer trip” solenoid to
ensure effective short-circuit limitation. When the downstream
protection device has tripped because of a short-circuit, the
contact tips reclose automatically through a simple spring-type
system without requiring auxiliary energy.
If a short-circuit occurs between the S 750 (DR) and the
downstream circuit-breaker, another bimetal release enables
short-time delayed tripping. Both the selective release and the
overload release trip the mechanism and ensure that the contact
tips remain in the open position enabling isolating. The current
is limited and the arc is quenched as in the case of standard
circuit-breakers by means of quick contact opening by a “ham
mer trip” solenoid and quick build-up of the arc voltage in the
quenching chamber.
This operating principle achieves a particularly high selective behaviour
– the current-limiting selectivity.
In case of short-circuit in final circuits, the S 750 (DR) supports the downstream
circuit breaker and limits the energy and thus minimizes the im
pact on the whole installation and the feeding supply network.
This selective behaviour of the S 750 (DR) offers major advanta
ges compared to fuse-based technologies.
wechat/whatsapp:
+86-181-4410-0983
Email: kongjiangauto@163.com
Copyright © 2009 - 2024 Cld , All Rights Reserved K-JIANG All rights reserved