Siemens SENTRON 3VA1, Руководство пользователя

Страница: 52 / 676

Description
2.3 Technical details
3VA molded case circuit breakers with IEC certificate
50
Manual, 03/2019, A5E03603177010-03
Double-rotary contact system
To achieve excellent current limiting, the 3VA molded case circuit breakers are equipped
with a rotary double-contact system that opens dynamically - on its own - above the specified
disengaging currents, on the principle of magnetic repulsion, before the expected peak value
of the short-circuit current is reached. These limits have been coordinated and optimized to
suit the overall device characteristics. This substantially reduces the thermal and mechanical
loading on the molded case circuit breaker and the electrical installation.
①
Fixed contacts
②
Rotary contact system
③
Arc splitter chute
The switching pole cassettes are optimized for high breaking capacity, and their rotary
double-contact system design enables extremely good current limiting thanks to the build-up
of peak arc voltage generated at both contacts in the event of a short-circuit. This results in
significant limitation of the let-through energy I²t and the let-through current.
3VA molded case circuit breakers with a rated operational current I
n
> 630 A are equipped
with a single contact in order to optimize the mounting depth.