Siemens 3VA1 100 A, Manual

Page: 127 / 532

Applications
3.2 Use of the 3VA1 breaker as a switch disconnector
3VA molded case circuit breakers
Manual, 04/2015, A5E03603177010-02
127
Isolating features
A switch disconnector isolates individual circuits or items of equipment so that maintenance
or repair work can be carried out. This is a health and safety requirement.
In compliance with IEC 60947-3, the symbol below is clearly displayed on the front panel of
switch disconnectors:
In accordance with the requirements of the standard regarding isolating function, the 3VA1
switch disconnector features:
● the switch disconnector symbol
● a correctly dimensioned isolating distance in the OFF position
When the switch disconnector handle is in the OFF position, the isolating distance between
the main contacts is guaranteed to meet the requirements stipulated by standards pertaining
to isolating features. This also applies when manual or motor operators installed on the
disconnector are in the OFF position.
Only when the disconnector is in this safe position can it be locked by various methods (e.g.
door mounted rotary operator, motor operator).
Making capacity
Switch disconnectors have a predefined rated making and rated breaking capacity. As a
result, loads are reliably switched on and off up to the specified breaking capacity.
Features
Switch disconnectors are primarily designed to conduct uninterrupted current up to the
magnitude of the permissible rated uninterrupted current I
u
.
Another important feature of these devices is their rated short-circuit making capacity I
cm
, as
this defines the capability of the switch disconnector to withstand dynamic and thermal
current loads. Current loads can reach very high values when the switch disconnector makes
on a short circuit. Switch disconnectors are designed to withstand these short-circuit currents
without sustaining damage up to the value of their rated short-circuit making capacity.