Siemens SENTRON - Page 76

Glossary
Selectivity for 3VA molded case circuit breakers
76 Configuration Manual, 08/2016, A5E03603181010-01
L release
Inverse-time delay over-current release as overload current protective device
LSI protective function
The LSI protective function is a combination of multiple release types. Circuit breakers with
LSI protective function have the following releases:
● Inverse-time delay over-current release (L release) as overload current protection
● Electronic short-time delay over-current release (S release) for delayed short-circuit
protection
● Instantaneous electromagnetic over-current release (I release) for instantaneous short-
circuit protection in the event of a dead short-circuit
Over-current
Current that exceeds the rated current as defined by IEC / DIN EN 60947-1, 2.1.4
Overload
Operating conditions in an electrically undamaged circuit which cause an over-current as
defined by IEC / DIN EN 60947-1, 2.1.7
Overload current
Over-current that flows in an electrically undamaged circuit as defined by
IEC / DIN EN 60947-1, 2.1.8
Prospective current Ip
The (prospective) current that would flow if the circuit breaker were to be replaced by a
conductor with negligible impedance. The prospective current expresses the value of the
short-circuit current that would flow without the circuit breaker.
Rated current In
The rated current for circuit breakers is equivalent to the rated uninterrupted current (I
u
) (see
4.3.2.4 of IEC 60947-1) and to the conventional free-air thermal current (I
th
).
Rated operational current Ie
The rated operational current of a device is specified by the manufacturer and is related to
the rated operational voltage, the rated frequency, the rated duty, the utilization category and
the enclosure type (if applicable).