Technical information

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1SDC210033D0202
Class B - Circuit-breakers specifically designed for selectivity under short-circuit conditions
in relation to other protection devices installed in series on the load side, i.e. with an inten-
tional delay (which can be adjusted), applicable under short-circuit conditions. The short-
time withstand current is specified for these circuit-breakers (Icw).
A circuit-breaker belongs to category B if its Icw value exceeds:
Q
between 12In and 5kA, whichever is higher, for In)2500A;
Q
30kA for In>2500A.
G2.12 Utilisation category of non-automatic circuit-breakers
The utilisation category of non-automatic circuit-breakers establishes the type of condition
of use.
It is identified by two letters, which indicate the type of circuit in which the device may be
installed (AC for alternating current and DC for direct current), a two-digit number for the type
of load that can be controlled and an additional letter (A or B), which indicates the operating
frequency.
With reference to the utilisation categories, the product Standard establishes the current val-
ues the switch-disconnector must be able to break and interrupt under abnormal conditions.
The utilisation categories of non-automatic circuit-breakers are listed in the table below:
Nature
of the
current
Utilisation categories
Utilisation category
Typical applications
Frequent
operation
Infrequent
operation
Alternating
current
AC-20A AC-20B Connection and disconnection under no-load conditions
AC-21A AC-21B Connection and disconnection under no-load conditions
AC-22A AC-22B Resistive load operation including moderate overloads
AC-23A AC-23B
Mixed resistive and inductive load operation including
moderate overloads
Direct
current
DC-20A DC-20B Operation of motors or other highly inductive loads
DC-21A DC-21B Operation of resistive loads including moderate overloads
DC-22A DC-22B
Mixed resistive and inductive load operation including a
moderate overload (e.g. motors with shunt)
DC-23A DC-23B Operation of highly inductive loads
G2.13 Electrical life
The electrical life of a device indicates the number of on-load operating cycles and the resist-
ance of the contacts to electrical wear under the conditions specified in the relative product
Standard.
G2.14 Mechanical life
The mechanical life of a device indicates the number of no-load operating cycles (each
operating cycle consists of a closing and opening operation) the device is able to carry out
without overhauls or replacement of mechanical parts (routine maintenance is allowed).
G2.15 Dissipated power
This is the loss, caused by the joule effect, due to the electrical resistance of the circuit-
breaker poles; the energy lost is dissipated in heat.
G2.16 Utilisation categories for operating parts
The utilisation categories given in the table are considered to be standard (CEI EN 60947-5-1).
Type of current Class
Typical applications
AC
AC-12
Control of resistive loads and electronic loads with insulation obtained
by use of optoinsulators
AC-13
Control of electronic loads with insulation transformer
AC-14
Control of small electromagnetic loads ()72VA)
AC-15
Control of electromagnetic loads (>72VA)
DC
DC-12
Control of resistive loads and electronic loads with insulation obtained
by use of optoinsulators
DC-13
Control of electromagnets
DC-14
Control of electromagnetic loads with economiser resistors in the circuit