Technical information

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XT1D
XT3D
XT4D
1SDC210033D0202
The switch-disconnector (or, in short, disconnector) is a device created from the corresponding
circuit-breakers (of which it features the same overall dimensions, versions, fastening mechanisms
and ability to be fitted with accessories).
The main function of these devices is to disconnect the circuit they are installed in. In the open
position, the disconnector disconnects and guarantees a sufficient insulation distance (between the
contacts) to assure safety and to prevent an electrical arc from striking.
Applications
Switch-disconnectors are generally used as:
Q general disconnectors of subswitchboards;
Q operating and disconnecting devices for lines, pan-assembliess or groups of equipment;
Q bus-ties;
Q general disconnecting devices for groups of machines;
Q general group disconnecting devices for motor operation and protection;
Q insulation of small tertiary distribution units.
Protection
A disconnector is unable to automatically break the short-circuit or overload current. For this rea-
son, each switch-disconnector must be protected on the supply side by a coordinated device that
safeguards it against short-circuits. The circuit-breaker able to act as a protection for each switch-
disconnector is indicated in the table below.
Category of use
(G2.11)
The CEI EN 60947-3 Standard defines the utilisation categories for disconnectors in accordance
with the table below. Tmax XT disconnectors comply with the AC21A, AC22A and AC23A utilisation
categories.
Class of use
Infrequent
operation
Frequent
operation
Typical applications
AC-21A AC-21B Control of resistive loads with overloads of modest entity
AC-22A AC-22B Control of mixed resistive and inductive loads with overloads of modest entity
AC-23A AC-23B Control of motors or other highly inductive loads
Switch-disconnectors
Main characteristics
Characteristics of switch-disconnectors
XT1D XT3D XT4D
Size
(G2.1)
[A] 160 250 250
Rated operating current in class AC21, Ie
(G.2.12)
[A] 160 250 250
Rated operating current in class AC22, Ie
(G.2.12)
[A] 160 250 250
Rated operating current in class AC23, Ie
(G.2.12)
[A] 125 200 200
Poles [Nr.] 3, 4 3, 4 3, 4
Rated service voltage, Ue
(G2.4)
(AC) 50-60Hz [V] 690 690 690
(DC) [V] 500 500 500
Rated insulation voltage, Ui
(G2.5)
[V] 800 800 800
Rated impulse withstand voltage, Uimp
(G2.6)
[kV] 8 8 8
Test voltage at industrial frequency for 1 min [V] 3000 3000 3000
Rated breaking capacity
in short-circuit, Icm
(G2.10)
(Min) Disconnector only [kA] 2.8 5.3 5.3
(Max) With automatic
circuit-breaker on supply side
[kA] 187 105 105
Rated short-time withstand current for 1s, Icw
(G2.9)
[kA] 2 3.6 3.6
Versions Fixed,
Plug-in
Fixed,
Plug-in
Fixed, Withdrawable,
Plug-in