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3RT1/3RH1 contactors
SIRIUS System Manual
3-12
GWA 4NEB 430 0999-02b
Auxiliary contacts and
built-on accessories
• A uniform and diverse range of auxiliary switches and accessories that
can be quickly upgraded and replaced is available for 3RT1 contactors up
to 45 kW for various applications.
• The 3RH auxiliary contactors can be extended to form variants with a
maximum of 8 poles using attachable 2 or 4-pole auxiliary switch blocks.
• Wiring kits with and without mechanical interlocking are available for put-
ting together 3RA contactor combinations for reversing and for star-delta
starting.
The accessories are described in detail in Section 3.4, "Accessories".
3.2.1 Actuating systems
Table 3-8: Actuating systems
3.2.2 Short-circuit protection of the SIRIUS contactors
Section 3.7, "Technical specifications", has information on short-circuit pro-
tection. Fuses and circuit breakers can be used as short-circuit protective
devices for the contactors.
The test criteria that apply in this case are stipulated by EN 60 947-4-1
(VDE 0660 Part 102).
Coordination types
Two types of assignment are defined in the standards that correspond to
two different levels of damage.
The following applies to both types of assignment:
In the event of a short-circuit, the short-circuit protective device used must
be able to disconnect the overcurrent that occurs both safely and success-
fully. Persons or other parts of the system must not be put at risk.
Coordination type 1
The load feeder (e.g. motor starter) can be inoperable after each short-circuit
disconnection. Damage to the contactor and the overload relay is permissi-
ble, but it is only possible to continue operation after defective devices have
been repaired or replaced.
AC coil:
• Ferromagnetic iron core (due to eddy current
losses)
• Adequate holding power
• Automatic reduction from high closing power to
low holding power
• Short switching times
DC coil:
• Solid parts are permissible
• Larger unit volumes (to achieve a tensile force
comparable to that of an AC coil)
• High holding power
• Closing power = holding power
• Longer switching times
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