Siemens SENTRON 3VL series, Системное руководство

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Application planning
6.5 Use in IT networks
3VL molded-case circuit breakers
System Manual, 03/2009, 110 0110 - 02 DS 01
71
6.5 Use in IT networks
Use of the 3-VL circuit breakers in IT networks
The 3VL circuit breakers up to frame size VL1250 have been tested in accordance with
IEC / EN 60947-2, Annex H (testing sequence for circuit breakers for IT systems) up to a
maximum (V
i
max.) voltage of 690 V AC. The switching capacities can be found in the
certificates of conformance testing (Page 346). The 3VL8 cannot be used in the IT network.
The SIEMENS SENTRON VL circuit breakers for system protection, optionally with thermal
overload and electromagnetic short-circuit releases, or electronic overcurrent trip units, are
suitable for use in IT networks. The circuit breakers also meet the requirements of the
IEC 60947-2 standard Annex H (DIN EN 60947-2, Annex H). The respective options are
required here, and the necessary safety clearances (ventilation clearances) must be
observed.
Selection criteria for circuit breakers
The devices are always dimensioned and selected independently of the relevant network
type. The circuit breaker is always selected in accordance with the maximum occurring
short-circuit current in the IT network. The device is selected in accordance with the relevant
I
cu
values of the 3VL circuit breaker.
Table 6- 3 I
cu
values depending on V
e
V
e
3VL1 3VL2 3VL3 3VL4 3VL5 3VL6 3VL7 3VL8
I
cu
at 240 V 65 kA 65 kA 65 kA 65 kA 65 kA 65 kA 65 kA 65 kA
I
cu
at 415 V 55 kA 55 kA 55 kA 55 kA 45 kA 50 kA 50 kA 50 kA
I
cu
at 690 V 8 kA 12 kA 12 kA 15 kA 20 kA 20 kA 20 kA 20 kA
The values in the above table apply provided one of the subsequent requirements is met:
●
The IT network is operated with a grounded neutral cable,
● the plant operator takes the necessary precautions to prevent the occurrence of a double
ground fault on the incoming or outgoing side of the circuit breaker.