Rockwell Automation 1394 SERCOS Interface Multi-Axis Motion Control System Installation Manual - Manual (Page 108)

Publication 1394-IN002B-EN-P — February 2004
A-4 Specifications and Dimensions
Circuit Breaker Specifications
While circuit breakers offer some convenience, there are limitations
for their use. Circuit breakers do not handle high current inrush as
well as fuses. The 1394 needs to be protected by a device having a
short circuit interrupt current rating of the service capacity provided or
a maximum of 100,000A.
If an upstream circuit protection device is rated for the overload
current and short circuit rating, a supplementary circuit protection
device (such as the 1492) can be used as the only 1394 branch circuit
protection device. The upstream fully rated device let-through must be
less than or equal to the 10 kA interrupt rating of the 1492.
The wiring interconnection in Figure A.1 and Figure A.2 provide
examples of the needed protection and follows UL and NEC codes.
Full compliance is dependent on final wiring design and installation.
Figure A.1
Circuit Protection under NEC 1999 110-10 (preferred fully rated devices)
Figure A.2
Circuit Protection under NEC 1999 110-10 (allowed but no longer preferred)
Required Protection
under 110-10 of
NEC 1999
Preferred Fully
Rated Breakers
Distribution
Blocks
Fully Rated
Fused
Disconnect
Fully Rated
Breaker
Drive Drive Drive
Fully Rated
Fused
Disconnect
Fully Rated
Breaker
Breakers Selected
for Device Protection
Fully Rated Short Circuit
Interrupt Capability
Required Protection
under 110-10 of
NEC 1999
Preferred Fully
Rated Breakers
Fully Rated
Fused
Disconnect
Fully Rated
Breaker
Breakers Selected
for Device Protection
Fully Rated Short Circuit
Interrupt Capability
Required Protection
under 110-10 of
NEC 1999
Allowed But
No Longer Preferred
Distribution
Blocks
Traditional
Current Limit
Fused
Disconnect or
Breaker
Rated for
Short Circuit
Available
Limiting to
Short Circuit
Rating of Down
Stream Breaker
Breakers Selected
for Device Protection
With Limited Short
Circuit Interrupt
Capability
Drive Drive Drive
Required Protection
under 110-10 of
NEC 1999
Allowed But
No Longer Preferred
Traditional
Current Limit
Fused
Disconnect or
Breaker
Rated for
Short Circuit
Available
Limiting to
Short Circuit
Rating of Down
Stream Breaker
Breakers Selected
for Device Protection
With Limited Short
Circuit Interrupt
Capability
Distribution
Blocks