7SR210 & 7SR220 Applications Guide
© 2013 Siemens Protection Devices Limited Page 15 of 48
2.4 Arc Flash Detection (50AFD)
The overcurrent setting should be set above maximum load current and below the minimum expected arc fault
current.
Optical sensor location should be arranged to provide full coverage of the protected chambers. See 7XG31
technical documentation.
Sensor inputs are configured in Zones to provide the required tripping. i.e. the line circuit breaker alone should be
tripped for arc faults in the cable termination and CT compartment. The whole busbar must be cleared for arc
faults which cannot be identified as being on the line side of the circuit breaker.
Overcurrent supervision can only be applied if the arrangement ensures that current will be measured for all arc
faults. In Figure , Zone 2 can only be supervised by current if the feeders are radial and cannot supply fault
current with CB A open. Arc sensor pickup can be transferred between relays using IEC 61850 GOOSE allowing
Zone2 50AFD to be duplicated in all relays.
Zone1
Zone2
A
Figure 2.4-1 Arc Flash Detection
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