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Functional principle of the arc fault protection system DEHNshort

supply from transformer
UPS: Uninterruptible power supply
type 1 surge arrester L1-L3: Busbar
(e.g. DEHNventil )
®
detection device
+24 V
UPS 0 V DEHNshort
POWER
ERROR
T1 T2 T3 T4
current detection S1 IL1
S2 IL2
S3 IL3
S4 Io
QD
BI1
BI2 HSO1
BO1 HSO2
SET
Off
circuit breaker DSRT DD CPS ....
ARC PROTECTION
optoelectric
sensor DEHN DSRT PS
L1
quenching device
optoelectric Kurzschließereinheit fibre optic
sensor DEHN DSRT PS Quenching Device cable
L2
quenching device
optoelectric Kurzschließereinheit
sensor DEHN DSRT PS Quenching Device
L3

The overcurrent and light emission resulting from to a voltage drop and quenches the arc fault within
an arc fault are detected with the help of current a few milliseconds. The resulting short-circuit current
transformers and sensors. The current transformers activates the incoming circuit breakers.
are situated upstream of the incoming circuit breaker
and have to be protection transformers to reliably If selectivity is ensured by time grading, the trip
exclude saturation effects. To detect the light, either command activates the shunt releases to quickly dis-
optoelectronic or fibre optic sensors are used. The connect the part of the switchgear assembly where
sensor signals are linked logically in the electronic the arc fault occurred. The switchgear assembly can
detection devices and immediately activate the be recommissioned after the fault has been rectified,
quenching devices and all incoming circuit breakers the quenching devices have been replaced and the
in arc fault situations. The bolted short-circuit leads arc fault protection system has been reset.

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