OM226142 rev C
14
Picture 10 – Short circuit characteristic (By-pass not available)
2.2.4 IGBT bridge protection
The inverter current monitoring is carried out by the DC current transducer connected
upstream the inverter bridge. Therefore the control logic is able to distinguish an output
short circuit from an IGBT short circuit.
The behaviour of the inverter in case of short circuit on the load has been described at
2.2.3; the output current is limited and the IGBT bridge current doesn’t reach the protection
threshold.
In case of short circuit in the inverter bridge the DC input current increases immediately
and there’s no possibility of limitation but stopping the PWM.
In this case the alarm A24 – Current stop is activated and must be reset manually after
having verified the status of the semiconductors.
Picture 11 – IGBT bridge protection
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