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Preparations for use
4.1 Notes for system integrators
• There must be a checkback signal for each of the the circuit breaker statuses CLOSED and
OPEN. The checkback signals must occur promptly, typically within a second.
• Provide time-overcurrent protection.
• Under no circumstances may the circuit breaker be electrically or mechanically externally
closed. A mechanical interlock of the manual ON command at the circuit breaker prevents
destruction of the converter as a result of an uncoordinated switch-on operation.
• In the event of external tripping of the circuit breaker, prevent the converter from shutting
down with unattributable follow-up messages. Therefore, ensure that the converter is
definitively switched to current-free with a "leading contact". This must happen before the
main contacts of the circuit breaker open. A corresponding message is also generated by the
converter open-loop controller ("external tripping of circuit breaker").
• Many circuit breakers do not have a mechanically leading contact. You can implement the
contact in various ways:
– If you are using a digital over-current relay, you must use it to detect all shutdown
– The voltage at the undervoltage coil is queried via an optocoupler. The output of the
Lack of intrinsic device protection for the circuit breaker
If the fuseless version of the converter is being used and the circuit breaker does not have any
additional intrinsic device protection, this can result in damage to the power unit.
Ensure that the circuit breaker has additional intrinsic device protection. The intrinsic device
protection must be switched off within 100 ms of a short-circuit current at the latest.
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conditions of the circuit breaker internally and externally (e.g. Buchholz fault). You must
program two tripping contacts with equivalent functions. One tripping contact is wired to
the "leading contact" input of the converter. The second tripping contact is wired to the
undervoltage release of the circuit breaker.
optocoupler is wired to the "leading contact" input of the converter. We recommend using
a Phoenix ST-OE 3 optocoupler with 24 V short-circuit-proof DC voltage output. The exact
type will depend on the auxiliary voltage of the switchgear (input data of the
optocoupler).
3rd Party LCI Control Upgrade
Operating Instructions, 02/2022, A5E31872818
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