11.98
Description
Siemens AG 6SE7087-6AC85-0AA0
ENGLISH
1-1
Common Rectifier Operating instructions
1 Description
1.1 Applicability
The common rectifier in the SIMOVERT Master Drives series is a power electronics device. From the three-
phase mains, it generates a dc network and is used as a dc supply unit for one or several units in the
SIMOVERT Master Drives inverter series with a dc link.
A three-phase mains is connected to the input. One or more inverters and a brake chopper can be connected to
the DC output. The total of the rated currents of the installed inverters may then exceed the rated current of the
common rectifier. It must however be ensured in the course of system planning that at no moment in time is the
total of DC load currents greater than the rated DC current of the common rectifier. Feedback to the mains is
not possible.
Refer to the technical data in Chapter 14 for details of voltage and current ranges.
1.2
Principle of operation
The common rectifier consists of a 6-pulse diode bridge for rectification of the dc network.
Precharging begins as from the point when the mains voltage is applied and is realised by resistors in the dc
branch. The precharging resistors are bypassed by relays when the dc link voltage exceeds a given power-on
threshold. Within the +10 and -15 % mains voltage tolerance, and if the rated ac-side voltage is chosen
correctly on selector switch S1 and S3 and if the maximum possible capacitive load is observed, precharging
takes place within one second. The maximum dc link capacitance of a group drive must not exceed that of a
single inverter whose rated current in the dc link corresponds to the rated current of the common rectifier.
Tapping of load current during precharging must be avoided!
Bypassing of the precharging resistors will be interrupted if the dc link voltage should drop below the off
threshold as the result of a mains power failure or extreme drops in the mains voltage. This prevents excess
currents as the result of charging of the dc link capacitors at too fast a rate when the mains voltage returns.
The common rectifier does not check for an earth fault at the output of a connected converter because the
precharging resistors adequately protect its freewheeling diodes against excess current.
Excess temperature of the power section, excess temperature of the precharging resistors, phase failure and
the electronic power supply are monitored. Monitoring triggers deactivation and a fault signal in the event of any
hazard. The output current is not monitored. Protection against excess currents must be ensured by suitable
dimensioning and operation of the connected inverters.
Use of a main contactor or a similarly functioning facility controlled by the fault signalling relay is necessary to
ensure safe and reliable operation of the common rectifier.
Fault signals are acknowledged by deactivating the mains voltage or the electronic power supply.
The on and off thresholds for bypassing the precharging resistors are defined by the setting of selector switch
S1 or S3 on module A23 (see Commissioning).
The power for the electronics is supplied externally via a 24 V DC input.
www
. ElectricalPartManuals
. com
