Mode Of Operation Of The Capacitor Bank - Siemens MOBILETT XP Troubleshooting Manual

Basic functions

Mode of operation of the capacitor bank

Capacitor bank D972 generates the intermediate circuit voltage for the HV inverter, fila-
ment inverter, and anode starter modules.
Capacitor bank D972 is continuously charged by capacitor charger D952.
Capacitor bank D972 consists of 12 capacitors connected in parallel that deliver sufficient
energy to operate the inverter. Each capacitor is connected in series with a fast fuse.
Each capacitor has a capacity of 10 mF. The total capacity is 0.12 F. To facilitate handling
of these live components, the LEDs at the capacitors show the charge level > 40 V.
When the system is "OFF", the capacitors are discharged via three resistors (R3, R4, R5)
within 15-20 minutes.
The charging time of the capacitors varies depending on the charge level of the capacitor
bank. Around 7 to 9 seconds are required for charging empty capacitors.
The intermediate circuit voltage of the capacitor bank is monitored by D916 (CPU).
In the case of an error, the charging procedure is interrupted.
When replacing one or more capacitors of the capacitor bank, all capacitors must have a
voltage value of < 2 V to avoid outage of the fast fuses on D972.
Siemens AG
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