Servicing The Charging Circuit - Siemens MOBILETT Plus Manual

Capacitor-bank charging circuit

Servicing the charging circuit

DANGER
NOTE
Fig. 2
Closing this switch initiates discharge with a limited discharge current via a resistor pair -
including the two resistors R100 + R 101.
It is advisable that you connect a digital voltmeter to test points "CAP POS" and "CAP
NEG" on board D7 to follow the discharge process.
Perform servicing tasks in the charging circuit and on the capacitor bank only after com-
plete discharge of the capacitor bank!
The electrical energy stored in the capacitor bank for MOBILETTs is given by:
E =0.5 x (350 V)
In case of a short circuit, the energy released is equivalent to that set free by a one - ton
vehicle colliding with a wall at a speed of about 13.5 mph (22 kph)!
It is therefore necessary to expressly mention here that even a residual voltage of 10 V in
the capacitor bank is sufficient in case of a short circuit, such as due to placing a screw-
driver across the plus and minus terminals of the capacitor bank, to melt the metal shaft of
the screwdriver!
Siemens-Elema AB
Solna, Sweden
For safety reasons, before beginning servicing tasks in the charging circuit and in
the capacitor bank, the capacitor bank must be fully discharged!
Never work with the system open if the capacitor is charging or
has just been charged.
The capacitor bank may still be charged even if the system is
switched OFF and the mains cable is disconnected.
Life-threatening electric shock hazard exists.
See Chap. 1 "Safety information and protective measures".
The discharge procedure can be initiated manually
with service switch "S10" independently of whether the
unit is switched on or off.
S10
x 0.3 F = 18 375 Ws = 18.375 kWs
2
Register 6 SPR8-215.850.02
Rev. 01 01.02
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