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7 - 3
Siemens AG ⋅ May 1998
7.2.2 Checking the auxiliary voltage supply
The alarm of auxiliary voltage failure in the protection
device can be caused by a device failure as well as by
disturbances in the external wiring. It should be
checked whether
D auxiliary voltage can be measured with adaquate
magnitude and correct polarity,
D the ON/OFF switch for the integrated converter on
the front plate of the FE or behind the front plate
of the ZE is in ON position,
D the modules are correctly fitted and locked and
D the fuses in the power supply section of the FE
(module SAF) or ZE (module SV) have not blown.
The explanation of the LED indication of the power
supply module in the master unit is given in chapter
7.2.4.
7.2.3 Replacement of fuses
The power supply modules SV in the master unit and
SAF in the bay units are protected against short-cirĆ
cuit by fine-wire fuses.
For checking or replacement of these fuses, the
units' front plates has to be opened after loosening
the fixing screws.
The SV is located at the extreme right mounting place
in the subrack of the ZE (refer to Fig 2.2). This module
can be withdrawn from the subrack after switching
off the auxiliary voltage and loosening the module
lock).
The module SAF of the bay unit (refer to Fig 2.3) can
be withdrawn from the casing after removing the
front ribbon cable.
For easy removal of the modules the extraction tool,
which is part of the delivery, may be used.
Attention
Electrostatic discharges across the moduĆ
les' connectors, printed conductors and
connection pins have to be avoided by
previously contacting earthed metal parts.
i
Note
Even after disconnection of the power
supply or removal of modules dangerous
voltages may be present in the device
(capacitor storage)!
The withdrawn modules shall be placed vertically on
the laboratory table. The use of a conductive surface
(e.g. EMC-mat) is recommended for the modules in
order to avoid electromagnetic discharging via compoĆ
nents.
The location of the fuse element can be seen in Fig
7.1 and 7.2.
After checking the fine-wire fuses, the module is inĆ
serted into the casing. Care must be taken that the
module is fixed correctly and firmly contacted with
the rear-side plug connector.
Then the removed electrical connections have to be
re-established and the front cover closed. Please
note that the switch for the power supply SV in the
master unit is not accessible with closed front plate.
The device is switched ON. If the auxiliary voltage
failure continues to be indicated, then there must be
a failure or short-circuit in the internal power supply.
The power supply module should be sent to the facĆ
tory.
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