Short-Circuit/Earth-Fault Indicator - Siemens 8DJH Installation And Operating Instructions Manual
Medium-voltage switchgear
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Also See for 8DJH:
- Installation and operating instructions manual (174 pages) ,
- Operator's manual (2 pages) ,
- Installation and operating instructions manual (129 pages)
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Description
Mode of operation
24/121
Fig. 18:
Principle of gas monitoring with
ready-for-service indicator
For the ready-for-service indicator, a gas-tight measurement box is installed inside the
switchgear vessel.
A coupling magnet, which is fitted to the bottom end of the measurement box, transmits its
position to an armature outside the switchgear vessel through the non-magnetizable
switchgear vessel (magnetic coupling). This armature moves the ready-for-service indicator at
the operating front of the panel.
While changes in the gas density during the loss of gas, which are decisive for the dielectric
strength, are displayed, changes in the relative gas pressure resulting from temperature and
external pressure variations are not. The gas in the measurement box has the same
temperature as that in the switchgear vessel.
The temperature effect is compensated via the same pressure change in both gas volumes.
• The switchgear operates perfectly in a range between the rated filling level of 150 kPA and
the minimum functional level of 130 kPA.
• If the gas pressure falls below 130 kPA, the switchgear must not be operated anymore.
The ready-for-service indicator changes from the green area to the red area ("not ready for
service").
• If the ready-for-service indicator changes from the green area to the red area, the signaling
switch (option) changes its switching state.
Functional principle of the signaling switch
State of the ready-for-service indicator in
the green area
NC contact open and NO contact closed
①
Normally
②
Normally
closed
open contact
contact
7.11
Short-circuit/earth-fault indicator
The panels can optionally be equipped with short-circuit or earth-fault indicators in different
designs. Operating instructions and information on equipment features are available in the
respective manufacturing documentation.
Revision 05 • INSTALLATION AND OPERATING INSTRUCTIONS • 8DJH • 500-8067.9
①
Switchgear vessel (filled with SF
②
Measurement box
③
Magnetic coupling
④
Red indication: not ready for service
⑤
Green indication: ready for service
State of the ready-for-service indicator in
the red area
NC contact closed and NO contact open
gas)
6
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