(1) Description of Operation 7SR224
©2009 Siemens Protection Devices Limited Page 11 of 66
Located at the top rear of the case is a screw clamp earthing point, this must be connected to the main
panel earth.
2.3 FRONT COVER
With the transparent front cover in place the user only has access to the READ DOWN ▼ and
TEST/RESET► buttons, via blue push buttons, allowing all areas of the menu system to be viewed,
but preventing setting changes and control actions. The only ‘action’ that is permitted is to reset the
Fault Data display, latched binary outputs and LEDs by using the TEST/RESET button. The front
cover is used to secure the relay assembly in the case.
2.4 POWER SUPPLY UNIT (PSU)
The relay PSU can be directly connected to any dc supply via a suitably rated fuse from 30V dc to
220V dc.
In the event of the supply voltage level falling below the relay minimum operate level the PSU will
automatically switch itself off and latch out – this prevents any PSU overload conditions occurring. The
PSU is reset by switching the auxiliary supply off and on.
2.5 OPERATOR INTERFACE/ FASCIA
The operator interface is designed to provide a user-friendly method of controlling, entering settings
and retrieving data from the relay.
Figure 2.5-1 7SR224 with 12 Function Keys and 3 + 8 LEDs in E10 Case
NOTE: Transparent cover with pushbuttons not shown
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