Front Cover; Power Supply Unit (Psu); Operator Interface/ Fascia; Figure 2-1 7Sr24 With 3 + 16 Leds In E8 Case - Siemens 7SR242 Duobias Technical Manual

2.3

Front Cover

With the transparent front cover in place the user only has access to the
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 substation dc system rated from 30V dc to 220V dc.
In the event of the station battery 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 then on.
Typically the PSU is connected to the auxiliary supply via an external HRC fuse rated at 6A (BS88/IEC60259).
Isolation links may also be installed in accordance with user requirements.
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.
The fascia is an integral part of the relay. Handles are located at each side of the element to allow it to be
withdrawn from the relay case.
©2015 Siemens Protection Devices Limited
Figure 2-1 7SR24 with 3 + 16 LEDs in E8 Case
NOTE: Pushbuttons on cover not shown
Chapter 1) 7SR242 Duobias Description Of Operation
and TEST/RESET buttons,
Chapter 1 Page 16 of 60