Siemens siprotec 7SA6 User Manual page 20

Introduction
Power Supply
1-4
A battery backed clock is always provided and can be synchronized via a
synchronization signal with IRIG-B (GPS via satellite receiver) or DCF 77.
Additional interface modules provide the option to carry out further communication
protocols.
The 7SA6 can be supplied with any of the common power supply voltages. Transient
dips of the supply voltage which may occur during short-circuit in the power supply
system, are bridged by a capacitor (see Technical Data, Sub-section 10.1.2).
7SA6 Manual
C53000-G1176-C133-1