Siemens 7SR242 Duobias, Technical Manual

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©2015 Siemens Protection Devices Limited Chapter 7 Page 60 of 64
7.2 Binary Inputs
Each Binary Input (BI) can be programmed to operate one or more of the relay functions, LEDs or output relays.
These could be used to bring such digital signals as Inhibits for protection elements, the trip circuit supervision
status, autoreclose control signals etc. into the Relay.
Alarm and Tripping Inputs
A common use of binary inputs is to provide indication of alarm or fault conditions e.g. transformer Buchholz Gas
or Buchholz Surge conditions. The Binary Inputs can be mapped to LED(s), waveform storage trigger and binary
outputs.
The inputs can also be mapped as ‘General Alarms’ – this allows user defined text to be displayed on the LCD
when the BI is energised. Inputs used in this way are programmed using:
INPUT CONFIG>INPUT MATRIX> General Alarm n – Assigned to BI.
INPUT CONFIG>GENERAL ALARMS> General Alarm n – 16 character string.
Where transformer outputs require high speed tripping, such as a Buchholz Surge, these should be wired to a
binary input to provide LED indication and also have a parallel connection wired to directly trip the circuit via a
blocking diode, see Figure 7-2:
Figure 7-2 Example of Transformer Alarm and Trip Wiring