Current Inputs; Binary Inputs; Figure 3-12 Binary Input Logic - Siemens 7SR45 Argus User Manual

3.10 Current Inputs

7SR45 self powered overcurrent and earth fault relay consists of 4 current inputs. The 3 current inputs are used
for measuring the phase currents and 1 current input is used for measuring the ground current.
Based on the ordering option, current inputs are available for 1 A and 5 A variants.
7SR45 self powered overcurrent and earth fault relay consists of 1 built-in Power Current Transformer (PCT) and
1 built-in Measuring Current Transformer (MCT) for each phase current input. 1 MCT is provided on the ground
current input.
The current is sampled at 800 Hz for both 50 Hz and 60 Hz system frequency. Protection and monitoring
functions of the relay use the fundamental frequency component to calculate the RMS value of current.
The primary CT ratio used for the relay instruments can be set in the CT/VT configuration menu.

3.11 Binary Inputs

The binary inputs (BI) are opto-couplers operated from a suitably rated DC power supply.
Each BI can be configured to perform one or more of the relay functions.
The status of BI can be viewed via LCD or Reydisp Evolution software.
Binary input can be configured to operate the binary output or impulse output.
Relays are fitted with 2 binary inputs. The user can assign any binary input to any of the available functions such
as inhibits, binary outputs, reset flags, and general alarms (INPUT CONFIG > INPUT MATRIX). Binary input can
also be mapped to operate the impulse output in the presence of CT power.
Pick-up (PU) and drop-off (DO) time delays are associated with each binary input. Where no pick-up time delay
has been applied the input may pick up due to induced AC voltage on the wiring connections (e.g. cross site
wiring). The default pick-up time of 20 ms provides AC immunity. Each input can be configured independently.
Each input may be logically inverted to facilitate integration of the relay within the user scheme. When inverted the
relay indicates that the BI is triggered when no voltage is applied. Inversion occurs before the PU and DO time
delay.
Binary inputs can be configured for instantaneous operation from 19 V DC power supply by setting of 0 ms PU
and 25 ms DO timers.
Each binary input can be assigned to any binary output. This allows the relay to provide panel indications and
alarms.
© 2017 Siemens Protection Devices Limited

Figure 3-12 Binary Input Logic

7SR45 Description of Operation
Chapter 1 Page 26 of 34