Current Inputs; Voltage Inputs; Binary Inputs - Siemens 7SR18 Solkor Manual

2.6

Current Inputs

Four current inputs are provided on the Analogue Input module. Terminals are available for both 1 A and 5 A
inputs.
The relay can be used for line differential, phase-fault and earth-fault protection.
Current is sampled at 1600 Hz for both 50 Hz and 60 Hz system frequencies. Protection and monitoring functions
of the relay use either the Fundamental Frequency RMS or the True RMS value of current appropriate to the
individual function.
The waveform recorder samples and displays current input waveforms at 1600 Hz.
The primary CT ratio used for the relay instruments can be set in the CT configuration menu.
The CT direction can be changed by Enabling the Phase Reversal setting which is provided on a per phase basis.
2.7

Voltage Inputs

Three voltage inputs are provided on the Analogue Input module on the 7SR181 Directional variant of the relay.
Voltage is sampled at 1600Hz for both 50Hz and 60Hz system frequencies. Monitoring functions of the relay use
fundamental frequency voltage measurement.
The primary VT ratio used for the relay instruments can be set in the CT/VT configuration menu.
2.8

Binary Inputs

The binary inputs (BI) are opto-couplers operated from a suitably rated power supply.
Relays are fitted with 3 binary inputs or 6 binary inputs depending on the variant. The user can assign any binary
input to any of the available functions (INPUT CONFIG > INPUT MATRIX).
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 programmed 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 energised when no voltage is applied. Inversion occurs before the PU & DO time
delay, see Figure 2.8-1.
Binary inputs can be configured for intentional operation from a 110/115 V rms a.c. power supply by setting of 0
ms PU and 25 ms DO timers. If additional pickup or drop-off time delays are required by the scheme logic, this
functionality can be achieved by programmable logic within the device. For AC operation, live and neutral wiring
should be routed as a pair in close proximity and limited to a length of less than 10 m.
Each input may be mapped to any front Fascia indication LED and/or to any Binary output contact and can also
be used with the internal user programmable logic. This allows the relay to provide panel indications and alarms.
Each binary input is set by default to be read when the relay is in both the local or remote condition. A setting is
provided to allow the user to select if each individual input shall be read when the relay is in the local or remote
condition in the INPUT CONFIG > BINARY INPUT CONFIG menu.
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7SR18 Description Of Operation
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