Current Inputs; Voltage Inputs - Siemens 7SR21 Manual

The status of hand reset LEDs is maintained by a back up storage capacitor in the event of an interruption to the
d.c. supply voltage.
Standard Pushbuttons
The relay is supplied as standard with five pushbuttons. The buttons are used to navigate the menu structure and
control relay functions. They are labelled:
▲
▼
TEST/RESET►
ENTER
CANCEL.
NOTE: All settings and configuration of LEDs, BI, BO and function keys can be accessed and set by the user
using these keys. Alternatively configuration/settings files can be loaded into the relay using 'Reydisp Evolution'.
Function Keys/ LEDs (Optional)
Six additional programmable pushbuttons can be specified. These can be configured by the user to initiate
selected functions from the Control menu (INPUT CONFIG > FUNCTION KEY MATRIX).
Each pushbutton has an associated LED. LEDs can be programmed as hand or self reset and can be illuminated
as green, yellow or red (OUTPUT CONFIG > LED CONFIG).
Function keys can be used with Quick Logic.
2.6

Current Inputs

Four current inputs are provided in the 7SR21 relay and five inputs are provided in the 7SR22 relay
Current inputs are located on the Analogue Input module. Terminals are available for both 1A and 5A inputs.
Current is sampled at 1600Hz for both 50Hz and 60Hz 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 1600Hz.
NB: The Relay has a flat frequency response measuring harmonic currents up to and including the 50th Harmonic
but does not measure the content at the aliasing frequencies i.e. 800 Hz (16th harmonic) + 1600 Hz (32nd
harmonic) + 2400 Hz (48th harmonic).
2.7

Voltage Inputs

Four voltage inputs are provided in the 7SR22 relay.
Voltage inputs are located on the Analogue Input module.
Voltage is sampled at 1600Hz for both 50Hz and 60Hz system frequencies. Protection and monitoring functions of
the relay use fundamental frequency voltage measurement.
The waveform recorder samples and displays voltage input waveforms at 1600Hz.
©2010 Siemens Protection Devices Limited
Increases a setting or moves up menu.
Decreases a setting or moves down menu.
Moves right, can be used to reset selected functionality and for LED test (at
relay identifier screen).
Used to initiate and accept settings changes.
Used to cancel settings changes and/or move up the menu structure by one
level per press.
7SR21 & 7SR22 Argus Description of Operation
Chapter 1 Page 18 of 71