Section 1: Introduction; Current Transformer Circuits; External Resistors; Fibre Optic Communication - Siemens 7SR224 Technical Manual

Section 1: Introduction

This manual is applicable to the following relays:
7SR224 Directional Overcurrent and Directional Earth Fault Recloser Control Relay
The 7SR224 relay integrates the protection and control elements required to provide a complete recloser control
relay.
The 'Ordering Options' Tables summarise the features available in each model
General Safety Precautions
1.1

Current Transformer Circuits

!
The secondary circuit of a live CT must not be open circuited. Non-observance of this precaution can result in
injury to personnel or damage to equipment.
1.2

External Resistors

!
Where external resistors are fitted to relays, these may present a danger of electric shock or burns, if touched.
1.3

Fibre Optic Communication

!
Where fibre optic communication devices are fitted, these should not be viewed directly. Optical power meters
should be used to determine the operation or signal level of the device.
1.4

Front Cover

!
The front cover provides additional securing of the relay element within the case. The relay cover should be in
place during normal operating conditions.
1.5

Front Fascia

!
For safety reasons the following symbols are displayed on the fascia
©2010 Siemens Protection Devices Limited
7SR224 Argus Description of Operation
Chapter 1 Page 6 of 70