Section 1: Introduction; Current Transformer Circuits; External Resistors; Fibre Optic Communication - Siemens 7SR224 Description & Operation

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 C
URRENT
!
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 E
XTERNAL
!
Where external resistors are fitted to relays, these may present a danger of electric shock or burns, if
touched.
1.3 F
IBRE
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 F
RONT
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 F
RONT
!
For safety reasons the following symbols are displayed on the fascia
©2009 Siemens Protection Devices Limited
T C
RANSFORMER
R
ESISTORS
O C
PTIC OMMUNICATION
C
OVER
F
ASCIA
IRCUITS
(1) Description of Operation 7SR224
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