Section 1: Introduction; Current Transformer Circuits; External Resistors; Fibre Optic Communication - Siemens 7SR242 Manual

Section 1: Introduction

This manual is applicable to the following relays:
•
7SR242 Multi-Function 2-Winding Transformer Protection Relay
The 7SR242 relay integrates the protection and control elements required to provide a complete transformer
protection.
The 'Ordering Options' Tables summarise the features available in each model.
General Safety Precautions

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.
!

External Resistors

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

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.

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.
©2010 Siemens Protection Devices Limited
7SR242 Duobias Description Of Operation
Chapter 1 Page 6 of 52