Section 1: Introduction; Current Transformer Circuits; 1.2 External Resistors; 1.3 Front Cover - Siemens 7SR11 Manual

Section 1: Introduction

This manual is applicable to the following relays:
•
7SR11 Overcurrent and Earth Fault Relay
•
7SR12 Directional Overcurrent and Directional Earth Fault Relay
The 'Ordering Option' 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 connected to the relay circuitry, these may present a danger of electric
!
shock or burns, if touched.

1.3 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.
©2012 Siemens Protection Devices Limited
7SR11 & 7SR12 Description Of Operation
Chapter 1 Page 7 of 76