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Searchline Excel Plus & Edge™ – Safety Manual
1 Introduction
This Searchline Excel Plus & Edge Safety Manual contains information, tables, examples and instructions that are crucial 
and relevant to all areas of system design, development, architecture, approvals, installation and commissioning, and to its 
ongoing safety, function and fitness for purpose once correctly installed and commissioned.
This manual should be read in conjunction with the References listed below, and in conjunction with any associated 
3rd-party manufacturer’s technical documents.
This manual should be used as a reference source when calculating maintenance and proof-testing periodicity, deferments 
and concessions, and when writing preventive maintenance and proof-testing procedures.
This manual may be used to calculate the probability of Searchline Excel Plus & Edge or component failure (PFD/PFH) for 
use in risk assessments and other scenarios.
1.1 References
IEC 61508: Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems (E/E/PE, or 
E/E/PES)
IEC 61508 has seven parts:
 Parts 13 contain the requirements of the standard (normative)
  Parts 47 are guidelines and examples for development and are thus informative.
Central to the standard are the concepts of risk and safety function. Risk is a function of the likely frequency of 
the hazardous event and the likely consequence and severity of an event. The risk can be reduced to a tolerable 
level by applying safety functions that may consist of E/E/PES and/or other technologies. While other technologies 
may be employed in reducing the risk, only those safety functions relying on E/E/PES are covered by the detailed 
requirements of IEC 61508.
2017M1220 Searchline Excel Plus & Edge Technical Manual
This manual contains all of the Searchline Excel Plus & Edge specifications, approvals, certifications and core technical 
information. It is intended for use by authorised technical personnel and OEMs, and is available in Technical English 
only.
2017M1225 Searchline Excel Plus Quick Start Guide
2017M1230 Searchline Excel Edge Quick Start Guide
These manuals are abridged and translated versions of the Searchline Excel Plus & Edge Technical Manual. They are 
intended for use by end users and operators.
1.2 Abbreviations
The following abbreviations have been used in this manual:
AC  Alternating Current
AIM  Analog Input Module
ß  Beta Factor – Common Cause Failure Factor for Undetected Dangerous Failures
ß
D
  Beta Factor – Common Cause Failure Factor for Detected Dangerous Failures 
DC  Direct Current
D
D
  Detected Dangerous Failures
DIM  Digital Input Module
D
u
  Undetected Dangerous Failures
I/O Input/Output
LED  Light Emitting Diode
mA Milliamp
NC  Normally Closed (circuit)
NO  Normally Open (circuit)
PFD  Probability of failure to perform its design function on demand
PFD
avg
  Probability of failure to perform its design function on demand (Averaged)
PFH  Probability of a dangerous failure per hour
POST  Power On SelfTest
PSU  Power Supply Unit
SFF  Safe Failure Fraction; a percentage of safe failures as compared to all failures
SIL  Safety Integrity Level
SIS  Safety Instrumented Systems
SPCO  Single Pole Change Over (Switch or Relay) 
TÜV  TÜV is a leading international body for the certification of safety and quality for products, services and management 
systems
UI  User Interface