Banner SC22-3E Safety Controller with Ethernet - Manual (Page 90)

10 Input Device and Safety Category Reference
For ease in finding information about them, the specific device types discussed are presented in the following order.
10.2 Protective (Safety) Stop on page 92
10.3 Interlocked Guard or Gate on page 93
10.4 Optical Sensor on page 98
10.5 Two-Hand Control on page 100
10.6 Safety Mats on page 103
10.7 Emergency Stop Push Buttons on page 106
10.8 Rope/Cable Pull on page 109
10.9 Enabling Device on page 112
10.10 Bypass Switches (Bypassing Safeguards) on page 114
10.11.1 The Muting Function on page 116
Follow the device manufacturer’s installation, operation, and maintenance instructions and all relevant regulations. If there is
any question about the device(s) that are to be connected to the Safety Controller, contact a Banner Applications Engineer for
assistance.
10.1 Safety Circuit Integrity and ISO 13849-1 (EN954-1) Safety Circuit
Principles
Safety circuits involve the safety-related functions of a machine that minimize the level of risk of harm. These safety-related functions can
prevent initiation, or they can stop or remove a hazard. The failure of a safety-related function or its associated safety circuit usually
results in an increased risk of harm.
The integrity of a safety circuit depends on several factors, including fault tolerance, risk reduction, reliable and well-tried components,
well-tried safety principles, and other design considerations.
Depending on the level of risk associated with the machine or its operation, an appropriate level of safety circuit performance (i.e., integri-
ty) must be incorporated into its design. Standards that detail safety performance levels include ANSI/RIA R15.06 Industrial Robots, ANSI
B11 Machine Tools, OSHA 29CFR1910.217 Mechanical Power Presses, and ISO 13849-1 (EN954-1) Safety-Related Parts of a Control
System.
10.1.1 Safety Circuit Integrity Levels
Safety circuits in International and European standards have been segmented into categories, depending on their ability to maintain their
integrity in the event of a failure. The most recognized standard that details safety circuit integrity levels is ISO 13849-1 (EN954-1), which
establishes five levels: Categories B, 1, 2, 3, and the most stringent, Category 4.
In the United States, the typical level of safety circuit integrity has been called “control reliability.” Control reliability typically incorporates
redundant control and self-checking circuitry and has been loosely equated to ISO 13849-1 Categories 3 and 4 (see CSA Z432 and ANSI
B11.19).
If the requirements described by ISO 13849-1 are to be implemented, a risk assessment must first be performed to determine the appro-
priate category, in order to ensure that the expected risk reduction is achieved. This risk assessment must also take into account national
regulations, such as U.S. control reliability or European “C” level standards, to ensure that the minimum level of performance that has
been mandated is complied with.
SC22-3/-3E Safety Controller Instruction Manual
90 www.bannerengineering.com - tel: 763-544-3164 P/N 133487 rev. C