Banner ES-UA-5A Instruction page 3

ES-UA-5A and ES-VA-5A E-Stop Safety Modules
An Emergency Stop Safety Module is used to increase the control
reliability of an emergency stop circuit. As shown in the hookup
drawings, the models ES-UA-5A and ES-VA-5A E-Stop Safety
Modules (the Safety Modules) are designed to monitor a 1-
channel or 2-channel E-stop switch. A 2-channel E-stop switch
has two electrically isolated contacts.
Safety Circuit Integrity and ISO 13849-1 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., integrity) must be incorporated into its design. Standards that detail safety performance levels
include ANSI/RIA R15.06, ANSI B11 and B11.19, OSHA 29CFR1910.217, and ISO 13849-1 (EN954-1).
Safety Circuit Integrity Levels
Safety circuits in international and European standards are segmented into categories, depending on their ability to
maintain their integrity in the event of a failure. The most recognized of these standards 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.TR4).
If the requirements described by ISO 13849-1 are to be implemented, a risk assessment must first be performed to
determine the appropriate category, in order to ensure that the expected risk reduction is achieved. This risk assess-
ment must also take into account national regulations, such as U.S. control reliability or European "C" level standards,
to ensure that the minimum mandated level of performance is complied with.
WARNING . . . Safety Categories
The level of safety circuit integrity can be greatly impacted by the design and installation of the safety devices and
the means of interfacing of those devices. A risk assessment must be performed to determine the appropriate
safety circuit integrity level or safety category as described by ISO 13849-1 (EN 954-1) to ensure that the
expected risk reduction is achieved and that all relevant regulations and standards are complied with.
P/N 122365 rev. C Banner Engineering Corp. - Minneapolis, MN USA - www.bannerengineering.com
Overview
Figure 1: Features and terminals
Tel: 763.544.3164
S31 S32 S33 S34 S32 S35
A1 A2 B1 B2 S11 S12 S21 S22
13 14 23 24 33 34 43 44
Y30 Y31 Y32 Y35 51 52
3