Programmable Safety Controller SCR P
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The Minimum Distance Formula, as provided in EN 13855:
S = (K x T) + C
S
the Minimum Distance (in millimeters)
K
the EN 13855 recommended hand-speed constant (in millimeters per second), in most cases is calculated at 1600 mm/sec, but may vary
between 1600 to 2500 mm/sec based on the application circumstances;
not a conclusive determination; consider all factors, including the physical ability of the operator, when determining the value of K to be used.
T
the overall machine stopping response time (in seconds), from the physical initiation of the safety device to the final ceasing of all motion
C
the added distance due to the depth penetration factor equals 250 mm, per EN 13855. The EN 13855
C
factor may be reduced to 0 if the risk of
encroachment is eliminated, but the safety distance must always be 100 mm or greater
6.4.9 Safety Mat
The Safety Controller may be used to monitor pressure-sensitive safety mats and safety edges.
The purpose of the Safety Mat input of the Safety Controller is to verify the proper operation of 4-wire, presence-sensing
safety mats. Multiple mats may be connected in series to one Safety Controller, 150 ohms maximum per input (see
on p. 31).
The Safety Controller monitors the contacts (contact plates) and the wiring of one or more safety mat(s) for failures and
prevents the machine from restarting if a failure is detected. A reset routine after the operator steps off the safety mat may
be provided by the Safety Controller, or, if the Safety Controller is used in auto-reset mode, the reset function must be
provided by the machine control system. This prevents the controlled machinery from restarting automatically after the mat
is cleared.
Safety Mat Requirements
The following are minimum requirements for the design, construction, and installation of four-wire safety mat sensor(s) to be
interfaced with the Safety Controller. These requirements are a summary of standards ISO 13856-1, ANSI/RIA R15.06 and
ANSI B11.19. The user must review and comply with all applicable regulations and standards.
Safety Mat System Design and Construction
The safety mat system sensor, Safety Controller, and any additional devices must have a response time that is fast enough
to reduce the possibility of an individual stepping lightly and quickly over the mat’s sensing surface (less than 100 to 200
ms, depending on the relevant standard).
European Applications
Important:
The Safety Controller is not designed to monitor 2-wire mats, bumpers, or edges (with or
without sensing resistors).
WARNING:
Application of Safety Mats
— Safety Mat application requirements vary for the level of control reliability
or category and performance level as described by ISO 13849-1 and ISO 13856. Although Bernstein
Engineering always recommends the highest level of safety in any application, the user is responsible to
safely install, operate, and maintain each safety system per the manufacturer's recommendations and
comply with all relevant laws and regulations.
Do not use safety mats as a tripping device to initiate machine motion (such as in a presence-sensing
device initiation application), due to the possibility of unexpected start or re-start of the machine cycle
resulting from failure(s) within the mat and the interconnect cabling.
Do not use a safety mat to enable or provide the means to allow the machine control to start hazardous
motion by simply standing on the safety mat (for example, at a control station). This type of application
uses reverse/negative logic and certain failures (for example, loss of power to the Module) can result in a
false enable signal.
