Rockwell Automation 442L SC300 Safety Sensor User Manual - Manual (Page 21)

Rockwell Automation Publication 10000202762 Ver 00 - January 2012 19
Chapter 4 Mounting
Safety distance if OSHA and ANSI are applicable
If OSHA and ANSI are applicable, the safety distance depends on:
• Stopping/run-down time of the machine or system
(The stopping/run-down time is shown in the machine documentation or must be
determined by taking a measurement.)
• Response time of the entire protective device (SC300: 20 ms)
• Reach or approach speed
• Other parameters that are stipulated by the standard depending on the application
How to calculate the safety distance D
s
if OSHA and ANSI are applicable:
Note The following calculation shows an example calculation of the safety distance.
Depending on the application and the ambient conditions, a different calculation may be
necessary.
Calculate D
s
using the following formula:
D
s
= H
s
× (T
s
+ T
c
+ T
r
+ T
bm
) + D
pf
Where …
D
s
= The minimum distance in inches (or millimetres) from the hazardous point to the
protective device
H
s
= A parameter in inches/second or millimetres/second, derived from data on
approach speeds of the body or parts of the body. Often 63 inches/second
(1600 mm/second) is used for H
s
.
T
s
= Stopping/run down time of the machine tool measured at the final control
element
T
c
= Stopping/run-down time of the control system
T
r
= Response time of the entire protective device after light path interruption
(SC300: 20 ms)
T
bm
=Additional response time allowed for brake monitor to compensate for wear
Note Any additional response times must be accounted for in this calculation.
D
pf
= An additional distance added to the overall safety distance required. This value is
based on intrusion toward the hazardous point prior to actuation of the electro-
sensitive protective equipment (ESPE). Values range from 0.25 inches to 48 inches
(6 to 1220 millimetres) or more depending on application.
Example:
For vertical protection with an opto-electronic protective device with an
effective resolution finer than 2.5 inches (64 millimetres), D
pf
can be
determined approximately using the following formula:
D
pf
(inches) = 3.4 × (effective resolution – 0.276), but not less than 0.