European Safety Distance Formula - Allen-Bradley GuardShield 440L-T2KA series Installation Instructions Manual

GuardShield Type 2 Safety Light Curtain
Dpf Depth penetration factor. It is an added distance to allow
for how far into the protective field an object, such as a
finger or hand, can travel before being detected. D
related to the object sensitivity of the safety light curtain.
Object sensitivity (resolution) is the smallest diameter
object, which is detected anywhere in the sensing field.
T + T + T + T is measured by a stop time measuring
Note:
s c r spm
device.
Example (for US):
In a perpendicular safety-light curtain application with object
sensitivity (effective resolution) less than 64 mm (2.5 in.), the D
be approximated based on the following formula:
D (inches) = 3.4 × (Object Sensitivity – 0.276),
pf
But not less than 0.
For GuardShield Type 2:
Object sensitivity = 30 mm (1.18 in.)
Dpf = 3.4 x (1.18 - 0.276 in.) = 3.08 in.
Ts = 241 ms = 0.241 s
Tc = 10 ms = 0.01 s
Tr = 20 ms = 0.02 s
Tspm = 20% of Ts (calculated by the machine manufacturer) = 49 ms
= 0.049 s
K = 63in./s (determined by the machine manufacturer)
Ds = 63 x (0.241 + 0.01 + 0.02 + 0.049) + 3.08 in.
= 63 x 0.32 + 3.08 in.
= 20.16 + 3.08 in.
= 23.24 in. (600 mm)

European Safety Distance Formula

A safety distance must be maintained between the light curtain and the
point of danger. This safety distance helps ensure that the point of
danger can only be reached after the dangerous state of the machine has
been completely removed.
The safety distance as defined in EN ISO 13855 and EN ISO 13857
depends on:
• Stopping/run-down time of the machine. (The stopping/run-down
time is shown in the machine documentation or must be
determined by taking a measurement.)
• Response time of the protective device, for example, GuardShield™
Type 2 (for "Response Time" see page 4).
• Response time of the safety circuit:
• Reach or approach speed.
• Resolution of the light curtain.
6
is
pf
can
pf
Safety distance from the point of danger
How to Calculate the Safety Distance S
According to EN ISO 13855 and EN ISO 13857:
→ First, calculate S using the following formula:
→ If the result S is  500 mm (19.6 in.), then use the determined
→ If the result S is > 500 mm (19.6 in.), then recalculate S as
→ If the new value S is > 500 mm (19.6 in.), then use the newly
→ If the new value S is  500 mm (19.6 in.), then use 500 mm
Example (for Europe):
Stopping/run-down time of the machine = 290 ms
Response time safety circuit = 10 ms
Response time light curtain = 20 ms
Resolution of the light curtain = 30 mm (1.18 in.)
T = 290 ms + 30 ms = 320 ms = 0.32 s
S = 2000 × 0.32 + 8 × (30 – 14) = 768 mm (30.24 in.)
S > 500 mm (19.7 in.), therefore:
S = 1600 × 0.32 + 8 × (30 – 14) = 640 mm (25.1 in.)
Minimum Distance from Reflecting Surfaces
The infrared light from the sender is reflected off shiny surfaces and
received by the system receiver. If this condition occurs, it can result in
an object not being detected when it enters the GuardShield™ Type 2
sensing field.
All reflecting surfaces and objects (for example, material bins) must
therefore be at the minimum distance a from the protective field of the
system. The minimum distance a depends on the distance D between
sender and receiver.
Rockwell Automation Publication 440L-IN011B-EN-P - October 2017
Safety distance S (D )
s
Protective field height
Distance to avoid standing behind
the safety curtain 75mm
S = 2000 × T + 8 × (d – 14) [mm]
Where ...
T = Stopping/run-down time of the machine
+ response time of the protective device [s]
d = Resolution of the light curtain [mm]
S = Safety distance [mm]
The reach/approach speed is already included in the formula.
value as the safety distance.
follows:
S = 1600 × T + 8 × (d – 14) [mm]
determined value as the minimum safety distance.
(19.6 in.) as the safety distance.
Point
of
danger