Wintriss Shadow 8, User Manual

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Shadow 8 User Manual 1139300
Installation and Checkout 2-7
This formula is similar to the OSHA formula except that it incorporates additional variables
(i.e., response times, brake monitor setting, and depth penetration factor).
The hand-speed constant indicates how far you could theoretically move your hand and arm in
one second.
Ts, Tc, and Tr are the worst-case response times of the press (or other machine)
,
of the
control, and of the light curtain. The response time of the press Ts is measured at
approximately 90° of crankshaft rotation, or at maximum closing velocity. The response time
of the control Tc is the time it takes for the control to activate the press’s brake. The response
time Tr for Shadow 8 is between 23 mS (for protected lengths up to 42 in.) and 59 mS (for
lengths between 171 in. and 202 in.
Tbm is additional time added to the other response times in the ANSI formula to reflect brake
wear. It is calculated as follows:
Tbm = brake monitor setting – (Tc + Ts)
The brake monitor setting is a preset value that, when exceeded, causes the press control (or
other control) to automatically stop the press. When the preset value is reached, it indicates
that excessive brake wear has occurred, and it is time for repair of the brake.
See instructions for your brake monitor to determine the proper brake monitor setting.
Generally, the setting is 120% of the measured stopping time (Tc + Ts) when your brakes are
new. It is 110% of the stopping time (Ts + Tc) for older brakes.
The depth penetration factor Dpf equals 3.07 in. (78.0 mm). This is a measure of how far an
object, like an operator’s hand, can move through the light curtain before the light curtain
reacts. Dpf is related to the object sensitivity.
Object sensitivity is the smallest diameter object that Shadow 8 can detect anywhere in its
field. Object sensitivity (S) for Shadow 8 is 1.18 in. (30 mm) with beam centers of 0.79 in.
(20 mm). An object smaller than 1.18 in. diameter could pass through the light field if it
traveled in a path directly between the light beams.
For instructions on calculating the safety distance with one beam blanked, refer to Increasing
Safety Distance To Compensate for Blanking Windows, page 2-10.
An example of calculating the safety distance using the ANSI formula
The ANSI formula for calculating safety distance is
Ds = K x (Ts + Tc + Tr + Tbm) + Dpf
Let’s use the following numbers for our variables in the formula:
K = 63 inches per second
Ts + Tc = 0.190 sec.
We include Ts and Tc together because many stop time measuring devices measure the
stopping time of the press control as well as the stopping time of the clutch/brake mechanism.
Tr = .059 sec.
Tbm = 0.228 sec. – 0.190 sec = .038 sec.