Honeywell SmartPAC 2 User Manual page 372

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T bm is additional time added to the stop time of the press to allow for brake wear. You must
allow extra time for brake wear because any safety distance based only on stop time will
become too short as the brake wears. T bm is calculated when you set the brake monitor for
SmartPAC 2. You must calculate and set the stop time limit before calculating safety
distance for the light curtain. You are told how to calculate T bm when setting the stop time
limit.
D pf is the depth penetration factor. 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. D pf is related to the
object sensitivity of Shadow. Object sensitivity is the smallest diameter object Shadow will
detect anywhere in its field.
Object sensitivity (S) for Shadow V is 1.25" (3.2 cm). Based on S and ANSI B11.1–1988,
D pf = 3.3" (8.4 cm)
For Shadow V with one beam blanked, S = 2" (5.1 cm) and D pf = 5.9" (15 cm). This means
D pf increases by 2.6" (6.6 cm) when you add one blanking window.
An example for calculating the safety distance using the ANSI formula
Below is an example of how to use the formula to calculate safety distance (D s ). First take
another look at the formula we must use:
D s = K x (T s + T c + T r + T bm ) + D pf
Let's use these numbers for our variables in the formula, and assume that the 90° Stop-time
Test indicated 190 milliseconds:
K (hand speed constant) = 63 inches per second (set by OSHA)
T s + T c = 0.190 sec.
T r = .030 sec. (response time of Shadow)
Let's take T bm from example 2 from the Stop Time Limit calculations performed earlier in
this chapter.
T bm = 0.210 sec. (brake monitor setting) – 0.175 sec = .035 sec.
D pf = 3.3
Now let's put our numbers into the formula:
D s = K x (T s + T c + T r + T bm ) + D pf
D s = 63 x (0.190 + .030 + .035) + 3.3
D s = (63 x .255) + 3.3
D s = 16.1 + 3.3
D s = 19.4"
The distance the light curtain must be mounted from the pinch point in our example is 19.9."
When using the formula, be sure to do all calculations in this order:
(1) Add T s + T c + T r + T bm first.
(2) Multiply the result by 63.
(3) Add this result to D pf . This is D s .
If you do not follow this order, your safety distance calculation will be incorrect.
Page 350
SmartPAC 2 with WPC Integration
Chapter 6 SmartPAC 2 Run Mode