2TLC172178M0201, rev. D
13
www.abb.com/lowvoltage
2011-11-15
Calculation of minimum distance (worst case):
x = L × tan (2 )
where
x
= minimum distance between two pairs
L
= distance between transmitter and receiver
= maximum spreading angle of light disturbance
NB: Example values are given in
Table 2
.
Reflecting surfaces
The Spot units must be set up in such a way that a reflecting surface may
never
be allowed to redirect the light
from the transmitter into the receiver. The minimum distance to a reflective surface (horizontal or vertical) from
which the Spot pair may be mounted is calculated depending on the distance between the transmitter and receiver.
Table 3
L
x
3 m
131 mm
5 m
0.22 m
10 m
0.44 m
20 m
0.87 m
35 m
1.53 m
Calculation of minimum distance:
If the distance (L) between the transmitter and receiver is less than or equal to 3 meters (L 3 m) the minimum
distance (
x
) is 131 mm.
If the distance (L) between transmitter and receiver is greater than 3 meters (L > 3 m) then the following formula
applies:
x = L × tan ( )
where
x
= minimum distance between Spot and reflective surface
L
= distance between transmitter and receiver
= maximum spreading angle of light disturbance
NB: Example values are given in
Table 3
.
x
L
= 2.5
Spot T
Spot R
Reflective surface
