IDEC SG4 Type 4 Finger & Hand - Manual (Page 10)

SG4-B Series Instruction Manual
6
1.3.3. Minimum installation distance
The safety device must be positioned at a specific safety distance
(Fig. 3). This distance must ensure that the dangerous area cannot
be reached before the dangerous motion of the machine has been
stopped by the ESPE.
The safety distance depends on 4 factors, according to the EN-999
Standard:
 Response time of the ESPE (the time between the effective beam
interruption and the opening of the OSSD contacts).
 Machine stopping time (the time between the effective opening of
the contacts of the ESPE and the real stop of the dangerous motion
of the machine).
 ESPE resolution.
 Approaching speed of the object to be detected.
Fig. 3
The following formula is used for the calculation of the safety
distance:
S = K (t
1
+ t
2
) + C
where:
S = Minimum safety distance in mm.
K = Speed of the object, limb or body approaching the
dangerous area in mm/sec.
t
1
= Response time of the ESPE in seconds
(see section 10 “Technical data”)
t
2
= Machine stopping time in seconds.
d = Resolution of the system.
C = Additional distance based on the possibility to insert the body or one
of body parts inside the dangerous area before the protective
device trips.
C = 8 (d -14) for devices with resolution ≤ 40 mm.