NMG2
®
Stop-Time Measuring System
Version 3.0.0
www.asm-sensor.com
23
4.6 Calculation of the Safety Distance
Safety Distance
The minimum safety distance for 2-hand guards or safety light curtains is calculated as a product of the
machine stop-time and a determined maximum hand speed. The actual valid safety regulations (EN ISO
13855, EN999 etc.) have to be regarded. The stop-time measurement must be made at the worst conditions
of the machine to determine the maximum stop-time and the correct safety distance.
Calculation of the Safety Distance
(presentable via printer or RS-232)
In the automatic measurement mode (
MULTIPLE
[8] pushed) the safety distance of the safety equipment (2-
hand control, light curtain etc.) can be calculated. If the hand speed is not zero in the basic setting, the safety
margin is calculated from the max. stop time. A number of measurements can be set.
The following formula is used:
s = gr · (t1 · F1 + t2) + F2
with
s
= Safety distance in mm
gr
= approach speed (adjustable in steps of 100 mm/s).
t1
= Measured stop time
F1
= Proportional addition factor for stop time (adjustable from 100 up to 200 %).
Designated as [F1] in the basic setting
F2
= Addition to the safety distance (adjustable in steps of 10 mm)
t2
= Addition to the stop time (adjustable in steps of 10 ms)
Corresponds to the reaction time of the safety equipment.
Examples:
The up-to-date valid standards and minimum safety distances must always be observed.
1. 2-hand control with cover (see EN ISO 13855)
gr = 1600 mm/s; F1 = 100 %; F2 = 0 mm; t2 = 0 ms
2.
Light curtain with a resolution ≤14 mm (see EN ISO 13855)
gr = 2000 mm/s; F1 = 100 %; F2 = 0 mm (depending on the sensor detection ability); t2 = 20 ms (resp. other
reaction time of the ESPE*).
* Electro Sensitive Protective Equipment
3. Interlocking device associated with guards (see EN ISO 13855)
gr = 1600 mm/s; F1 = 100 %; t2 = 0 ms; F2 = 0 mm (depending on the aperture)
Automatic Measurement with Safety Distance Calculation
Set the NMG2 in the automatic measurement mode (
SINGLESHOT/MULTIPLE
pressed, button
TEST
RUN/ADJUST
released). The printout shows the header with the assigned formula parameters. Start the
machine. The machine will be stopped and the stop contact will be released. Proceed to the assigned
number n of measurements, then terminate the automatic measurement by setting the
button TEST RUN/
ADJUST
to the
ADJUST
position. Minimum and maximum stop time will be determined and printed. The
safety distance will be calculated by the max. stop time and the given formula parameters and then be
printed.
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