2TLC172188M0201, rev. H
37
www.abb.com/lowvoltage
2012-01-03
Formula for calculating the minimum safety distance
The calculation of the minimum safety distance is performed in accordance with the standard EN 999:1998 where
the general formula for the minimum distance from the danger zone is:
S = K x T + C
where
S
is the minimum distance in millimetres, from the danger zone to the detection point, line, plane or zone;
K
is a parameter in millimetres per second, derived from data on approach speeds of the body or parts of the
body;
T
is the overall system stopping performance in seconds;
C
is an additional distance in millimetres, based on intrusion towards the danger zone prior to actuation of the
protective equipment.
The overall system stopping performance T comprises a minimum of two phases:
T = t
1
+ t
2
where
T
is the overall system stopping performance;
t
1
is the maximum time between the actuation of the sensing function and the output signal switching devices
being in the off state;
t
2
is the maximum response time of the machine, i.e. the time required to stop the machine or remove the
risks after receiving the output signal from the protective equipment. t
2
is influenced by various factors e.g.
temperature, switching time of valves, ageing of components.
4.11 Compare measurements
To compare measurements they are drawn as different layers in the graph form. The current measurement is
shown in colour and the layers beneath are shown in grey. Click on “Options” – “Layers” in the graph form, and a
new form will show, where you can choose to add or remove measurements from the layers.
In the list to the left all added layers are displayed. The layers are displayed with a number and the measurement
date. In front of the measurement is a checkbox which indicates if the layer should be displayed in the graph
window or not.
The button ”Add current” adds the current
measurement as a new layer. The button “Delete
last layer” removes the last layer from the list.
The button ”Delete all layers” removes all layers
from the list.
The button ”Clear layers” unchecks all layers in the
list so that they are not displayed in the graph
window.
With the button ”Apply” the current settings are
accepted and applied to the graph window. The
button “Exit” closes the form.
When a new layer is added to the list on top of
another layer, the zoom is automatically adjusted
after the existing layer so that the measurements
can be compared.
