Type / N°
Rev.
Fw
Date
Page
Total pages
EW055.600D
D
4L
6
th
June 2018
11
43
EsiWelma
®
s.r.l.
The computing head can work in Self Service mode following the procedures required and
described below:
2.5.1
Electrical devices involved
In addition to the lights (red and green) the
following devices will be installed on board of the
dispenser: a “deadman’s break” push button
(mushroom head, no block, normally open) , an
emergency push button (with block interrupting the
power supply to distributor) and a 3-position key
selector (1 unstable and 2 stable).
Figure 8:
“deadman’s break” push button
Aloof (safe zone), a button (normally closed) to disable the delivery to the user by the
operator (connected in series with the dead man's button).
The computing head manages these devices by the following digital inputs.
1
Input «
deadman’s break » temporary voltage free contact, normally open
2
Input «Reset
deadman’s break » temporary contact of the 3-position key selector
3
Input selector «Self (AUT) / Served (MAN)» bistable contact of the 3-position key
selector, contact closed in position Served.
2.5.2
Sequence of delivery
The 3-position key selector allows the operator to choose the operating mode of the
dispenser: Manual (SERVED) or Automatic (SELF-SERVICE).
The positions of the selector are:
1
Deadman’s break
Reset
(counterclockwise
rotation) temporary, return to central position
2 Automatic
Self-Service (central position)
close stable contact.
3 Manual
Served (clockwise rotation),
open stable contact.
The key can be removed only in positions 2 and 3
Figure 9:
Activation Key of
Self-Service/Served mode
Manual (Served) mode works as described in §2.2.
In addition to what already explained, operator can stop and restart the flow of gas without
resetting the current delivery. By the
“deadman’s break” push button in the manual mode, the
delivery starts and stops alternately every time it is pushed.
This function can be repeated several times consecutively without resetting the counting. The
delivery definitely finishes when the user puts the nozze back in place or when the condition
of low flow (full bottle) is reached.
Comune
Deadman's break (NO)
2
3
Common
Temporary N.O.
N.O.
1
Aut
Reset
