Endress+Hauser nivector FTC 968 Montage- Und Betriebsanleitung Seite 13

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Fail-safe Mode
The Nivector can be used as a fail-safe device for either
upper or lower limit switching. Fail-safe means that it
switches to a no-current mode when the limit (» » f f u u l l l l « « or
»em m p p t t y y « « ) is reached. This »alarm« then has the same »e
switching status as when a power failure occurs
(quiescent current safety principle).
The Nivector must be set to the maximum fail safe mode
when used as an upper limit switch and be set to the
minimum fail-safe mode when used as a lower limit switch
- or the other way round.
The M M I I N N - - M M A A X X switch in the connection area of the
Nivector is set with a screwdriver (see Fig. 2, Page 2).
Maximum fail-safe means that the electronic switch blocks
if the bulk solid covers the tip of the Nivector:
Minimum fail-safe means that the electronic switch blocks
if the bulk solid is not covering the tip of the Nivector:
• Switch on power supply
For this adjustment
the Nivector must
not be connected to
a voltage supply
M M a a x x i i m m u u m m
F F a a i i l l - - S S a a f f e e M M o o d d e e
Fig. 8
Maximum fail-safe
mode
M M i i n n i i m m u u m m
F F a a i i l l - - S S a a f f e e M M o o d d e e
Fig. 9
Minimum fail-safe
mode
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