12
RS85
VIBR ATING FORK LEVEL SWITCH | OI/RS85-EN REV. K
Fail safe/relay operation
A fail safe relay operation is used to energize the relay when
the switch is in normal condition. This will indicate that the
switch has power. Therefore in a fail safe high application, the
relays will be energized when the level is below the switch (dry
fork) and de–energized when the level is above the switch
(wet fork). Likewise, setting the switch Fail Safe to Low will
cause the relays to be energized when the level is above the
switch (wet fork) and de–energize when the level is below
switch (dry fork). The default setting for the fail safe or relay
operation of the resonator is high. To change the fail safe
operation for the relays, place the magnet in the S1 position
(Figure 24) or press pushbutton S1 (Figure 25) for 5 seconds.
LED1 will change back and forth from red to green. Removing
magnet on red will change fail safe to green (fail safe high).
Removing magnet on green will change fail safe to red (fail
safe low). Should power be lost, the relay will de–energize.
Figure 24
Figure 25
Table 2 – Fail safe/relay operation
Fail safe
Relay state (led)
Dry fork
Wet fork
Low level switch (fail safe
low)
Off (red
)
On (green)
High level switch (fail safe
high)
Default setting
On (green)
Off (red)
3 . . .Setup (configuring switch)