502-3000 Series Ztron
TM
Point Level Control
Operation
22
3.3 Failsafe Selector
Failsafe describes the level condition which causes the output
relay to de-energize and the condition of the relay upon loss of
power or most component failures.
• The failsafe is field selectable by changing the position of
the connector located on the instrument circuit board. See
Figure 3-2.
• High Level Failsafe (HLFS) means the relay will de-
energize when level is high, indicating high level upon
loss of power. (
N
.
O
. contacts open/
N
.
C
. contacts closed)
• Low Level Failsafe (LLFS) means the relay will de-
energize when level is low, indicating low level upon loss
of power. (
N
.
O
. contacts open/
N
.
C
. contacts closed)
• The instrument is supplied in the failsafe mode that is
requested when the order is placed (HLFS, if not speci-
fied).
3.4 Start-up
Before applying power to the instrument, be sure that the
power wiring is correct. See Section 2.3.
Figure 3-2
Failsafe Selector
