DCA
Direct Current Alarm
SUPPLEMENT
August 1992
To Manual No. 192-701-00 G
Purpose
This supplement is being distributed to users of
Moore Industries' Direct Current Alarm (DCA) to in-
form them of corrections/additions to the current
manual since its release date. These changes will
be incorporated in the manual during its next revi-
sion.
Corrections
The wording of the second paragraph of step 4 of the
"Setting Low-Alarm Trip Points" (page 14) and "Set-
ting High-Alarm Trip Points" (page 15) calibration
procedures should read:
In a low alarm, 100% input is a non-alarm condi-
tion. If connected to XNO and COM terminals (X =
U or L (upper or lower); NO = normally open). Resis-
tance across these terminals in a fail-safe alarm is
near zero. In a non-fail-safe alarm, resistance will be
infinite.
It is important to understand that the "normal" con-
dition of these relays refers to the
non-energized or
de-energized state of the relay. This means that the
terminal labeling is true when power is removed from
the unit or when the unit is operating and the LED is
NOT lit. Since each LED illuminates only while the
corresponding relay is
energized, when the LED is
not lit its corresponding relay is de-energized.
So, regardless if the DCA is configured for fail-safe
or non-fail-safe operation, each relay's normally-open
or normally-closed contact states are true as labeled
only when the relay is de-energized.
Addition
The hookup connections for units configured with the
TX Opton are not provided in the Installation Section
of the user's manual. For units with the TX Option,
connect the positive output lead from the external
equipment to the +TX terminal on the DCA, and con-
nect the minus output lead from the external equip-
ment to the +IN terminal of the DCA. Do not use the
-IN when installing DCA's with the TX Option.
