NEX7250 Zone 2 Annunciator
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6. Inputs
6.1 Optically Coupled Inputs
All alarm inputs are provided with fully isolated inputs using optical couplers and a transient filter is
built into the input circuitry so that low voltage interference will be ignored.
6.2 Standard Input Configuration
The standard Series 725 annunciator can be set to operate from volt free signal contacts that are
either normally open or normally closed.
Setting function F1 to the off state conditions the input to accept a normally open contact.
Setting function F1 to the on state conditions the input to accept a normally closed contact.
6.3 Signal Supply Voltage
On standard units an internally fused 24vdc signal supply (+VC), derived from the 24VDC logic
supply (+V), is distributed to all of the common terminals marked “C” which are located to the right of
each signal input terminal as typically shown below.
Typical Signal Supply Voltage Distribution
Logic supply
Internally distributed
signal supply voltage
Internal
1A signal
supply fuse
OVC
OV
+V +VC
R
T
A
ST
M FR
SPR
MULT
SUPPLY 24VDC
HNA HNB
GPB
GPA
C
1
C
2
+24V
OV
