Campbell NW8002, Instruction Manual

Page: 15 / 39

SECTION 1. WEATHER STATION DESCRIPTION AND INSTALLATION
1-10
The two leads from the charging source can be
inserted into either of the CHG ports, polarity
doesn't matter. A transzorb provides transient
protection to the charging circuit. A sustained
input voltage in excess of 40V will cause the
transzorb to limit voltage.
CAUTION: Switch the power to "off" before
disconnecting or connecting the power
leads to the Wiring Panel. The Wiring
Panel and PS12-LA are at power ground. If
12V is shorted to either of these, excessive
current will be drawn until the thermal fuse
opens.
Do not use the external port, labeled EXT, with
the PS12-LA.
TABLE 1.5-1. PS12-LA Battery and AC
Transformer Specifications
Lead Acid Battery
Battery Type
Yuasa NA 7-12
Float Life @ 25
o
C 5 years typical
Capacity 7.0 amp-hour
Shelf Life, full charge Check twice yearly
Charge Time (AC Source) 40 hr full charge,
20 hr 95% charge
AC Transformer
Input:
120V AC, 50/60 Hz
Isolated Output: 16 VAC @ 350 mA
max.
There are inherent hazards associated with the
use of sealed lead acid batteries. Under normal
operation, lead acid batteries generate a small
amount of hydrogen gas. This gaseous by-
product is generally insignificant because the
hydrogen dissipates naturally before building-up
to an explosive level (4%) occurs. However, if
the batteries are shorted, or overcharging takes
place, hydrogen gas may be generated at a rate
sufficient to create a hazard. Campbell
Scientific makes the following
recommendations:
1. A CR10 equipped with standard lead acid
batteries should NEVER be used in
applications requiring INTRINSICALLY
SAFE equipment.
2. A lead acid battery should not be housed in
a gas-tight enclosure.
1.5.2 SOLAR PANEL
The solar panel is mounted above the
datalogger enclosure facing south (Figure 1.6-
1). The lead wire is routed through the
enclosure base and connected into the two
terminals on the PS12-LA labeled CHG.
Polarity does not matter (Figure 1.5-1). When
the solar panel is connected in, the red LED
light should light, indicating that the batteries are
being charged.
1.6 SENSOR WIRING
Figure 1.3-2 shows how sensor lead wires are
routed through the crossarm and cover. Route
sensor wires through the center hole of the
crossarm, down the mast, and into the base of
the enclosure.
NOTE: The solar radiation sensor has a
large end on the cable. Wire it into the
enclosure first.
Connect sensor wires to the CR10WP wiring
panel as shown in Figure 1.6-2.
Once all wiring is completed, use electricians
putty to seal the cable entry hole.
1.7 STATION GROUNDING
Proper grounding of the station minimizes
damage from electrical transients.
A ground lug is provided at the base of the
enclosure (Figure 1.3-1). Everything inside the
enclosure is grounded to the ground lug. A 14
awg or larger ground wire should be run from
the enclosure ground lug to earth ground. The
weather station mast should also be connected
to earth ground (Figure 1.7-1).