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CAUTION:
Grounding the CSAT3BH is critical. Proper grounding to earth will ensure maximum
electrostatic discharge (ESD) and lightning protection and improve measurement accuracy.
The data logger, CSAT3H heater controller box, and CSAT3BH electronics should all be
grounded to the same grounding rod.
On the back of the CSAT3BH block is a copper grounding lug (refer to
(p. 41)). Use a
standard flat-head screwdriver to pinch a wire (from 8 to 14 AWG) between the lug and the lug
screw. Campbell Scientific offers a 10 AWG copper wire that is suitable for grounding sensors.
Connect the other end of the wire to the tripod or tower, which should be grounded to earth with
a grounding rod. A 5-ft copper-clad grounding rod ships with Campbell Scientific tripods, or it
can be purchased separately.
The CSAT3BH has three watertight circular ports or connectors at the rear of the block. These are
labeled Power/SDM, USB, and CPI/RS-485 as shown in
(p. 41). Unless a port is in use
and connected to a cable, they should be securely covered by one of the caps that are captive to
the CSAT3BH.
1. Ground the CSAT3BH, data logger enclosure, and the CSAT3H controller box to the tower
by attaching a user-supplied, heavy-gauge wire from the copper grounding lug on the
back of the CSAT3BH block and the CSAT3H controller box (see
(p. 41) and
(p. 41)).
2. Earth (chassis) ground the other ends of the wires to the CSAT3BH mounting structure or to
a grounding rod. Proper grounding lends stability and protection to a data acquisition
system. It is the easiest and least expensive insurance against data loss—and often the
most neglected. The following terminals are provided for CSAT3BH and CSAT3H controller
box grounding.
a.
⏚
Signal ground reference for single-ended analog inputs, pulse inputs, excitation
returns, and as a ground for sensor shield wires. Signal returns for pulse inputs should
use
⏚
terminals located next to the pulse input terminal. Current loop sensors,
however, should be grounded to power ground.
b. G Power ground return for 5V, SW12, and 12V terminals; current loop sensors; and C
configured for control. Use of G grounds for these outputs minimizes potentially
large current flow through the analog-voltage-measurement section of the wiring
panel, which can cause single-ended voltage measurement errors.
c.
⏚
Earth ground lug connection point for a heavy gauge, earth ground wire. A good
earth connection is necessary to secure the ground potential and shunt transients
away from electronics. A minimum 14 AWG wire is recommended.
CSAT3BH Three-Dimensional Heated Sonic Anemometer
40