Electrical connection
14
A05569_01_X00_00
HBM: public
AD105D
Important
The AD105D is an unshielded motherboard and is thus not EMC-tested. Either
install the electronics in a closed (electrically conductive) transducer housing or
in a separate EMC-tested housing.
Connect the transducer, AD105D housing, and cable shields to a joint ground
to realize effective shielding against electromagnetic interferences. The elec
tronics is protected against interferences with filters on the interfaces and exci
tation voltage.
5.1
Transducer connection
A 4-wire shielded cable is sufficient for connecting the transducer. If the trans
ducer has a 6-wire cable, the bridge excitation voltage and sense lead must be
connected as illustrated in
. The connection should be as short as pos
sible. Depending on the bridge resistance of the transducer being used and the
length and cross-section of the transducer cable, there may be voltage drops
that can reduce the bridge excitation voltage. The voltage drop on the connec
tion cable is also dependent on the temperature (copper changes its resistance
with the temperature). The output signal of the transducer changes proportion
ally with the changing bridge excitation voltage. The 4-wire circuit used here
will result in measurement errors if temperatures fluctuate. This is caused by
the temperature-dependent cable resistance.
When establishing a measurement chain where the electronics are positioned
outside the transducer, ensure that the AD105D uses a rectangular carrier fre
quency for the bridge excitation. The cable length between AD105D and the
transducer should therefore be limited to max. 100 cm. A max. length of 30 cm
should not be exceeded for precision applications (≥ 3000 d).