HBM U2B, Mounting Instructions, Page: 15 / 60

15
U 2B
H BM A03823.3en/de/fr
5.2 Sixwire c onn ecti on
The g rey and g ree n w ires that are pro v ided in addition to the con v entional
four w ire connection pick off the actual v alue of the bridge e x citation v oltage
on the transducer and feeds it back to the appropriate measurement electron
ics. This then corrects the e
x citation v oltage so that the set v alue is a v ailable
to the transducer lossfree. Possible changes in the resistance of the cable
due to temperature or a cable e
x tension are therefore constantl y corrected,
e v en during a measurement. It is therefore possible to e x tend the cable
w ithout an y problem.
w h ( w hite)
bk (black)
rd (red)
bu (blue)
gn (green)
g y (gre y )
y e ( y ello w )
Measuring signal (+) U
A
Bridge e x citation v oltage (+) U
B
Sensor circuit (−)
Sensor circuit (+)
Bridge e x citation v oltage (−) U
B
Measuring signal (−) U
A
C able shielding, connected to housing
Fi g .5.1: U 2B pin assignment
Eart h i ng sc h eme (Gree n Li n e)
The cable shielding is connected in accordance w ith the Greenline scheme.
U nder this scheme, the measuring s y stem is enclosed in a Farada y cage.
Inside this cage, electromagnetic interference has no effect on the measuring
signal. The transformer section is protected from electromagnetic influences
b
y special electronic coding procedures.
When there is interference due to potential differences (balance current), the
connections bet
w een zero operating v oltage and the bod y of the casing must
be separated on the amplifier and a potential equalisation line must be fitted
bet
w een the housing and the amplifier housing (highl y fle x ible stranded w ire,
10 mm
2
line crosssection).