Fema M Series, User Manual, Page: 5 / 36

FEMA ELECTRÓNICA . SERIES M . M60-LC
5
1.8 Signal and power connections
Vexc+
Signal-
Sense-
Vexc-
1 2 3 4 5 6 7
Sense+
EK
7
EK ‘on / off’ rear control
(short circuit to ‘Vexc-’)
6
Vexc+ Excitation v
5
Sense+ Excitation voltage sense +
4
3
Signal- Signal -
2 Sense- Excitation voltage sense -
1
Vexc- Excitation voltage -
Figure 2 - Signal connections
1.8.1 Connecting the ‘sense’
Measuring with load cells requires a stable and accurate ex -
citation voltage. Connecting the ‘
sense +
’ and ‘
sense -
’ termi -
nals to the load cell, provides the instrument with an accurate
value of the excitation voltage received by the cell. Deviations
and errors from the standard excitation value are automati -
cally compensated by the instrument, increasing the accuracy
and reliability of the measure.
If you do not wish to use the ‘
sense
’, place a shortcircuit be -
tween terminals ‘
sense +
’ and ‘
Vexc+
’, and between terminals
‘
sense -
’ and ‘
Vexc-
’.
For applications with multiple cells (2, 3, 4 cells or more) con -
nect the ‘ sense ’ wires to the ‘electrical middle point’ of the
power wires of all the cells
(see section 1.16.4)
.
1.8.2 Connecting the cell to the ground
Measuring with load cells requires an electrically clean instal -
lation. When connecting the ground to the cell system, assure
that :
• the cell connection to ground is performed in such a way
that the current to ground DOES NOT flow through the cell.
8 9 0
8 Neutral AC / Negative DC
9 Not connected
0 Phase AC / Positive DC
Figure 3 - Power connections
1 2 3 4 5 6 7
Vexc+
Signal-
Sense-
Vexc-
Sense+
EK
Figure 4 - Example for connections with 1 load cell.
!
The ‘sense’ terminals must be always connected.
If you do not use the ‘sense’, shortcircuit with
‘Vexc’ terminals
(see section 1.8.1) .
!
Fuse : to comply with the security regulation 61010-
1, add to the power line a protection fuse acting as
a disconnection element, easily accessible to the op-
erator and identified as a protection device.
• Power ‘H’ 250 mA time-lag fuse
• Power ‘L’ 400 mA time-lag fuse
1.8.3 Real cases
See section
1.16
for different examples on how to con -
nect the load cell and configure the instrument.