ETAS
Hardware Description
ES650.1 - User Guide
19
3.6
Maximum Input and Common-Mode Voltages
The maximum input voltage between two inputs and the maximum voltage
between an input and case ground is 60 V DC / 30 V AC.
For an explanation of the maximum input and common-mode voltages, see the
illustration and example below.
Fig. 3
-
5
Maximum input and common-mode voltages
All capacitors between the inputs (U
in+
and U
in-
) and case ground have the
same capacity. The maximum voltage between any input and case ground is
60 V DC / 30 V AC.
Example
For the given input voltages U
inx
, U
iny
, U
inz
and the common-mode voltage
U
CMxy
, the maximum allowed common-mode voltage U
CMyz
is to be calculated.
U
inx
= 10 V
U
iny
= 5 V
U
inz
= 10 V
U
CMxy
= 15 V
max(U
inx
+ U
iny
+ U
inz
+ U
CMxy
+ U
CMyz
) = 2 U
c
= 60 V
10 V + 5 V + 10 V + 15 V + max(U
CMyz
) = 60 V
max(U
CMyz
) = 60 V - 40 V = 20 V
+
-
+
-
+
-
channel x
channel y
channel z
galvanically isolated
galvanically isolated
case potential
C
C
C
C
C
C
U
in+
U
in+
U
in+
U
in-
U
in-
U
in-
U
inx
U
iny
U
inz
r
`jñó
r
`jóò
r
Å
r
Å
