MAN3041-1
19
Galvanically isolated barriers are available as single or dual channel versions and are recommended for any
application in which direct earth connections are not acceptable. Table 3 shows details of available barriers.
The galvanically isolated barrier is a two-wire device which does not need an external power supply.
10.2
Approved safety barriers
The system certification includes a generic specification for barriers.
The generic specification is:
any shunt zener diode safety barrier certified by BASEEFA or any EEC approved certification body to
[Ex ia] IIC
having the following or lower output parameters:
Uz = 28V
I max:out = 93.3mA
W max:out = 0.67W
In any safety barrier used the output current
must be
limited
by a resistor ‘R’ such that
I max:out = Uz
R
A number of shunt zener diode barriers meet this specification and examples are given below:
Manufacturer
Type
Polarity
Mounting
Pepperl & Fuchs
Z 728
+ve
DIN
–
rail
Pepperl & Fuchs
Z 828
-ve
DIN
–
rail
Pepperl & Fuchs
Z 428/Ex
+ve
DIN
–
rail/surface
Pepperl & Fuchs
Z 528/Ex
-ve
DIN
–
rail/surface
MTL
+ve
Busbar
MTL
+ve
DIN
–
rail
MTL
+ve
DIN
–
rail
Table 2
–
28V300
Ω
single channel safety barriers
Suitable transformer isolated current repeaters (galvanic barriers) are shown in Table 3.
Manufacturer
Type see table on
AZ20984
No of Channels
Certificate
Pepperl & Fuchs
KFDO CS EX 1.51P
1
BAS00ATEX 7087
MTL
MTL 4061
2
Ex94C2040X
MTL
MTL 5061
2
Ex94C2040X
Table 3
–
Transformer Isolated (galvanic) barriers
