Dräger Polytron 7000 Instructions For Use Manual page 13

— The cable resistances given apply for a load resistance of 250
load resistances can drastically reduce the permissible cable resistance!
When other barriers have been selected, care must be taken that the volt-

ages on the transmitter do not fall below the following values when barrier
parameters and cable resistance are taken into account:
16.5 V for a current of 3 mA and 8.0 V for a current of 22 mA.
If HART communication is to be used, the HART specifications must also

be observed.
The maximum possible cable lengths can be found in the table on page 19.

In each case, use the line marked "Number of transmitters = 1".
— Connect shielding to earth point and/or 0 V (Ex i).
Explosion-hazard area, zone 0, 1 or Div. 1
4 to 20 mA
+24 V
Installing the transmitters in explosion-hazard areas of zone 2
— Use only supply units or a safety barrier of the device category 3.
— Only supply units or safety barriers with the following characteristics may
be used: U (V ) ≤ 30 V, I
O OC
— Take care that the maximum permissible capacitance and inductance of
connections to the supply unit are not exceeded, also taking the cable into
account.
The safety-related input parameters of the transmitter are:
C = 5 nF, L = 50 µH.
i i
The category 1 marking has to be cut out from the rating-plate label. Once
the unit has been used after installation in the above manner, it may never
be installed in explosion-hazard areas of zone 0 or zone 1 (device category 1
or 2). Explosion hazard!
The maximum possible cable lengths can be found in the table on page 21.

In this table, select the line, " Number of transmitters = 1".
(I ) ≤ 0.3 A, P ≤ 700 mW.
O SC O
CAUTION
Ω
. Higher
Non-explosion-hazard area
Safety barrier
Ex i
PA
Earth point
Electrical connections
+
4 ... 20 mA
+
–
0 V
Control unit
13