Connections Between Several Transmitters And A Control Unit With Hart Multidrop Connections - Dräger Polytron 7000 Instructions For Use Manual

Electrical connections
Connections between several transmitters and a control
unit with HART multidrop connections
Each transmitter must first be put into service separately. Use the menu

item "Polling Address" to assign a different polling address in the range "1"
to "15" to each transmitter which is to be connected to the multidrop cable
(see page 70). It is best to assign sequential polling addresses, starting with
"1".
Installing the transmitters in areas subject to explosion hazards of zone
0 or zone 1
Depending on the supply unit, up to 7 transmitters can be connected to a 2-

wire or 3-wire cable.
The second cable gland is used for the cable to the next transmitter.
Install a safety barrier with the appropriate explosion protection approval

(category 1, 2 or Div. 1) between the transmitter and the control unit.
— Only safety barriers with the following characteristics may be used: U
≤30 V, I ) ≤0.3 A, P
(I
o sc
— Take care that the maximum permissible capacitance and inductance of
connections to the safety barrier 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
— The safety barrier must be capable of transmitting the communications sig-
nals in both directions between the explosion-hazard area and the non-ex-
plosion-hazard area. Several manufacturers offer special SMART
transmitter supply units for this purpose.
SMART transmitter supply units
(with HART-communication between Ex/Non-Ex area)
The following safety barriers are provided as examples only and have not
been certified for use in combination with the P3U. Selected barriers must be
acceptable to the authority having jurisdiction and comply with the assigned
P3U entity parameters also taking the cable into account.
Manufacturer Type
RN 221 N–B1
(ATEX)
Endress +
RN 221 N–C1 (FM)
Hauser
RN 221 N–D1 (CSA)
RN 221 N–E1 (TIIS)
MTL MTL 5042
Pepperl & Fuchs KFD2–STC4–Ex1
— If a HART hand-held terminal is used, the permissible values may be lower.
Observe the safety-related parameters of the hand-held terminal.
18
≤700 mW.
o
suitable for
Zone 0
Div. 1
Zone 0, Div.
1
Zone 0, Div.
1
(V )
o oc
i
R
Cable
for up to for up to
5 transmitters 6 transmitters
≤ Ω ≤
120
≤ Ω ≤
33
≤ Ω ≤
90
(Total)
for up to
7 transmitters
Ω
50 – – –
Ω ≤ Ω
27 20
Ω
10 – – –