Honeywell Enraf 854 ATG, Руководство по установке, Страница: 16 / 24

Electrical installation
Page 16 Installation guide 854 ATG
Intrinsically safe options
The cables for the intrinsically safe options shall only be fed through the cable entries at the side of
the intrinsically safe (blue) terminals. Blue marked cables are recommended for the intrinsically
safe options.
Caution
The intrinsically safe options described in this section are explosion-proof certified.
Make sure that the certificate of approval is available on site and act in accordance
with the instructions as given in the approval certificate.
Caution
Intrinsically safe wiring shall be separated from all other wiring.
Cable lay-outs shall be in accordance with local regulations.
Note:
The shield of the intrinsically safe cable shall not be connected inside the 854 ATG housing.
Connect the shield of the cable externally in the cable gland at both ends of the cable.
Device Cable requirements
Spot temperature element :
Shielded; R
max
= 12 Ω / line.
Average temp. element :
Twisted pair and shielded; R
max
= 25 Ω / line.
(combined water probe) Wiring between the 854 ATG and 762 VITO must be protected with
EMC shielded conduit. Same conditions for connection to 862 MIR.
Pressure transmitters :
Twisted pair and shielded; R
max
= 25 Ω / line (only pressure
transmitters with HART
7
protocol).
Pressure transmitter P1 is the bottom transmitter (measures liquid
head) and P3 is the top transmitter (measures vapour pressure).
Note:
If pressure transmitters are connected to HART input 2, it must be verified that the maximum
values for current and power of the HCU option board HART input 2 circuit are not exceeding the
maximum values of the connected pressure transmitters. Refer to Appendix C.
If the values of the HART input 2 circuit are too high, then connect the pressure transmitters to
HART input 1 and the 762 VITO Interface to HART input 2 (only possible when HART input 1 is
available!).