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62
Reference Manual
00809-0100-4140, Rev AA
January 2017
4.2
Cable selection
Wiring should be adequately rated and not be susceptible to mechanical damage.
Electrical conduit is commonly used to protect wiring. The wiring to this device must
maintain creepage(1) and clearance distances. Therefore, the conductors stripping length
should be no greater than 6 mm and be free from stray strands.
Use shielded twisted pairs to get the best results. To ensure proper communications, use
24 AWG, to a maximum of 14 AWG, and do not exceed 5000 ft. (1500 m). Cable length is
limited by the selection of monitoring resistance and wire gauge.
All power to the level detector is supplied over the signal wiring. Signal wiring does not need
to be shielded, but use twisted pairs for best results. Do not run unshielded signal wiring in
conduit or open trays with power wiring, or near heavy electrical equipment. For high
EMI/RFI environments, shielded twisted pair cable should be used.
4.3
Cable gland/conduit
For explosion-proof/flameproof installations, only use cable glands/conduit entry devices
certified as explosion-proof/flameproof. For ordinary location installations, use suitably
rated cable glands to maintain the IP rating.
Un-used conduit entries must be sealed with a suitably rated blanking plug.
See
for all other details.
4.4
Power supply
Terminals in the housing provide connections for signal wiring.
Rosemount 2140 and Rosemount 2140:SIS Level Detectors (“level detectors”) operate with
the following power supplies:
10.5 to 42.4 Vdc (10.5 to 30 Vdc in Intrinsically Safe installations).
For HART communication, a minimum loop resistance of 250
is required. Maximum loop
resistance is determined by the voltage level of the external power supply (
).
Figure 4-1. Load Limitation
Maximum Loop Resistance = 43.5 * (External Power Supply Voltage – 10.5)
Voltage (Vdc)
Lo
ad
(
s)
Operating
Region
1387
1000
500
0
10.5
20
30
42.4
Содержание Rosemount 2140
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Страница 14: ...4 Reference Manual 00809 0100 4140 Rev AA Introduction January 2017 Introduction ...
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