Celec LTR7000, Руководство пользователя и техническое руководство

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User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 19
TERMINALS #3 - #4 (mA OUTPUT SIGNAL)
Terminals #3 (I
OUT
) and # 4 (COM) provide the mA output signal during operation.
The output range (4-20mA / 0-20mA / 4-21mA) can be selected from the internal
configuration dip-switch.
When 4-
21 mA output range is selected, the V output doesn’t have a normal behavior.
Don’t use V output when this mA range is selected.
Notice that, even if the selected maximum output value is 20 or 21mA, this output may be
configured to provide
24mA for ERROR recognition (SW4 at the internal dip-switch).
Refer to the relevant section in this manual for more information.
For having the signal unaffected from any interference, it is recommended to use a shielded
cable with twisted pair, properly grounded at the side of the signal receiving device.
MAXIMUM LOAD RESISTANCE (R
L
)
The output current is proportional to level height. In order to get proper and linear mA
fluctuation, a maximum load resistance R
L
(including line resistance) must not be exceeded
depending on the supply voltage ( V
PS
) of the device. Consult the following table for the
maximum load resistance you should have for each supply voltage.
V
PS
(V)
max R
L
( Ω )
for 20mA max output
max R
L
( Ω )
for 24mA max output
15 550 420
16 600 460
17 650 500
18 700 540
19 750 580
20 800 620
21 850 660
22 900 700
23 950 740
24 1000 780
25 1050 820
26 1100 860
27 1150 900
28 1200 940
29 1250 980
30 1300 1000
31 1350 1040
32 1400 1080
33 1450 1120
34 1500 1160
35 1550 1200
36 1600 1240