Operating instructions

AMC-210 Transmitter with external electrochemical sensor

3.2 CABLE SELECTION AND WIRING

Connection should be made using 2-conductor, shielded cable. For best signal transmission

and maximum noise rejection, run cable through steel conduit (cable must be grounded at the

monitor or power supply). Supply voltage can be measured at the transmitter (–, +) connections

at the supply source. For basic cable selection, between the source and transmitter, use a 250-

ohm load resistance, use the following chart:

WIRE GAUGE AWG 22 20 18 16

@12VDC 1000 (305) 1500 (457) 2500 (762) 3800 (1158) MAXIMUM

DISTANCE IN

FEET (METRES)

@24VDC 15000 (4572) 23000 (7010) 38000 (11582) 57000 (17374)

For applications not covered by the above chart, an example is shown below for selecting the

right cable, using the graph of Figure 3 and the following formulas.

Note: Some non-AMC equipment may not

have the load resistance built in.

Example:

Calculations on the graph

Maximum resistance …. MR

Load resistance ………. LR

Known data

Power supply ………………………… 17 VDC

Load resistance ……………………… 180 Ohms

Wire gauge ……………………………20 AWG

Cable length / 1 Ohm resistance ….. 43.6 ft (13.3m) typical

Formula 1

: To determine remaining safe loop resistance.

Maximum resistance 518 Ohms (from Figure 3 graph)

Load resistance - 180 Ohms

Remaining resistance 338 Ohms

Formula 2

: To determine maximum safe cable length allowed.

Remaining resistance 338 Ohms

Cable length (for 1 Ohm) x 43.6 Feet

Maximum safe cable length 14,736 Feet

Note:

If maximum safe cable length is insufficient, increase the power supply voltage and/or

reduce the load resistance.