3-3
DC power requirements
Note: These requirements assume a single transmitter per cable. Connecting multiple transmitters to
a single cable should generally be avoided.
If you are using DC power, the following requirements apply:
•
18–100 VDC
•
6 watts typical, 11 watts maximum
•
At startup, the transmitter power source must provide a minimum of 1.5 amps of short-term
current per transmitter.
•
Length and conductor diameter of the power cable must be sized to provide 18 VDC minimum
at the power terminals, at a load current of 0.5 amps. To size the cable, refer to Table 3-1 and
use the following formula as a guideline:
Minimum Supply Voltage = 18V + (Cable Resistance x Cable Length x 0.5A)
Table 3-1 Typical Power Cable Resistances at 68 °F (20 °C)
Gauge
Resistance
a
a. These values include the resistance of both high and low conductors in a cable.
14 AWG
0.0050
Ω
/foot
16 AWG
0.0080
Ω
/foot
18 AWG
0.0128
Ω
/foot
20 AWG
0.0204
Ω
/foot
2.5 mm
2
0,0136
Ω
/meter
1.5 mm
2
0.0228
Ω
/meter
1 mm
2
0.0340
Ω
/meter
0.75 mm
2
0.0460
Ω
/meter
0.5 mm
2
0.0680
Ω
/meter
Instruction and Operation Manual
X-CM-QmBS-eng
Part Number: 541B052AHG
June, 2008
Section 3 Installing Field-Mount Transmitter
QmBS Sensor / QTA Transmitters
