Emerson 1700, 2700 installation manual DC power requirements

Installing the Transmitter

DC power requirements

Note: These requirements assume a single transmitter per cable. Connecting multiple transmitters to a single cable should 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 2-1and use the following formula as a guideline:

MinimumSupplyVoltage = 18V + (CableResistance ⋅ CableLength ⋅ 0.5 A)

Table 2-1Typical power cable resistances at 68 °F (20 °C)

Gauge	Resistance(1)
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 mm2	0,0136	Ω/meter
1,5 mm2	0,0228	Ω/meter
1 mm2	0,0340	Ω/meter
0,75 mm2	0,0460	Ω/meter
0,5 mm2	0,0680	Ω/meter

(1) These values include the resistance of both high and low conductors in a cable.

Example The transmitter is mounted 350 feet from a DC power supply. If you want to use 16 AWG

cable, calculate the required voltage at the DC power supply as follows:

MinimumSupplyVoltage = 18V + (CableResistance ⋅ CableLength ⋅ 0.5A)

MinimumSupplyVoltage = 18V + (0.0080 ohms/ft ⋅ 350 ft ⋅ 0.5A)

MinimumSupplyVoltage = 19.4V

8 Micro Motion® Model 1700 and 2700 Transmitters