Emerson 2400S - Manual (Page 12)

8 Micro Motion ® Model 2400S Transmitters
Transmitter Orientation and Power Supply
2.5.1 DC power requirements for Model 2400S Analog and PROFIBUS-DP transmitters
If you are using DC power with a Model 2400S Analog or PROFIBUS-DP transmitter, the following
requirements apply:
• At startup, the transmitter power source must provide a minimum of 1 A 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 A. (This assumes a single transmitter per cable.
Connecting multiple transmitters to a single cable should generally be avoided.) To size the
cable, refer to Table 2-1 and use the following formula as a guideline:
2.6 Wiring the power supply
Note: This procedure is required only for Model 2400S Analog and PROFIBUS-DP transmitters.
To wire the power supply:
1. Remove the transmitter housing cover and user interface module as described in Section 2.4.
2. Unscrew the warning flap screw and raise the warning flap. Figure 2-3 shows the warning flap
in the open position.
3. Connect the power supply wires to terminals 9 and 10, as shown in Figure 2-3.
4. Ground the power supply to the transmitter’s internal grounding screw, shown in Figure 2-3.
5. Lower the warning flap and tighten the warning flap screw.
Table 2-1 Typical power cable resistances at 68 °F (20 °C)
Gauge Resistance (1)
(1) 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
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 =
MinimumSupplyVoltage 18V CableResistance CableLength
×
0.5A
Ч ( )
+ =