Emerson Power SUPPLY/CURRENT Loop, Model 5081-T-HT, Power Supply-Current Loop Wiring

MODEL 5081-T	SECTION 2.0
	INSTALLATION

2.4POWER SUPPLY/CURRENT LOOP

— MODEL 5081-T-HT

2.4.1Power Supply and Load Requirements. Refer to Figure 2-3.

The minimum power supply voltage is 12.5 Vdc and the maximum is 42.4 Vdc. The top line on the graph gives the voltage required to maintain at least 12.5 Vdc at the transmitter terminals when the output signal is 22 mA. The lower line is the supply voltage required to maintain a 30 Vdc ter- minal voltage when the output signal is 22 mA.

The power supply must provide a surge current dur- ing the first 80 milliseconds of start-up. For a 24 Vdc power supply and a 250 ohm load resistor the surge current is 40 mA. For all other supply voltage and resistance combinations the surge current is not expected to exceed 70 mA.

FIGURE 2-3. Load/Power Supply Requirements

For digital (HART or AMS) communications, the load must be at least 250 ohms. To supply the 12.5 Vdc lift off voltage at the transmitter, the power supply voltage must be at least 18 Vdc.

For intrinsically safe operation the supply voltage should not exceed 30.0 Vdc.

2.4.2 Power Supply-Current Loop Wiring.

Run the power/signal wiring through the opening nearest terminals 15 and 16. Use shielded cable and ground the shield at the power supply. To ground the transmitter, attach the shield to the grounding screw on the inside of the transmitter case. A third wire can also be used to connect the trans- mitter case to earth ground.

NOTE

For optimum EMI/RFI immunity, the power supply/output cable should be shielded and enclosed in an earth- grounded metal conduit.

Do not run power supply/signal wiring in the same conduit or cable tray with AC power lines or with relay actuated signal cables. Keep power supply/ signal wiring at least 6 ft (2 m) away from heavy electrical equipment.

An additional 0-1 mA current loop is avail- able between TB-14 and TB-15. A 1 mA cur- rent in this loop signifies a sensor fault. See Section 3.0 for wiring instructions. See Section 8.4 or 10.6 and Section 12.0 for more information about sensor faults.

Refer to Figure 2-4.

FIGURE 2-4. Model 5081-T-HT Power Wiring Details

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