Siemens Pacemaker UM344-2 Instrukcja Użytkownika Pobierz pdf (Strona 42)

INSTALLATION UM344-2

September 1995

4.3.4 Power Supply Requirements

A power supply is needed to power the Transmitter(s). The power supply can be:

Ÿ A separate stand-alone supply capable of powering several Transmitters. It can be mounted in a

control room or in the field. Follow the power supply manufacturer's recommendations with regard to

mounting and environmental considerations.

Ÿ Located in a controller (such as a Primary Master) or other station able to safely provide additional

operating current and meet the power supply specifications of Section 8.3.2.

Determine needed power supply output voltage by calculating the Network Resistance and consulting

Figure 4-4. It shows the minimum power supply voltage needed for the calculated Network Resistance.

The total Network Resistance is the sum of the Current Sense Resistance, end-to-end Barrier Resistance

(if used), wire resistance, and any other resistances in the loop. The minimum Network Resistance (see

Glossary) required to support HART communications is 250Ω. The maximum resistance is 1100Ω.

FIGURE 4-4 Supply Voltage Versus Network Resistance

1650

1200

1100

1000

800

600

500

250

10V

12V

17V 20V 24V

30V 34V 40V

45V0

X02817S1

42V

Minimum Power Supply Voltage (VDC)

Network Resistance (OHMS)

OPERATING

REGION

1 2 ... 37 38 39 40 41 42 43 44 45 46 47 ... 182 183

Brak uwag

Siemens Pacemaker UM344-2 Instrukcja Użytkownika Strona 42