Emerson Process Management 8732 manual Requirements for 12-42 V DC Power Supply

Reference Manual

00809-0100-4663, Rev BA January 2010

Rosemount 8732

Requirements for 12-42 V DC Power Supply

Units powered with 12-42 V DC may draw up to 1 amp of current. As a result, the input power wire must meet certain gauge requirements.

Figure 2-4shows the supply current for each corresponding supply voltage. For combinations not shown, you can calculate the maximum distance given the supply current, the voltage of the source, and the minimum start-up voltage of the transmitter, 12 V DC, using the following equation:

Figure 2-4. Supply Current versus Input Voltage

	MaximumResis tance =	SupplyVoltage-------------------------------------------------------------------–12VDC-
			1amp
	0.9
	0.8
	0.7
(Amps)	0.6
	0.5
Current	0.4
Supply	0.3
	0.2

12 1824 30 36 42

Power Supply (Volts)

I = 10/V

I = Supply current requirement (Amps)

V = Power supply voltage (Volts)

Installation Category Overcurrent Protection

Connect Transmitter Power

The installation category for the Rosemount 8732 is (overvoltage) Category II.

The Rosemount 8732 Flowmeter Transmitter requires overcurrent protection of the supply lines. Maximum ratings of overcurrent devices are as follows:

Power System	Fuse Rating	Manufacturer
110 V AC	250 V; 1 Amp, Quick Acting	Bussman AGCI or Equivalent
220 V AC	250 V; 2 Amp, Quick Acting	Bussman AGCI or Equivalent
42 V DC	50 V, 3 Amp, Quick Acting	Bussman AGCI or Equivalent

To connect power to the transmitter, complete the following steps.

1.Ensure that the power source and connecting cable meet the requirements outlined on page 2-8.

2.Turn off the power source.

3.Open the power terminal cover.

4.Run the power cable through the conduit to the transmitter.

5.Connect the power cable leads as shown in Figure 2-5.

a.Connect AC Neutral or DC- to terminal 9.

b.Connect AC Line or DC+ to terminal 10.

c.Connect AC Ground or DC Ground to the ground screw mounted inside the transmitter enclosure.

2-7