Flowserve 1000 Series Digitial Positioner Manual de usuario descargar pdf (Pagina 5)

Logix Series 1000 Digital Positioner

Installation, Operation and Maintenance Instructions

Flowserve Corporation 1350 N. Mountain Springs Parkway 1978 Foreman Dr.

Flow Control Division Springville, Utah 84663-3004 Cookville, TN 38501

www.flowserve.com Phone: 801 489 2233 Phone: 931 432 4021

FCD AXAIM0064-00 (AUTO-64) 08/04 Page: 5 of 16

Cable Requirements

The Logix 1200 positioner utilizes the HART Communication

protocol. This communication signal is superimposed on the

DC 4-20 mA current signal. The two frequencies used by the

HART protocol are 1200 Hz and 2200 Hz. In order to prevent

distortion of the HART communication, cable capacitance

and cable length restrictions must be calculated. The cable

length must be limited if the capacitance is too high.

Selecting a cable with lower capacitance/foot rating will allow

longer cable runs. In addition to the cable capacitance, the

network resistance also affects the allowable cable length.

In order to determine if the loop will support the Logix 1200

positioner, perform the following calculation.

Voltage =

The calculated voltage must be greater than 12 VDC in

order to support the Logix 1200 positioner.

Example: DCS Compliance Voltage = 19 VDC

barrier

= 300 Ω

wire

= 25 Ω

CURRENT

MAX

= 20 mA

Voltage = 19 VDC - 0.020 A*(300 Ω + 25 Ω)

= 12.5 VDC

The voltage 12.5 VDC is greater than the required

12 VDC; therefore, this system will support the Logix

1200 positioner. The Logix 1200 positioner has an input

resistance equivalent to 600 Ω at a 20 mA input current.

In order to calculate the maximum network capacitance,

use the formula shown in the next column. (NOTE: To

control cable resistance, No. 24 AWG cable should be used

for runs less than 5000 feet. For cable runs longer than

5000 feet, No. 20 AWG cable should be used.)

barrier

+ R

wire

+ 390)

Example: R

barrier

= 300 Ω

wire

= 50 Ω

cable

= =

Max. Cable Length =

Max. Cable Length = = 3636 ft.

network

(uF) ≤ - 0.0032

22 pF 0.000022 uF

foot foot

Compliance Voltage (@Current

MAX

)

- Current

MAX

*(R

barrier

wire

)

Current

Source

Logix

1200

Figure 7: Compliance Voltage

Figure 8: Field Termination

Field Terminations

HART Connection

Terminals

Housing EARTH

Terminal

Shielded

Cable

Connect Shield at Source

Ground

4-20 mA Current Source

(300 + 50 + 390)

0.08 uF

0.000022 uF/foot

network

(uF)

cable

- 0.0032 = 0.08 uF= C

network

(uF)(Max.)

(AXAIM0096-00) Logix 1000 IOM 8/6/04 3:34 PM Page 5

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