Bronkhorst EX-FLOW Mass Flow Manual de usuario descargar pdf (Pagina 19)

BRONKHORST HIGH-TECH B.V.

4 Cables

4.1 Introduction

An average two-wire cable has a capacity of 120 pF per meter and an inductivity of 0.67 µH/m.

For 100 m cable this results into:

cable

= 12 nF

cable

= 67 µH

4.2 Control system with XC coil

For the XC coil the capacity and inductivity is not important, but the voltage loss is the limiting factor.

The maximum voltage output of the controller is 14 Vdc.

14Vdc

65 Ohm

Control

circuit

For a two-wire shielded cable we don't want to allow more than 1 Volt loss.

So, on the coil

max

will be 13 Volt.

for XC I =

= =

200 mA

The cable resistance may be R =

0 2,

= = 5 Ω

A 0,25 mm

cable has a loop resistance of 1,6 Ω per 10 meter.

In other words: the maximum length is:

m3010

1,6

≈

cable dia max. length

0,25 mm

30 m

0,50 mm

60 m

0,75 mm

90 m

9.17.028 page 19

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Bronkhorst EX-FLOW Mass Flow Manual de usuario Pagina 19