Re: [CAD_CAM_EDM_DRO] 4-20 mA signal

Sven Peter
A 4 to 20 madc signal requires what ever voltage to get 4 to 20 through the
resistance of the positioner coil.
If the coil resistance is 100 ohms, then 0.4 volts will give 4 ma (zero
percent of signal), 0.8 volts will give 8 ma (25 percent of signal), 1.2
volts will give 12 ma (50 percent of signal), 1.6 volts will give 16 ma (75
percent of signal), and 2 volts will give 20 ma (100 percent of the signal).
A 200 ohm coil will require twice the voltage (.8 to 4.0 volts), and a 500
ohm coil will require 5 times the voltage ( 2.0 to 10.0 volts) to get the 4
to 20 madc signal.
Dave Foreman
.

----- Original Message -----
From: "peteryco" <peteryco@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, July 17, 2002 06:52
Subject: [CAD_CAM_EDM_DRO] 4-20 mA signal


> Hello friends,
> it is a little while ago I didn't post because of a family
> arrangement. But today I need a little help on a off topic not so off
> topic theme.
> I got a pneumatical a steam valve into my shop that is
> governed by a 4-20 mA signal.
> I have to repair the positioning mechanism.
> No trouble with that, I did it quite a few times on other brands.
> But I do not know what is the standard voltage of the 4-20 mA
> signal for to make a pot-arrangement to simulate the PLC signal.
> There is no book arround to check.
> I would appreciate your help very much.
>
> Thank you
> Sven Peter
>
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