The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
Wow, that was close!
by jraef
11/28/16 07:06 PM
Earthquake in New Zeeland
by RODALCO
11/27/16 11:25 PM
Calling all Non-US members!! (Non-US only)
by Tjia1981
11/27/16 06:33 AM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 10
Texas_Ranger 8
Trumpy 8
sparkyinak 7
Who's Online
1 registered (LongRunner), 206 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#173914 - 01/22/08 06:54 PM 4-20ma Pressure Transmitter
Cinner Offline
Member

Registered: 12/01/04
Posts: 77
Loc: Kelowna, B.C., Canada
Does anyone have any industrial experience with pressure transmitters. My question is this: If the voltage is 10 - 30 V DC and the output is 4-20ma, would this require 4 wires to connect( 2 for the voltage and 2 for the 4-20ma output). Can the transmitter run on only 2 wires?

Top
Work Gear for Electricians and the Trades

Work Gear for Electricians and the Trades
Work Gear for Electricians and the Trades
Arc Flash Clothing, Gloves, KneePads, Tool Belts, Pouches, Tool Carriers, etc. etc....

#173915 - 01/22/08 07:07 PM Re: 4-20ma Pressure Transmitter [Re: Cinner]
bigrockk Offline
Member

Registered: 01/25/03
Posts: 175
Loc: Middle of Canada
Yes it can work with only two wires. This is fairly common.

Positive transducer lead to positive of power supply. Negative of power supply to negative side of "load" . Positive side of load to negative lead on transducer.
So essentially it is just a loop.

The load could be many things such as a plc controller a meter or readout of some type etc.


Edited by bigrockk (01/22/08 07:15 PM)
Edit Reason: To add more info

Top
#173952 - 01/23/08 11:44 AM Re: 4-20ma Pressure Transmitter [Re: bigrockk]
NJwirenut Offline
Member

Registered: 09/15/01
Posts: 816
Loc: Bergen County, NJ
4-20 mA control loops are very common in industrial control gear. In the 2-wire configuration, the transmitter is actually powered by the voltage drop across it.

A good introduction to current loop sensors here:

http://www.datel.com/data/meters/dms-an20.pdf

Top
#173973 - 01/24/08 08:06 AM Re: 4-20ma Pressure Transmitter [Re: NJwirenut]
JValdes Offline
Member

Registered: 06/03/07
Posts: 308
Loc: South Carolina
How many terminals do you have on the transducer? And do you have the wiring diagram for it? Normally you will have an input 2 wires (10-30vdc) and an output 2 wires (4-20ma). Two in. Two out. No common. To test the output MA, put meter in series with one output conductor. Use the MA setting on the meter. Depending on how sensitive you need this, you may need to adjust the DC input or if provided the adjustment screw on the transducer.

Top



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals