Current Transducer 0-20mA

Thread Starter

sandeep reddy_1496663996

Joined Jun 5, 2017
3
I want to feed my current to a PLC., I have multiple outgoings for which i should be taking transducers for each ( Current transformer + current transducer) i have like 20ckts for which i want to monitor the current., i want to reduce the cost of the system., is there any other way where i can use other circuits for this applications.
Links with products are highly appreciated.

thanks in advance.
 

Reloadron

Joined Jan 15, 2015
5,882
I am not sure I understand exactly what you have and what you want? Does your PLC allow for a 0 - 20 mA input or 4 - 20 mA input? You have outputs from transducers for example converting pressure, temperature, flow or other forces to a 0 - 20 current loop? Would that be what you have? My systems just used a voltage input so I used resistors in my current loops for example with a 250 ohm resistor 4 - 20 mA = 1 to 5 Volts or using a 500 ohm resistor 4 - 20 mA = 2 to 10 Volts. If you better explain exactly what you have and what you want I am sure there will be solutions.

Ron
 

EM Fields

Joined Jun 8, 2016
583
I want to feed my current to a PLC., I have multiple outgoings for which i should be taking transducers for each ( Current transformer + current transducer) i have like 20ckts for which i want to monitor the current., i want to reduce the cost of the system., is there any other way where i can use other circuits for this applications.
Links with products are highly appreciated.

thanks in advance.
Please post:
1. AC or DC currents?
2. Current transformer / transducer data sheets.
3. System schematic / block diagram.
4. What are the "outgoings" coming from?
5. What does your PLC want to see?
 

Thread Starter

sandeep reddy_1496663996

Joined Jun 5, 2017
3
I am not sure I understand exactly what you have and what you want? Does your PLC allow for a 0 - 20 mA input or 4 - 20 mA input? You have outputs from transducers for example converting pressure, temperature, flow or other forces to a 0 - 20 current loop? Would that be what you have? My systems just used a voltage input so I used resistors in my current loops for example with a 250 ohm resistor 4 - 20 mA = 1 to 5 Volts or using a 500 ohm resistor 4 - 20 mA = 2 to 10 Volts. If you better explain exactly what you have and what you want I am sure there will be solutions.

Ron
I have a 3phase 4-wire system with Voltage - 415V, Current - 200A.,
Now i want to feed these inputs to a controller which allows 0-20mA inputs.
 

profbuxton

Joined Feb 21, 2014
419
So you have a 4 wire 3 phase 200A system and you want to measure the currents(in each phase , I presume). Just get suitable current transformers that can provide a 4-20mA output. I' m sure its not all that difficult. Its done all the time in SCADA systems.
 

Reloadron

Joined Jan 15, 2015
5,882
Ohio Semitronic as mentioned and CR Magnetics is another. Since you mention 4 - 20 mA I assume you want to accurately measure the current. You also have a choice of average responding RMS indication or RMS responding and RMS indicating. When measuring relatively clean sine waves the less costly average responding is a good choice. If you want less cost then I suggest basic Current Transformers and you build or buy a transducer to work with your current transformer. A CT (Current Transformer) is inexpensive but will require signal conditioning on your part. A simple Google of Current Transformers should bring up a few dozen results and manufacturers.

Ron
 

Reloadron

Joined Jan 15, 2015
5,882
I read your other thread where you mentioned :
I have 415V , 200A 3 Phase wire system., Now i want to feed this inputs to a Controller which allows analog data of 0-20mA.
We can use control transformer (200A to 5A)+ Control transducer (5A to 0-20mA).

But these are costly as well as consuming lot of space.,
Is there any other way where i can get the desired outputs with minimal costs as well as space.
Yes, you can use a simple ratiometric current transformer. I mention that above. The problem with this method is that Current Transformers typically have a ratiometric output for example a 200:5 would have 5 amps on the secondary with 200 amps passing through it (the primary) that 0 to 5 amps then needs signal conditioning as you have 0 to 5 amps AC at your mains frequency. Current transformers are designed to work into a "burden resistance" Calculation of the Current Transformer Accuracy Limit Factor is a good read on selecting a burden resistance. Then it comes down to Precision Rectifier Circuit for CT Signal Conditioning to get from what you have to what you want. The simple process is to buy an off the shelf solution and at no point do you define inexpensive or expensive?

Ron
 
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