Current Measuring using PLC

[ibnu973]

Hi,

I need a program for measuring the current consumption of Equipments ( Pumps, Compressor,etc). and data logging of these measurement should be done.

I need a PLC with a suitable program for measuring the current and data logging.

Type of Inputs used for the measurement.

and also would like to know if data logging can be done without using a program.

I hope someone could give a solution for my problem.

 

[sparkie]

Welcome to the forum. If you want to monitor the current of a piece of equipment:

If you want to measure current, you need what is called a "current transducer" to measure the current and send the data to your PLC.

The inputs will be 4-20mA to read the current in the line

Any PLC that can read the 4-20mA signal will do just fine

No you can not do this without using a program on the PLC. You will have to monitor the current and totalize the readings per your time frame

Good luck.

As a side note, if you want to log the data, you will also need some type of HMI program to read the data from the PLC, keep track of the data in a database and display the data.

 

[rdrast]

Sure you can do datalogging without a program. Strip and circular chart recorders are still available.

Do you really want to monitor just current? or actual power?

 

[AustralIan]

Sometimes, as well as current you want kWh.

Bechoff sell a card that has 3 voltage inputs (500VAC) and 3 current inputs (1A AC), which can be used directly with a current transformer. It calculates amps and power for you.

 

[gclshortt]

https://www.automationdirect.com/adc/Search/Search?fctype=adc.falcon.search.SearchFormCtrl&cmd=Search&searchquery=CURRENT+%26+VOLTAGE+SENSORS&categoryId=0&TxnNumber=-1&searchqty=10

Depending on the current and voltage that you are measuring, and the input of the PLC. You will probably need a current or voltage transducer. This is also referred to as signal conditioners.

Regards,

 

[Mispeld]

Another option on the sensing side are instruments from this company:

Load Controls Incorporated

We have used their power monitors for many years, and are satisfied with reliability and accuracy, particularly for motors with drives (less relevant now-a-days that you can get power directly via drive communications).

 

[jraef]

Given that you are in Qatar, your better choices are likely companies like Siemens, Schneider or ABB. All of them make and sell transducers that take power values and make them into signals that PLCs can read.

But as mentioned, you used the term "consumption" which implies you want to track energy. Current alone will not give you that, because current can vary with voltage. If what you want is to track energy consumption, then you need a watt transducer, which will read voltage, current and phase angle so that it can adjust the VA to watts.

 

[shooter]

check rishabh in india they sell power monitors (without use of PLC.
you can connect them to a PC an have excel sheets.

 

[Tom Jenkins]

These may be an option for you:

https://www.schneider-electric.com/en/product-category/4100-power-monitoring-and-control/

 

[Toine]

Wago have various modules for measuring current, check the various tastes of 750-494 and 750-495 modules. On the Wago global site:

Home > Products > Product catalog > Components for automation > Modular I/O-System (Series 750, 753) > Analog input modules


All do three channels. Can be used for separate items (e.g. checking current for 3 separate devices), or for a single 3-phase device. Current is either measured internally, with external shunts or Rogowski coils. Voltage can also be measured with the same module, and the combined values like apparent/active/reactive power, cosinus phi, harmonics etc

We have used some for various applications. One where a PLC checks total power consumption of a factory with solar panels on the roof. If power consumption goes negative (panels deliver more power than the factory uses), extra devices can be switched on and off automatically. E.g. charge electric forklift batteries over the weekend on the sunny afternoon when power is "free" rather than at night when every kWh costs.

In some projects we have motors that gradually demand more current because of dirt building up inside a machine. Monitoring current consumption of these motors helps to switch off for maintenance/cleaning before too much dirt causes damage to machine, gearbox or motors.

We programmed everything from the ground up. By now Wago have standard software for power monitoring, so should be easier these days.

 

[(8{)} ( .)]

I'm all with Toine regarding Wago especially since they've ported MySQL over to their PLCs. You can save the data locally and read and manipulated it over your system network. They've even got cloud connectivity if you want to log that way.

Good Luck,

Yosi

 

[qwemx]

https://www.youtube.com/watch?v=hikcIW5h0y8
you can use Siemens IO link master and current monitoring relays
and you have to use an HMI for logging

 

[tragically1969]

These may be an option for you:

https://www.schneider-electric.com/en/product-category/4100-power-monitoring-and-control/

I was just going to chip in and ask if anybody uses a power meter now !

Lots of solutions for just current but a $200 power meter and 3 CT's will give you a whole lot more information about whats really going on with the load, kW, kWh, pf, kVAr, THD etc etc......

 

[Saffa]

I was just going to chip in and ask if anybody uses a power meter now !

Lots of solutions for just current but a $200 power meter and 3 CT's will give you a whole lot more information about whats really going on with the load, kW, kWh, pf, kVAr, THD etc etc......

Completely agree. Schneider do a range of good little units with modbus RTU comms. I put in around 20 at one plant on everything bigger than 7.5kw. Found some inefficient pumps and modified our UV treatment dose pacing once i could show how much power we were wasting by running at fixed dose.

Also found the power factor correction had been set up wrong for 10 years.. CT ratio incorrectly specified and the system had been running 0.95 leading.

I track when dissolved oxygen probes need replacement better than from their calibration records... when blower power starts creeping up I go looking for sluggish probes