measuring current one CT multiple display

rajeshputta · Apr 30, 2016

i want to measure current from CT using multiple options.
at present my CT is connected to Analog Amps meter.
i want to plan for update to PLC AI at same CT connection point without removing old analog meter,
single CT point connection we can share both measuring methods?

Bit_Bucket_07 · Apr 30, 2016

You may place multiple devices in series from a current transformer, but you will diminish accuracy as you increase the impedance of the circuit. A better solution would be to convert the 0-5 AAC signal from the CT to a 4-20 mADC signal with a local transmitter and then place multiple devices in the 4-20 mA current loop.

rajeshputta · May 1, 2016

Bit_Bucket_07 said:
You may place multiple devices in series from a current transformer, but you will diminish accuracy as you increase the impedance of the circuit. A better solution would be to convert the 0-5 AAC signal from the CT to a 4-20 mADC signal with a local transmitter and then place multiple devices in the 4-20 mA current loop.

Thank you for your suggestion,
here i plan to use signal conditioner Action park model-6380-0000-1.
my CT range 600/5A.present it connected analog display meter([email protected])now i want to take connections at same point to my signal conditioner ? if take both will work?.
my plan is measuring current from CT by using PLC AI card,make a hard copy record & soft copy record.

danw · May 1, 2016

From the installation instructions:

"For current inputs above 100mA AC, it is recommended that an input shunt resistor be used and the AP6380 be configured for the proper input voltage range.

For example, for a 5A AC current transformer output, use the Action model C006 resistor (0.1W, 5W, 1%) and set the input for 0-500mV AC."

rajeshputta · May 1, 2016

danw said:
From the installation instructions:

"For current inputs above 100mA AC, it is recommended that an input shunt resistor be used and the AP6380 be configured for the proper input voltage range.

For example, for a 5A AC current transformer output, use the Action model C006 resistor (0.1W, 5W, 1%) and set the input for 0-500mV AC."

Yes, I ordered resister c006 too, with signal cinditiner,
And my question is possible to take multiple connecting ? From Using Same CT , analog meter+ Signal condition connection points.

danw · May 1, 2016

I don't know what impact a series resistance of 0.1 ohm has on an analog meter measurement. I doubt that it's much, but it's easy to test.

Put the 0.1 ohm resistor in series with analog meter and see what the effect it has. Short the resistor out with a length of wire and see if you can tell the difference between having the resistor in the circuit or when it is shorted out.

(Action Pak has misprinted the specs for the resistor. The resistor is a 0.1 ohms (not 0.1W), 5 watt, 1% resistor (0.5V = 5A * 0.1 ohm)

Tom Jenkins · May 3, 2016

Most C/Ts provide a 0-5 Amp AC output. An analog ammeter is a very low burden device - typically the wiring is more resistance (burden) than the meter.

When I have done this in the past I just use a clamp-on amp transmitter on the C/T output.
http://www.automationdirect.com/adc...ansducers/AC_Current_Transducers/ACT005-42L-S

You don't have to open or modify the existing circuit or mess with the old wiring or meter. There is no additional burden on th C/T. Scale your PLC so that at 20 mA transmitter output matches the initial C/T max.

rajeshputta · May 7, 2016

Tom Jenkins said:
Most C/Ts provide a 0-5 Amp AC output. An analog ammeter is a very low burden device - typically the wiring is more resistance (burden) than the meter.

When I have done this in the past I just use a clamp-on amp transmitter on the C/T output.
http://www.automationdirect.com/adc...ansducers/AC_Current_Transducers/ACT005-42L-S

You don't have to open or modify the existing circuit or mess with the old wiring or meter. There is no additional burden on th C/T. Scale your PLC so that at 20 mA transmitter output matches the initial C/T max.

My CT range 600/5A
it connected & measuring Amps Analog meter (class 2.5)
i want to connect PLC anlalog input card+ using signal conditioner.
it possible same CT to for two measuring device? and we take same wiring point?

Tom Jenkins · May 7, 2016

Like this:

measuring current one CT multiple display

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