Which type of V/A sensor suitable for the use of SCC -2345?

[TARC]

Which type/brand of Voltage/current sensor suitable for the connection of SCC -2345?

[Ed W]

Hi TARC,

There are a lot of options for measuring voltage or current in the National Instruments SCC series.  These are listed below, with the link to NI’s website where these modules can be found.

2 Channel Voltage Input Module:

·         SCC-AI01, 2 Channel Isolated Analog Input (42V, 10 kHz)

·         SCC-AI02, 2 Channel Isolated Analog Input (20V, 10 kHz)

·         SCC-AI03, 2 Channel Isolated Analog Input (10V, 10 kHz)

·         SCC-AI04, 2-Channel Isolated Analog Input (5V, 10 kHz)

·         SCC-AI05, 2-Channel Isolated Analog Input (1V, 10 kHz)

·         SCC-AI06, 2 Channel Isolated Analog Input (100 mV, 10 kHz)

·         SCC-AI07, 2 Channel Isolated Analog Input (50 mV, 10 kHz)

·         SCC-AI13, 2 Channel Isolated Analog Input (10V, 4 Hz)

·         SCC-AI14, 2 Channel Isolated Analog Input (5V, 4 Hz)

2 Channel Current Input Module

·         SCC-CI20 2-Channel Current Input Module, 0-20 mA

2 Channel Voltage Attenuator Module

·         SCC-A10 2-Channel Attenuator Input Module, 10-to-1

These modules will work with any standard transducer.

Hope this helps!

Ed Waxler | Applications Engineering |  National Instruments

[TARC]

Hi Ed W,

ok..thx, it helps alot...I choosen to use a SCC-AI03, 2 Channel Isolated Analog Input (10V, 10 kHz) and a SCC-CI20 2-Channel Current Input Module, 0-20 mA.But i still need to connect V/A sensor or transducer to it so that signals can be send into the SCC to be analyzed, right?( correct me if i am wrong).

[Ed W]

Hi TARC,

The voltage and current input modules provide signal conditioning for your sensor/transducer.  The idea is that you supply the signal (whether it be from a thermocouple or strain gauge, etc.), and the National Instruments’ products will provide the hardware to acquire and condition that signal.

Ed Waxler | Applications Engineering |  National Instruments

[TARC]

Hi Ed W,

Lets say i am doing analysis about power quality, that mean i just need to use a step down transformer to step down the voltage to 10v, 0-20 mA and connect the output of the transformer to the SCC-2345 (SCC-AI03, 2 Channel Isolated Analog Input (10V, 10 kHz) and a SCC-CI20 2-Channel Current Input Module, 0-20 mA) ??

TARC | Student

[Ed W]

Hi TARC,

That sounds like it should be fine.  Just check the specifications on your transformer to verify that the signals are in an acceptable range for the National Instruments products.

Ed Waxler | Applications Engineering |  National Instruments

[Buechsenschuetz]

It depends whether you want to measure AC voltage/current or DC voltage/current.

You can use a transformer to step down voltage from an AC circuit (assuming that it is a common 50Hz or 60Hz circuit). But a transformer usually is used to transfer power, and its frequency range is pretty limited so probably RF spikes will be suppressed by the transformer and you won't see them on your acquisition device.

If you have a board with true isolated analogue inputs you can use a simple voltage divider to reduce the voltage to the input range of your board.

To measure current it might be a better choice to use a low-ohm shunt and to measure the voltage drop across the shunt. Usually shunts are designed to give a full range output of 60mV or 100mV at their rated current.

You can use both methods to measure DC voltage and/or current, too.

If you do not want to insert a shunt in your circuit under test you can also use a current clamp probe. Many of them are suitable for AC only, but some manufacturers like LEM also offer DC current clamps.

BTW you don't have to bother with the 4-20mA inputs of your boards. Most transducers have a voltage output, and if you set your input(s) to voltage mode and a suitable range they will work fine.