How "over-voltage protection block" work in NI-9225 and NI-9227?

[jennyzzz]

Hi all,

Hi, I am using NI 9225 and NI 9227 to collect data under high voltage.

According to the data sheet, the NI 9225 has an over-voltage protection and NI 9227 has an over-current protection.

I am wondering what kind of protections they each have, I mean, if high voltage or high current applied, what will happen to the hardware? Fuse is blown up? Or relay trip out? Can I re-open it after the voltage fault?

Thanks,

Jenny

[REDS · Accepted solution]

Hello Jenny,

We have an isolation IC that will protect some of the internal circuitry. There is no fuse or relay that you can replace. Because of that, if you go over the specifications (±450 VDC for the 9225 and 5 A RMS / 10 A RMS for 1s max with 19s cool down time at 5 A RMS for the 9227), then you will most likely damage your card. If you open up the module, you will lose the warranty for your device.

[jennyzzz]

Thanks for your answer!

But for NI 9225, why the overvoltage protection is 450 VDC, not Vrms? What does it mean?

[REDS]

Hello Jenny,

You're welcome! That is just the upper limit that the overvoltage IC that the card has handles. We just specify it as the OEM from the IC does. It means that the amplitude of the voltage shouldn't not exceed ± 450 Volts DC (~ 318 V RMS if the signal is a sine wave). RMS (Root Mean Square) is useful when you want to calculate the power of an AC (alternate current, means it varies over time) signal.

[jennyzzz]

Thanks,

BTW, how long can CRIO, NI 9225, and NI 9227 work continuously?  If I want to make a continuous acquisition for one week, can the equipment make it?

[REDS]

Hello Jenny,

cRIOs are made to work with no interruptions for a very long time and it shouldn't have any problems working for a week.

[Vikingyong90]

May I know will there be any interruption if I am using cDAQ with NI 9225 and NI 9227 instead of cRIO for 1 week measurement?

Hope for your guidance.

[REDS]

A week is not a lot of time and if the application is not that resource demanding and your computer doesn't crash, you could be running your code on a cDAQ with no problems. If you need your application to be on the field, to be headless and more reliable, go with cRIO.