Analog Input NI USB 6008

[prasan89]

In one of my machine, there having a NI USB 6008 device & it is damaged time to time due to burnt AI0 analog input. In the machine AI0 is used used to measure the current through 100mohm shunt resistance(max current to be meased is 6A) . the channel has been configured to get differential signal between the shunt resistor.

when it burnt. Path of both inputs AI0+ & AI0-  were burnt as shown in picture.

Maybe this is happend due to a back emf of the inductor.

How can i overcome this problem?? (whatever the modification, current measurement of this channel should be high accurate)

[Bob_Schor]

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@prasan89 wrote:

(whatever the modification, current measurement of this channel should be high accurate)

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Based on your specification of high accuracy, I would recommend replacing this device.  Look at the current crop of NI's USB offerings.  Also, learn how to set up measuring circuits to prevent further damage to the measuring device (I'm not a skilled Electrical Engineer, so I can't suggest how you should design the circuit to prevent "back EMF in the inductor" (what inductor?))..

Bob Schor

[herringbone]

If accuracy is what you are looking for, the USB 6008 is probably the wrong device for your application.

Read this white paper for more information about what NI recommends for power measuring devices.

http://www.ni.com/white-paper/8198/en/

[prasan89]

Thanks for your suggestions, but I cant change the NI6008 to a different type.. At the moment the current measurement of the NI6008 is adequate for my requirement.

What I want to know how to prevent the Device burnt from a inrush current

[Bob_Schor]

Go find an Electrical Engineer who knows her stuff and ask about "protective" circuitry.

Bob Schor