# Thread: 34902A Current Measurement

Replies: 3 - Pages: 1 - Feb 10, 2012 3:56 PM Last Post By: tomc Threads: [ | Next ]
 Posts: 19 Registered: 06/30/10
34902A Current Measurement
Posted: Jan 11, 2011 10:54 AM
 How do I measure current with the 34902A module for the 34970/72A?
 Posts: 19 Registered: 06/30/10
Re: 34902A Current Measurement
Posted: Jan 11, 2011 11:01 AM   in response to: stephen_mueller
 Unlike the 34901A module, the 16-channel 34902A module does not include a dedicated current measuring channel.Instead, add a user-supplied shunt resistor to the circuit and use a scaling equation to convert the voltage drop across the shunt to mA or the engineering units of choice. This same technique can be used to measure current on the non-dedicated current channels of the 34901A.The shunt resistor should be a low-value, high-precision resistor, placed in series with the circuit-under-test. Power dissipation and drift characteristics in the shunt should be considered. Accurately measure the resistance of the shunt so that a precise scaling factor can be calculated using Ohm's Law.The link below is a video demonstrating this technique of using a shunt resistor to measure current on a voltage channel.http://www.youtube.com/watch?v=Xfwl0MWbdJc
 Posts: 4 Registered: 10/18/11
Re: 34902A Current Measurement
Posted: Feb 10, 2012 12:01 PM   in response to: stephen_mueller
 Can the current measurement can be done for both AC and DC with a user provided shunt?
 Posts: 156 Registered: 01/12/11
Re: 34902A Current Measurement
Posted: Feb 10, 2012 3:56 PM   in response to: stephen_mueller
 With a user provided shunt, you measure ACV or DCV and divide by the known resistance to get the current. OR, you can use the built in scaling function to do this division.