Chapter 8 Tutorial

Measurement Fundamentals

m

Tz z ai ABG89R 6

 

I q°°u uu u su”yw wx yus

qy°qw q yuu y y°y

 

° sus y u u syyyw °uqut

 

sx qu wx r u °u qt u sy

 

I y2 b

y yqw sus qs

 

°ysx ” t u

 

y ”us q yr”u °yy°y u

wuuq4 dxu q”

b

instrument’s “ z

, or bk drop. This voltage drop is sensed by

the internal MWW and scaled to the proper current value to complete

the measurement (

).

On-Card

S1

Fuse

 

 

 

 

 

 

 

S

RS

LO

+/- Vdc to Input Amplifier and Analog-to-Digital Converter

AC current measurements are very similar to dc current measurements. The output of the current-to-voltage sensor is measured by an ac voltmeter. The input terminals are direct coupled (ac+dc coupled) to the shunt so that the internal MWW maintains dc continuity in the test circuit. Performing ac current measurements demands additional care.

The “z

(loading) varies with frequency and input inductance,

often causing unexpected behavior in the test circuit (

z

).

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Image 363
HP 34970A manual On-Card