Voltage Measurement varying between Devices?

[digi001]

Hi I'm looking to measure Voltage RMS but having trouble finding which device in my lab is most accurate.

I measure the same 440V Line to Line signal with a:

Tektronix DPO - 440V (Samples at 100,000Hz)
Fluke - 446V (Not sure)
Dranetz Power Analysis - 446V (Samples around 6000Hz)

What should I trust?

 

[FvM]

To compare results, a bandwidth specification may be required. It's meaningless to count e.g. MHz interferences for Vrms.

Oscilloscope specifications have limited accuracy by nature, e.g. 2%, this also applies to derived measurements. Review your manual. In so far, you should trust the dedicated voltage instruments, particularly the power analyzer.