0
\$\begingroup\$

The power supply of many oscilloscopes and other test equipment from different manufactures are commonly rated for 400 Hz operation. For example, Tektronics MDO3000 is rated to work at 400 Hz at 115 VAC. Rigol MSO7000 is rated at 100-240 VAC, 45 Hz-440 Hz.

I'm aware that 400 Hz power supply is widely-used in aerospace, and I heard some military and industrial installations also use 400 Hz, mainly to reduce the weight of the transformer. But I didn't find any specific case online.

What are some specific scenarios when users are expected to connect the oscilloscope to a 400 Hz power supply? Using an oscilloscope on a flying aircraft sounds unplausible. Most laboratories, industrial or otherwise are likely supplied with 50/60 Hz AC to power all equipment. The only possibly I can think of is field-engineers doing tech support. But even then, I believe it's more common to use a portable, battery-powered oscilloscope.

Does anyone who has an industrial background can explain: Is that really difficult or inconvenient to find a standard mains-frequency power in some factories to make it justified for most oscilloscope manufacturers to rate their scope for 400 Hz operation?

\$\endgroup\$
3
\$\begingroup\$

Yes that’s what it means. Planes often use 400 Hz generators and the plane’s frame becomes “Earth ground”.

As always, Gnd just means 0V anywhere in the universe and Earth bonded implies 0V to earth ground with some impedance <100 Ohms each to another grid location with an earth ground, unless in dry remote areas with poor earth bonding.

Earth is used by all 3 pin instruments to bypass EMI line filter leakage currents only and provide a good low impedance reference for scope probe ground leads.Sometimes DSO’s will put a plastic cap or an inductor between 0Vdc and Earth gnd pin for various reasons to isolate earth ground common mode RF noise (L), or block AC current but bypass RF to a relatively low impedance AC gnd using a cap only.

Engineers do use DSO’s on planes for R&D work.

\$\endgroup\$
  • 1
    \$\begingroup\$ "Engineers do use DSO’s on planes for R&D work" Wow, how common is it? Do they use it for maintenance? Developing a device related to aircraft? Or is it that sometimes the schedule is so tight that you need to do R&D on planes during your business trip? \$\endgroup\$ – 比尔盖子 Jun 29 at 23:22
  • 1
    \$\begingroup\$ Aircraft testing is done in the flying thing. Same as train and car testing. It's done in the running thing. \$\endgroup\$ – Janka Jun 29 at 23:25
  • 1
    \$\begingroup\$ dont' forget ships... ships do run on 400Hz as well because most of the time they use a jet engine for propulsion \$\endgroup\$ – JonRB Jun 29 at 23:26
  • 1
    \$\begingroup\$ Nah, they were interested but I started my own business instead. \$\endgroup\$ – Janka Jun 29 at 23:36
  • 1
    \$\begingroup\$ The military in general uses 400 Hz 3-phase where possible just to get the extra efficiency from downstream ferrite-core transformers. \$\endgroup\$ – Sparky256 Jun 30 at 1:32

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.