Oscilloscope Probe Maimum input voltage clarification

[babatundeawe]

Hi all;

Please i need a very good clarification in regards to the maximum input voltage of an osscilloscope.

i just bought one the Rigol1074z which came with the Rigol 2200 probe. the datasheet says at 10x maximum input voltage is 300ACV but i am not really cleared about this if it is RMS, Peak or peak to peak voltage.

so i tried mailing the Rigol support and here is the response I got

"The RP2200 probes that come with the DS1000Z series of scopes are rated as CATII probes with maximum voltage of 300VAC. This is 300V RMS. This does include any DC offset as well.

The maximum voltage is also frequency dependent. I have included the RP2200 specifications guide for your reference.

If you are going to be working with circuits that have amplitudes above 200V, it may make sense to use probes that have a higher voltage rating."

there are two things that are very unclear to me.

1. "This 300V RMS this does include any DC offset.

2. "If you are going to be working with circuits that have amplitudes above 200V, it may make sense to use probes that have a higher voltage rating. Does this means i cant use the probe on 10x to measure AC RMS voltage up to 300V

Here is the link to the datasheet of the probe

https://www.batronix.com/pdf/Rigol/RP2200.pdf

please help me out.

thanks

Tunde

 

[D.A.(Tony)Stewart]

1/4 W resistors are often rated like this for DC

Maximum Maximum Dielectric
Working V Overload V Withstanding V
250 350 500

For RMS take DC rating /1.4

If you want to work higher than rated cascading external resistors can be done with a voltage divider or for really high voltages, film caps rated for high Vac using a Capacitance divider.

What is your App.?

Normally passive insulators or dielectric or resistors are rated for 200 v/mm due to dust and humidity while air is ~1kV/mm to 3kv/mm unless dirty

 

[babatundeawe]

thanks sunny, i dont think i get where you re pointing me at, but what i am asking is about the maximum input voltage the scope probe whose datasheet i posted can whitstand without frying the scope or the probe?

thanks

tunde

 

[D.A.(Tony)Stewart]

The probe and scope limits are defined the choice of R size in each.

1/4 W is 0.3" body length as shown, HV R's or cascaded R's improve this.

In school we used 19 x 10Meg 1/4W R divider to 10M probe to measure 5kV with 200:1 result. To measure 100kV ac one uses a large PLastic cap rated at 100kV with a shunt cap rated at 1kV using a larger V ratio but in a larger value. A spark gap protects it. This how it is done commercially inside the bushing insulator.

 

[babatundeawe]

Thanks Sunnyskyguy. I am still threading on the part of caution and still trying to use the scope on low voltage, but really i actually bought it for troubleshooting on high voltage. I wish i could get a clear cut of what the probe is capable of. thanks.

tunde

 

[Orson Cart]

not more than 500V peak for your probes, for all probes the actual frequency response drops off with level, so you cannot see 300Vrms accurately at 100kHz, (actual will be higher)...

 

[babatundeawe]

@orson

Thanks, so its okay to use it to take samples upto 500vpeak at frequency below 100khz is that what you mean?

thanks

 

[Anna Conda]

I'm pretty sure Orson means that you can have +/- 500Vpk on your probes max, above that at your own risk, all probes suffer from reduced bandwidth at high AC voltages, you should have a graph from the probe maker for this, thus if you "see" 250Vac at 100kHz on/via your probes it will likely be higher than that in reality.

 

[babatundeawe]

Thanks bro,

I guess i am safe then. the highest i had gone so far in my power project is 25khz @250vAC rms and 50kHz @96Vdc.

though i have not tried sampling this on my scope because of fear of frying it. but i hope i am still within limits?

Anna the graph of the probe is attached to this post, please kindly have a look at it.
thanks.

tunde

 

[Orson Cart]

its all on the data sheet, if you had read it there would be no need for this post....

 

[babatundeawe]

Thanks Orson.

I guess the reason why we need teachers is to clarify what we dont know even after reading about it.

there wouldnt have been need for this post i understood what i read, and i guess i stated clearly this is my first experience using scope.

i am fortunate to get one, this things are not just what you will see everywhere in this part of my own world. so i have no experience with it. hence the need for these post.

thanks again, still looking for your more experience explanation, if any.

tunde