# Sensing high voltage of a triangle wave

I have an Arduino Uno and would like to check the frequency, voltage and current of a triangle wave. The problem is its at a higher voltage of about 1400v DC. Are there any sensors that can directly work with this voltage level? Even if it just returned a Vavg of 700V that would help too. Would a current sensor properly average the current like a cheap analog ammeter would? The current range will be in the few hundreds of mA's. Anyone know how I might be able to read the frequency?

Heres the waveform I need to obtain as much info as possible for in real time:

Those are EXTREMELY DANGEROUS voltages and currents. If you don't have much knowledge or experience with the APPROPRIATE use of voltage dividers, high voltage capacitors and high voltage isolation circuitry, please leave this task to someone who has that experience.

Firstly 1400V at several 100mA is utterly lethal, so you will have to be extremely careful working with this.

A voltage divider is possible, use 3 high voltage 1M 0.5watt resistors in series in the upper arm of the divider and 10k in the lower arm of the divider .

Its crucial to use high voltage resistors (they are longer and prevent high-voltage flashover), and to use at least two so there is no single point of failure. They need to be at least 0.5W rated and will get hot.

With 3 1M resistors in the upper arm the current will be 470uA which is still problematical should the lower arm go open-circuit - use two 20k resistors in parallel perhaps.

10k / 3M = 0.0033, so 1400V is reduced to 4.67V

Thanks for the tips. I thought there might be an easier or more straight forward way to do it.

If I just wanted to measure current wouldn't any sensor do it? Because voltage does not matter much? For example an ACS712: https://www.sparkfun.com/products/8883

Because voltage does not matter much? For example an ACS712: https://www.sparkfun.com/products/8883

The current sensor output circuitry must be well isolated from the high voltage (I suggest 3000 V absolute minimum) to prevent destruction of your measurement circuitry and/or yourself. You should ask the SparkFun engineers about the isolation voltage of that breakout board, but I personally would not risk using it.

kenw232:
Thanks for the tips. I thought there might be an easier or more straight forward way to do it.

If I just wanted to measure current wouldn’t any sensor do it? Because voltage does not matter much? For example an ACS712:
https://www.sparkfun.com/products/8883

The ACS712 is rated for 2.1kV rms isolation (but note that you’d need to
take precautions against flash-over on the PCB, such as potting the high voltage
side in silicone and milling apropriate slots *).

Note that other current sensors in that range are not high voltage rated - the
ACS711 for instance is rated for < 100V… Be very careful.

• in humid conditions flashover will happen at a low lower than 1.4kV - normal
PCB surfaces aren’t up to it, conformal coatings and potting are probably needed,
enough distance is needed to separate parts of the circuit. If in doubt do not
proceed with this kind of voltage…

rms ratings are for AC. You have identified the signal you want to measure as DC. Please don't discuss AC in a DC application, it is just a waste of time.

Well, yes, and no. If you connected that "DC" waveform to any sort of load, and wanted to calculate the power being used or dissipated by the load, it is an "rms" calculation that you would actually be doing.

Wouldn't AVERAGE POWER be more appropriate ?

raschemmel:
Wouldn’t AVERAGE POWER be more appropriate ?

No.
You want the equilivent power that a DC excitation of the load would give and that is what RMS gives you.