# I am using the TPS2024 with the current probe A622. The scope is measuring the charging current of a capacitor+ the reading of the RMS and Frequency is not shown and all that is displaying are question marks. What is the set up so the scope can make these measurements?

### 問題：

I am using the TPS2024 with the current probe A622. The scope is measuring the charging current of a capacitor+ the reading of the RMS and Frequency is not shown and all that is displaying are question marks. What is the set up so the scope can make these measurements?

### 答案：

The best solution is to use the TPS2PWR1 Power Measurement Application software module.

Using the Power Application module we find the Cycle RMS value, 383 mV, and Frequency is 60.02 Hz If you do not have the Power Application module a work around for the frequency is to use the Trigger Frequency readout. Note the lower right corner of the display. The Frequency reading is 60.0010 Hz.

The Cycle RMS value for the same waveform can be derived by:

1. duplicating the waveform on ch2,
2. making sure that there are an integral number of waveforms on the screen (or at least 10 total cycles),
3. turn Math Multiply on with the source set to Ch1 & Ch2,
4. using the Measurement Menu turn on the Mean value of the Math channel.
5. take the square root of the Measured Math Mean value. The square root of 196 mVV, SQRT(0.196), is 0.443 V, or 443 mV.