Why is the voltage of AC380V measured with an oscilloscope, and the waveform shows a maximum of only

1. AC220V is the effective value, and its amplitude is generally about 311V; A high-voltage probe should be used to measure the AC380V, otherwise it will not only be inaccurate, but also dangerous.

2. An oscilloscope.

It is a very versatile electronic measuring instrument. It can transform the invisible electrical signal into a visible image, which is convenient for people to study the change process of various electrical phenomena. An oscilloscope uses a narrow, high-speed electron beam to create tiny spots of light when it hits a screen coated with a fluorescent substance.

This is how traditional analog oscilloscopes work). Under the action of the measured signal, the electron beam is like the tip of a pen, which can depict the change curve of the instantaneous value of the measured signal on the screen. The oscilloscope can be used to observe the waveform curves of various signal amplitudes with time, and it can also be used to test various amounts of electricity, such as voltage, current, frequency, and phase difference.

amplitude modulation and so on.

When measuring 220V AC with a visual wave, it is correct that its peak value is around 300V, because; 2x220=311V, but measuring 380V AC is not accurate, why?

I guess you measured one of the voltage probes on the neutral line, and then measured the three 380V lines, right?

I suggest that you connect the two measuring probes to the two 380V lines (A, B or A, C) respectively to measure the 380V alternating current.

Ordinary oscilloscopes cannot directly use ordinary voltage probes to measure mains, power electricity, inverters, etc., mainly because of the reference ground, TDS3000 series oscilloscopes are not isolated oscilloscopes, do not try, TPS2000 (non-TDS2000) is an isolated channel oscilloscope, which can be measured directly with ordinary probes, of course, Fluke Fluke190 series oscilloscopes, several Yokogawa oscilloscopes are isolated;

To measure these voltages, a differential voltage probe (such as the Tektronix P5200 series) can be used for ordinary oscilloscopes, which can solve the common ground problem;

In the past, in order to save costs, many old engineers unplugged the grounding wire of the power supply to measure the mains, so that the shell was not grounded, but the grounding clip line of the probe and the Q9 shell of the oscilloscope input were connected.

Have a great day!

My 2052 has a high gear of 200V, and the highest can measure 800V, but I haven't measured such a high voltage, he is used for signal measurement, ** It's not cheap, why do you measure 380V voltage?

According to you, the attenuation is two 10 times, which is equivalent to the voltage that actually reaches the oscilloscope, which can be measured!

But pay special attention: although this voltage reaches the oscilloscope, it is 220V at either end to ground! Do not come into direct contact with the human body during operation!

As long as the probe can be attenuated, it can.

The main purpose of using an oscilloscope is to display the waveform, to see what waveform, and whether there is distortion.

Although the voltage can also be measured, the error is large, especially when the voltage of the measured waveform is high, the error will be greater. As shown in the figure below, this is a standard sine wave, adjust the y-axis gain to make the amplitude of the waveform appropriate, and adjust the scanning frequency to make the waveform display stable.

The gear of the Y-axis gain knob indicates the scale of the waveform on the ruler, just like the scale of a map. In the figure below, the gears circled in red are 5 bars, i.e. in the y-axis direction, each bar is 5V. If the positive half cycle is 4 bars, it is 20V, and the negative half cycle is also 20V.

If the crest of the wave is not on the grid, it has to be estimated, so the error will be larger.

The physical formula for AC voltage is 2usin (2 f+) and all you measure is u, you have to use an oscilloscope to see the whole formula.

Wrong, alternating current changes over time, and the electrician base has it.

When measuring alternating current, the RMS value for one period is measured.

Possible causes:1The probe compensation is not adjusted properly, resulting in waveform distortion;

2.The impedance of the signal source and the oscilloscope is not matched, resulting in a large difference between the measured value of the voltage measurement and the true value;

3.The time base and amplitude range are not set well, and the waveform needs to fully occupy the oscilloscope screen to be accurate.

4.The oscilloscope is not calibrated and the self-calibration function of the system needs to be called up (see the user manual);

5.The oscilloscope is not well adjusted to trigger, and the reference level or trigger mode is not set well, resulting in a large error in the measured frequency;

6.The inferior quality of the cable (wiring) leads to a large loss of voltage;

7.The oscilloscope measures the voltage value as an instantaneous value, while the multimeter measures the RMS value, and the conversion needs to be calculated in between.

Measured using an oscilloscope.

Voltage and frequency, the reason why the measured value is very different from the true value:

The oscilloscope is not calibrated.

Before using an oscilloscope to measure voltage and frequency, it must be calibrated, and the calibration signal source can be used with the calibration signal that came with the oscilloscope.

The waveform of the oscilloscope is the instantaneous value of the continuous voltage displayed, and the voltmeter (or multimeter) measures the effective value, if you want to compare it with the measured value of the voltmeter (or multimeter), you must convert the corresponding effective value according to the waveform.

It is normal for there to be a voltage gap, and there may be a 30% error in the bandwidth. (The definition of bandwidth is.)

If there is a problem with the frequency, there is a large error, either there is a problem with your oscilloscope or a problem with the measurement method. The time base of the oscilloscope is generated by the local ** and is generally more accurate.

The voltage and frequency measured by the oscilloscope are instantaneous values.

Other tables measure valid values.

The probe has distributed capacitance, inductance, and input resistance, as for the effective value and average value, it is even more

Most general-purpose 10:1 probes are constructed to make them suitable for use with maximum input voltages of 400V or 500V peaks, so they can be used in a wide range of applications with signal levels up to hundreds of volts, and a higher voltage rating is recommended for field applications where higher voltages need to be measured.

The oscilloscope probe reads out.

Modern oscilloscope probes are equipped with a coding system that allows the oscilloscope to identify the type of probe that has been in line with it. This allows the oscilloscope to deflect the indication and all amplitude measurements vertically at high speed to avoid mud confusion. With a probe without this identification system, the user would have to redefine all waveform displays and measurements to reflect the attenuation of the probe.

Ground lead inductance.

Illustrates how the ground lead inductance of the probe forms a series resonant circuit with the input capacitance of the probe and oscilloscope. The input resistance of the probe introduces damping into the resonant circuit.

Oscilloscope probe equivalent circuit with ground lead inductance.

Like other resonant circuits, if a step voltage is added to the probe, the resonant circuit will ring, and excessive ground lead inductance will also worsen the rise time displayed by the oscilloscope, Figure 46 shows the display waveform of the fast rising edge pulse connected to the oscilloscope when different lengths of ground leads are used.

Effect of the ground lead on the impulse response.

From the figure, we can clearly see the influence of the ground lead inductance on the measurement results, so it is important to make the ground lead of the probe as short as possible, especially when measuring high frequency and fast rising edge signals.

Secure grounding. To ensure electrical safety, most oscilloscopes are connected to a safety ground wire via a power cord. It is possible but not necessary that the signal under test has the same reference potential as the ground wire, so care must be taken not to short-circuit a part of the system under test when connecting the probe's ground wire. On the other hand, even if the ground wire of the system under test and the oscilloscope have the same reference potential, this does not mean that the safety ground wire can be used as the signal return path, because the safety ground connection has a long trace and has a large lead inductance, so it is not suitable for the signal return path.

In this case, be sure to use the ground lead of the probe as the reference ground wire of the signal.

Oscilloscope probe type.

Both 10:1 and 1:1 probes have been studied, in addition to a number of other types of general-purpose probes.

Switchable oscilloscope probe.

This probe combines a 10:1 probe and a 1:1 probe into one, which is very convenient to use, and it is best to use 10:

1st gear, because the load effect of the probe on the circuit under test is small, and the frequency bandwidth is wide. The 1:1 step can be used to measure low-frequency and low-level signals.

Most of them only have voltages of 400PK or 600VPP, and we have also seen a maximum input voltage of 250V (such as SS5702), but these are not important, and the oscilloscope can measure voltages above 40kW with a dedicated probe.

Oscilloscope direct input.

The maximum voltage of BAI will basically be indicated at the entrance of the ZHI channel of the oscilloscope, and the input voltage of the SDS1102X-C is 400VPK. However, this is only the direct input voltage of the oscilloscope, often the oscilloscope also needs to be matched with a probe, in the case of a probe, the input voltage of the oscilloscope can be determined by the probe, and the high can be as high as thousands of volts or even tens of thousands of volts.

This should be viewed according to the oscilloscope self-energy of the body and the probe it used; For example, the standard voltage probe of Zhiyuan Electronics ZDS2022 oscilloscope has 300VRMS CATII level at X10 gear, that is, the maximum input voltage cannot exceed the RMS value of 300VRMS (the peak value of sine wave voltage is 848vpp). The vertical gear of the ZDS2022 oscilloscope is full of 8 grids, and the maximum gear is 10V DIV, so the input voltage cannot exceed 80V peak value, and the maximum input voltage with the X10 probe can reach 800VPP. Therefore, with the voltage probe that comes standard with the ZDS2022 oscilloscope, the input voltage peak-to-peak value cannot exceed 800vpp.