Rational use of differential probes

High-voltage differential probes are commonly used measurement methods for power engineers, but compared with ordinary probes, the use of high-voltage differential probes has many details.

Use a high-voltage differential probe to measure the voltage of the 220V (about 620V peak) power module. The main considerations are as follows:

Before measuring, it is necessary to know how much the peak voltage of the power supply is and whether it is beyond the scope of the probe. In order to ensure the safety of users, this product and the equipment connected with this product, please strictly abide by the following safety operation procedures:

Use the correct power adapter: The original power adapter must be used to avoid damage to the probe.

Before measuring, check whether the selection of the probe gear is correct. If the voltage peak range is lower than 130v, 1/50 gear can be used. If the voltage peak range is higher than 130v, it is recommended to use 1/500 gear. The corresponding oscilloscope should also be replaced with the corresponding probe ratio, 50x/500X. When adjusting the oscilloscope in the oscilloscope, try to set the appropriate vertical sensitivity of the oscilloscope so that the waveform can occupy up to 6 squares on the screen, but do not exceed the screen range. Because the smaller the waveform vertical gear, the higher the measurement accuracy of the ADC, the higher the measurement accuracy.

When measuring, the twisted input line should be used as much as possible. The use of twisted pair can reduce the area of the coil and the pickup of the spatial magnetic field, thereby reducing the interference of noise and improving the measurement accuracy. Especially in the environment of strong electromagnetic radiation, the use of twisted pair can effectively reduce noise interference.

Try not to use an extension cord. The extension line will increase the input capacitance, produce signal reflection, reduce the bandwidth of the probe, and make the high frequency signal impossible to measure. When the measurement frequency exceeds 10MHz, it is not recommended to use an extension cable. If additional extension of the input line is required, the two extension lines should be extended for the same length, and the signal frequency of the measurement input should not exceed 10MHz.

The extension of the input line has a certain effect on the voltage amplitude. When using extension wires, it is recommended that the two input wires be twisted in pairs, so that more interference can be avoided and the measurement effect is better.