It is generally difficult for multimeter to detect burr signal in AC signal, as what multimeter detects is the value at a certain time point. When the multimeter converts digital to analogue, the sampling point may not be the burr peak, so the test result can not reflect whether there is burr in the waveform signal. For detection by oscilloscope, what detects is continuous waveform generally, and the MAX/MIN value can be captured through oversampling, thus the burr signal will be displayed.
The MCU control chip is damaged, please send the multimeter to manufacturer for maintenance.
Because the air is moist and the moisture content in the vaseline applied on the PCB pad increases. Please wipe out the vaseline on the PCB pad and apply new vaseline, or perform measurement when the air is dry.
Clamp the single core when performing current measurement through clamp meter, the clamp meter calculates the current by inducing surrounding magnetic fields. If live and neutral wires are measured together, the directions of magnetic fields of both wires will be offset, so the measured current is zero constantly. Please clamp a live wire by the clamp jaw to perform current measurement.
Because the sensitivity of camp jaw is relatively poor and large error will occur when performing measurement of small current through clamp meter with large range. It is recommended to use clamp meter with small range.
For AC current measurement:
It is affected by electromagnetic field. The clamp jaw is designed with hall component (a sensitive device), sensitive with magnetism, heat and mechanical stress to some extents. When the clamp meter is interfered by the electromagnetic field in the measurement environment, the reading will be changed or can not be reset.
For DC current measurement:
After measurement of large current, there will be residual magnetism at the clamp jaw for some time, and the least significant digit will be displayed on the LCD. Please long press REL to reset the reading.
The measurement amplitude at frequency gear is between 100mV and 30V typically, 220V is out of the amplitude, it is recommended to switch to power frequency gear.
Models to support frequency measurement at voltage gear:
For peak measurement: Maintain the MAX/MIN value of pulse signal automatically, the response time of logging MAX/MIN peak value is short (about 250us), a transient value can be measured accurately through this function. Peak voltage and current can be observed at the moment of startup of equipment.
For MAX measurement: It refers to the maximum value within a certain time.
The accuracy can be guaranteed at 10% of the range, for example, if the minimum range at AC current gear of UT211A is 600mA, the minimum current that UT211A can measure will be 60mA.
Low pass filter is built in clamp meter with LPF function, typically, this function is used to measure PWM output signal of frequency converter, the high frequency will be filtered during measurement so as to measure signal of fundamental wave.
1. The frequency converter will interfere the electric circuit at a high frequency for variable-frequency motor.
2. Be sure that voltage and frequency can be measured accurately for variable-frequency drive.
Due to the design of the multimeter, a reference value is needed when measuring large resistance (200M) through multimeter with old design, so a resistance value will be displayed. 1M for 1999-count multimeter, 10M for 19999-count multimeter, this value should be subtracted.
NCV refers to Non-Contact Voltage Detection.
To detect if AC voltage or electromagnetic field exists, bring the front end of the clamp meter to get close to the measured conductor, if the voltage of electric field is greater than the specified voltage (100V), the buzzer will make sounds and the LED will flash or lights up constantly.