|What are the AC and DC analog signal output of UT352 sound level meter?|
UT352 can output DC and AC signals at the same time. The DC interface outputs DC voltage signals. And the voltage is proportional to the noise value. It can be used for the secondary calibration of data or display equipment expansion. The AC interface outputs AC voltage signals and can be used for spectrum analysis of environmental noise.
|What do A weighting and C weighting of UT352 sound level meter stand for?|
Human hearing has different sensitivity at different frequencies. To simulate this feature, a network inside the product corrects electrical signals to resemble human hearing.
A weighting simulates the human ear response to sound, so that the middle and low frequency bands of electrical signals have a large attenuation.
C weighting simulates the frequency characteristics of high intensity noise.
|What kinds of materials can the coating thickness gauge measure?|
The coating thickness gauge can measure the thickness of magnetic or non-magnetic coatings (such as aluminum, chromium, copper, enamel, rubber, paint, etc.) on magnetic metal substrates (such as steel, iron, alloy and hard magnetic steel, etc.) ,and the thickness of non-conductive coatings (such as enamel, rubber, paint, plastic, etc.) on non-magnetic metal substrates (such as copper, aluminum, zinc, tin, etc.). It is a necessary meter for automobile manufacturing, sales, evaluation and metal processing, coating, inspection and other industries.
|How to disable the auto power off function of UT333/UT333BT?|
Press and hold the HOLD and ON/OFF buttons at the same time to disable the APO function. And “APO OFF” will show on the LCD.
|How to change the system language of UT387 series to English?|
If the system language is Chinese after turning on the product, long press the Foreign Material Detection button (red) and the Power button (yellow) until the screen turns black. And then long press the Power button (yellow) to change the system language to English. To switch from English to Chinese, please follow the above steps.
|Why cannot the reading be reset and unstable for mV measurement?|
This is because the input impedance for mV measurement is high, typically at a level of GΩ, leading a strong drive capability to the voltage source. On the condition that the test leads are open, the induced voltage generating from ambient electromagnetic wave can easily be detected by the multimeter when performing mA DC or mV AC measurement, thus, it is normal that the displayed value can not be reset. The displayed value can be reset if the test leads are shorted.
|How to calculate the accuracy error?|
The accuracy is typically denoted in the percentage form of the reading, that is 1% of the reading, for example, if the measured value is 100V, the actual value may be between 99V~101V. But for technical parameters, the least significant digit will be counted into the accuracy, for example, if the accuracy is ±(1%+2) and the measured voltage is 100V, the actual value will lie between 99.8 and 101.2V.
|How to distinguish average response from True-RMS?|
Ture RMS is a representation of non-normal AC signal.
|There is no capacitance display when performing test by UT61E. The symbol of capacitance is displayed when performing test at resistance gear.|
The audion (Q1) at the PCB is broken down. Please send the product to the manufacturer for maintenance.
|RS232/USB cannot connect or communicate with computer.|
1. Check if the USB function is started (There is symbol indication on the LCD)
|No display, display segment missing, or failure to start up.|
Poor contact of conductive adhesive at LCD screen due to impact or bumping. (Apply new conductive adhesive or send the product to the manufacturer for maintenance)
|Is the multimeter protected across all measurement gears? Will the multimeter be damaged if a wrong measurement gear is selected?|
The multimeter is protected by the fuse at current gear, it is also protected at voltage gear as it is able to detect voltage of 1000V and designed with internal resistance of 10MΩ. There is no fuse protecting the multimeter at resistance gear since voltage excitation source exits at resistance gear, the measured resistance is detected by detecting the current flowing through the measured resistance, if the voltage is measured at resistance gear, two voltage sources will crash, which may cause damage to the multimeter at resistance gear. Overload-protection circuit is also designed for the multimeter.
|Large deviation occurs when performing current and resistance measurements.|
The copper wire of the test lead may be broken, please replace the test lead with new one. Note: Do not twist the test leads.
|What is the lowest measured frequency? What is the frequency range when measuring duty cycle?|
Generally, the specification of frequency accuracy is applicable to above 5% or 10% of the range, if below 5% or 10%, the accuracy will be affected, the affected value and the starting value of the range changes upon the models of products. For nonsinusoidal waveform measurement, please select a True-RMS meter and be sure that the range of duty cycle is 1%~99%.
|Why the measured output voltage of frequency converter is inaccurate?|
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 multimeter does not buzz at the buzzing gear or it keeps buzzing at a certain gear.|
The MCU control chip is damaged, please send the multimeter to manufacturer for maintenance.
|Why negative value is displayed when the test leads are shorted at resistance gear?|
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.
|When performing current measurement for power cord through a new clamp meter, why the measured current is zero constantly?|
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.
|Why clamp meter with large range is not suited for measurement of small current?|
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.
|Why the reading can not be reset when performing AC and DC current measurements through clamp meter?|
For AC current measurement:
For DC current measurement:
|Why the displayed measured frequency of AC voltage is unstable at frequency gear?|
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.
|Is peak measurement same with MAX measurement?|
|On the condition that the accuracy is guaranteed, what is the minimum AC current that the clamp meter can measure at current gear?|
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.
|How to start the LPF function? When will this function be used?|
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.
|Why the reading can not be reset for 200M resistance measurement when the test leads are shorted?|
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.
|What is NCV? When NCV will be used?|
NCV refers to Non-Contact Voltage Detection.
|How to use the function of inrush current?|
On the condition that the measured equipment is powered off:
|Why the temperature is still displayed without the temperature probe connected for temperature measurement? Will this affect the temperature accuracy?|
As a temperature compensation circuit is designed inside the meter, the ambient temperature will be displayed without the temperature probe connected.
|The temperature error is relatively large when performing temperature measurement through infrared thermometer. (Measure the temperature of a bottle of boiled water at a distance of 1 meter)|
Please note the points mentioned below when using infrared thermometer:
1. Distance Coefficient Proportion (D:S): This represents the proportion between the distance (from thermometer probe to target) to the diameter of the target. If the target is small and the test distance is long, please select thermometer with high distance coefficient. Note: The range of distance efficient for UNI-T infrared thermometers is between 10:1 to 50:1.
|What if the emission rate is unknown when using the infrared thermometer?|
As we all know, it’s important to adjust the emission rate when using the infrared thermometer, but how can we know the emission rate of the target object? The recognized emission rates of materials including metal and non-metal materials can be searched on line typically, there are two methods for reference if corresponding emission rate is not found out:
1. Apply black adhesive on the measured object to change the emission rate of the target to 0.95.
|Why the dual lasers of infrared thermometer are used?|
Typically, the infrared thermometer makes laser point as an indication of the measured range. The principle of infrared thermometer is the average temperature within the measured circle, if there are multiple temperature points within the circle or the measured circle exceeds the measured object, the measured temperature may be inaccurate, in such case, if infrared thermometer with dual lasers is used, the range of the measured circle can be obtained accurately, to prevent over range of measured temperature, inaccurate temperature, and other issues.
|Why the clam jaw of UT273/UT275 earth clamp tester keeps buzzing when they are powered on?|
Because of the design.
|Can the RCD tester be used to measure three-phase leakage current?|
No, the applicable AC voltage of RCD tester is 195V~253V, the three-phase voltage is 380V.
|Why pure resistance value, absorption ratio and polarization index are required for insulation measurement?|
For insulation test, the insulation resistance at a certain moment can not entirely reflect the insulation performance of tested object, as the insulation resistance absorbs and polarizes electric charges after high voltage is applied on the insulation material. For insulation tests on sites with main transformers, cables, motors and others, absorption ratio (the ratio between R60s and R15s) and polarization index (the ratio between R10min and R1min) should be measured, so as to determine the insulation performance.
|Why the insulation resistance tester is unable to measure the insulation and why 5.5GΩ is displayed always?|
This phenomenon is normal. 5.5GΩ will be displayed when the insulation resistance of measured object exceeds the specified range of the tester, it is recommended to test an object with resitance below 5GΩ.
|The displayed value can not be reset when the circuit of multimeter is open.|
The multimeter has relative measurement mode. Press REL button to enter relative mode. Take capacitance measurement as an example, when REL button is pressed, the displayed capacitance will be reset. To obtain the measured value, the open-circuit value will be subtracted by the displayed value.
|The reading can not be reset at resistance gear when the circuit is open.|
Because the air is moist and the moisture content in the vaseline applied on the PCB pad is increased. Please wipe out the vaseline on the PCB pad and apply new vaseline, or perform measurement when the air is dry.
|Why no voltage is displayed when measuring voltage at a frequency of 1Khz through UT81 series.|
Answer 1: DC and wave form are displayed on the screen, DC indicates the multimeter is in DC mode, and wave form indicates AC voltage measurement. Please press AUTO button to switch to AC mode.
Answer 2: Turn the rotary switch to corresponding measurement gear (AC or DC gear). If the measured signal is not known, please press AUTO button so as to detect the optimum test signal.
|The UT61C multimeter buzzes when switching from voltage gear to mV gear.|
Fault code: 204. Cause: wrong calculation. Solution: operate again as per the user manual.
|Common faults of LM Series Laser Range Finders (LM40 / LM50 / LM60 / LM80 / LM100 / LM120 / LM150)|
1. Fault code: 204. Cause: wrong calculation. Solution: operate again as per the user manual
|Why the clamp jaw with hall component (a clamp meter which can be used to test AC/DC current) keeps buzzing when switching from AC gear to DC gear? Why the reading can not be reset?|
The common cause is that the hall component is damaged, it is recommended to send the product to manufacturer for maintenance.
If the measured voltage is 100V, the actual displayed value will be between 98.8V and 101.2V.
|clamp-meters product-use digital-multimeters|
|What is LPF function?|
Let low-frequency signal pass and stop high-frequency signal from passing. The cut-off frequency point of low pass filter is 1KHz, while VFC is more suitable for measurement of variable frequency. (Note: 40Hz~400Hz). Application case: The detection of inverter and motor drive.
|clamp-meters product-use digital-multimeters|
|What is VFC function?|
It can measure AC voltage and AC current that are interfered by variable frequency.
|Conditions to perform test by UT343D|
FE refers to magnetic-conductive materials such as iron, steel.
|The recording time of UT330A/B/C viewed at the computer can not be updated.|
Open the software after the logger is connected with computer, click “Successful connection”, click “Set dialogue box” to pop up “Device setting box”, click “Synchronize time” to pop up “Successful time setting”. This setting only need to be done for once.
|Why UT513A insulation resistance tester is unable to measure the insulation and why OL is displayed always?|
This phenomenon is normal. OL will be displayed when the insulation resistance of measured object exceeds the specified range of the tester.
Multimeters are indispensable meters in power electronics department, mainly used to measure voltage, current and resistance.
1. 3 1/2 digit multimeters: The maximum display is 1999, and the resolution is 1/2000 of the range;
Distorted waveforms, such as pulse, square, triangle and sawtooth waves, spike pulse and other irregular waveforms.
Equivalent DC value of the AC waveform.
Sine waves without distortion.
|True RMS digital multimeters|
True RMS digital multimeters can accurately measure sinusoidal and non-sinusoidal waveforms.
Auto hold the Max/Min of pulse signals
|ACV LOZ Low impedance|
Low impedance input: False voltage generated by large capacitive equipment can be measured.
AC+DC measurement: Measure signals with AC and DC components (including various waveforms)
|Low-pass filtering/ variable frequency (LPF/VFC)|
LPF/VFC: Filter the influence of high frequency signal on the measurement result
|Relative (REL) mode|
Relative mode: Eliminate low resistance or impedance on the test leads during capacitance measurements
Communication protocols are agreements between communication parties on data transmission control.
1. Install the upper computer software on the computer and connect the original RS232C data cable.
1. Install the upper computer software on the computer.
1. Install the upper computer software on the computer.
1. Install the upper computer software on the computer.
Install the upper computer software on the computer and connect the data cable. Export previous test results to the software (there must be data in the meter). Manually save the data during the test.
|UT612 LCR Meter|
Turn on the meter and connect the USB cable. Short press the USB button, and “S” will show in the upper left corner of the screen. Click Connection on the software.
1. Press the POWER button to turn on the meter.