• Glossary

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.

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.

Multimeters are indispensable meters in power electronics department, mainly used to measure voltage, current and resistance.
They can be used to measure resistance, AC/DC voltage, AC/DC current, parameters of transistors, capacitance of capacitors, inductive value of inductors, voltage frequency, duty cycle and temperature.

1. 3 1/2 digit multimeters: The maximum display is 1999, and the resolution is 1/2000 of the range;
2. 4 1/2 digit multimeters: The maximum display is 19999, and the resolution is 1/20000 of the range;
3. 5 1/2 digit multimeters: The maximum display is 199999, and the resolution is 1/200000 of the range;
In addition: The first displays of some digital multimeters are 1, 3, 4 and 5, and their maximum displays are 19999、39999、49999、59999. They are known as 4 1/2 digit, 4 2/3 digit, 4 3/4 digit, 4 4/5 digit and 4 5/6 digit multimeters.

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 can accurately measure sinusoidal and non-sinusoidal waveforms.
True RMS: Effective expression of abnormal AC signals
Ordinary multimeters measure RMS indirectly by measuring the average or peak. True RMS multimeters can real-time measure the RMS of various voltage waveforms without considering waveform parameters and distortion.
To obtain accurate measurements for pulse, distortion, frequency conversion, square wave and other non-sinusoidal signals, a true RMS digital multimeter is an ideal choice.

Auto hold the Max/Min of pulse signals
Uni-Trend’s multimeters with peak hold function record the peak Min/Max with the minimum response time of 250us. With this function, users can observe the peak voltage and current generated when the meter is turned on to avoid device damage.

Low impedance input: False voltage generated by large capacitive equipment can be measured.
The input impedance of a low-impedance multimeter is 300kΩ. It can discharge the residual voltage and determine whether the residual voltage exists.
The input impedance of an ordinary multimeter is as high as 10MΩ. Therefore, residual voltage cannot be identified, resulting in misjudgment or security risks.
There will be residual voltage after powering off large capacitive equipment.
Applied to all electrical equipment, such as reactive power compensation cabinets, large commercial fluorescent lamps.

AC+DC measurement: Measure signals with AC and DC components (including various waveforms)
Ordinary multimeters can only measure pure AC/DC signals. If the measured AC signal is mixed with the DC signal, the AC signal reading is meaningless. For Uni-Trend’s multimeters with AC+DC function, the AC and DC components are measured together.
Importance of AC+DC signals: Reduce equipment failure caused by DC underamplitude. High frequency interference of AC can be observed during DC measurement.
Examples: Railway-transformation central control system, Power-photovoltaic inverter control cabinet, Medical-spiral CT

LPF/VFC: Filter the influence of high frequency signal on the measurement result
The built-in low-pass filters of multimeters with low-pass filtering function will intercept signals higher than 1KHz and weaken signals lower than 1KHz and higher than 100Hz, and can measure the fundamental wave signals of frequency converters or inverters.
A low-pass filter is a circuit that allows low frequency signals to pass and weakens high frequency signals.
Low-pass filtering takes 1KHz as the cutoff frequency point, and VFC is more suitable for frequency conversion measurement. (Note: 40HZ-400Hz)