Q96-WTCAN Q96-WTCZAN Q96-WTCA-NA Q96-WTCZA-NA Reverse power meter

Q96-WTCAN Q96-WTCZAN Q96-WTCA-NA Q96-WTCZA-NA Reverse power meter

Q96-WTCAN Q96-WTCZAN Q96-WTCA-NA Q96-WTCZA-NA Reverse power meter can directly replace conventional power transmitter and measuring instrument. As an advanced intelligent and digital front-end acquisition element, the power instrument has been widely used in various control systems, SCADA systems and energy management systems. The instrument adopts AC sampling technology, which can measure the power parameters in the power grid. It can set the magnification through the panel membrane switch, with RS485 communication, alarm output, switching value input / output and other functions.

Power is an important parameter to characterize the characteristics of electrical signals. In the DC and low-frequency range, power can be calculated by measuring voltage and current. The instantaneous value of power can be expressed by the following formula:

For periodic signals, the average value of instantaneous power in a period is called active power. The active power is calculated according to the following formula:

For sinusoidal circuits, the following formula holds:

In the above formula, u and I are the effective values of sinusoidal AC respectively, φ Is the phase difference between voltage and current signals.

In UHF and microwave bands, there are TEM waves and non TEM waves. In the coaxial system of TEM wave, although the voltage and current have definite meaning, it is difficult to measure their absolute values. In waveguide system, voltage and current lose uniqueness because of different electromagnetic modes. In each frequency band and transmission system, power is an important method for single value to characterize signal strength. The direct measurement of power in the RF range replaces the measurement of voltage and current.

Unit of measure edit broadcast

Q96-WTCAN Q96-WTCZAN Q96-WTCA-NA Q96-WTCZA-NA Reverse power meter is defined as the work done per unit time. The basic unit is watt (W). 1W is equal to doing 1 joule of work in 1 second. Common power units include megawatt (1MW = 10 ^ 6W), kilowatt (1kW = 10 ^ 3W), milliwatt (1MW = 10-3w) and micro watt (1 μ W = 10-6w), Piwa (1pw = 10-12w).

Another common unit of power is expressed in decibels and milliwatts (DBM). It takes 1MW as the reference level, P0 = 1MW, and the actual power value p (MW) is logarithmic after comparison with P0. This is the absolute unit of power.

Decibel watt (DBW) can also be used as the power unit. At this time, P0 = 1W, that is, 1 DBW = 3 DBM.

Classification standard editing and broadcasting

Figure 1 common frequency conversion electric quantity waveform and spectrum

Figure 1 common frequency conversion electric quantity waveform and spectrum (5 sheets)

Classify according to the frequency of the measured signal

Power meters can be divided into: DC power meter, power frequency power meter, frequency conversion power meter, RF power meter and microwave power meter. Because the DC power is equal to the simple product of voltage and current, voltmeter and ammeter are generally used in actual measurement. Power frequency power meter is a widely used power meter. The commonly used power meter generally refers to power frequency power meter. Variable frequency power meter is the product of the rapid development of variable frequency speed regulation technology in the 21st century. The measurement object is variable frequency power, which refers to the AC power used to transmit power and meets one of the following conditions:

1. The signal spectrum contains only one frequency component, and the frequency is not limited to the AC signal of power frequency.

2. An electrical signal whose spectrum contains two or more frequency components of interest.

Variable frequency electric quantity includes voltage, current and active power, reactive power, apparent power, active electric energy, reactive electric energy, etc.

In addition to the PWM wave output by the frequency converter, the current waveform input by the frequency converter rectified by the diode, the voltage waveform output by the DC chopper, the input current waveform of the no-load transformer, etc., all contain large harmonics, as shown in Figure 1 for the waveform and related spectrum diagram of common frequency conversion electricity.

Due to the complex frequency component of variable frequency power, the measurement of variable frequency power meter generally includes fundamental active power (hereinafter referred to as fundamental power), harmonic active power (hereinafter referred to as harmonic power), total active power, etc. compared with power frequency power meter, it has more functions and more complex technology. It is generally called variable frequency power analyzer or broadband power analyzer. Some high-precision power analyzers are also suitable for variable frequency power measurement.

The frequency conversion power analyzer can be used as a power frequency power analyzer. In addition, it generally needs to meet the following requirements:

1. Meet the necessary bandwidth requirements, and the sampling frequency shall be higher than twice the instrument bandwidth.

2. The analyzer is required to be in a wide frequency range and the accuracy can meet certain requirements.

3. It has the function of Fourier transform, which can separate the fundamental wave and harmonic of the signal.

RF or microwave power meters are classified according to the connection mode in the test system

There are terminal type and through type. The terminal power meter takes the probe of the power meter as the terminal load of the test system. The power meter absorbs all the power to be measured, and the power value is directly read by the power indicator. The through type power meter uses some coupling devices, such as directional coupler, coupling ring, probe, etc., to couple part of the power from the transmitted power in a certain proportion and send it to the power meter for measurement. The total transmitted power is equal to the indicated value of the power meter multiplied by the proportion coefficient.

RF or microwave power meters are classified according to their measurement principles

Thermal resistance type power meter uses thermal variable resistance as power sensing element. The temperature coefficient of thermal resistance value is large. After the power of the measured signal is absorbed by the thermal variable resistance, heat is generated to raise its own temperature and the resistance value changes significantly. The resistance bridge is used to measure the change of the resistance value and display the power value.

Thermocouple type power meter the thermocouple junction in the thermocouple type power meter directly absorbs the high-frequency signal power, and the node temperature rises to produce the thermoelectric potential. The magnitude of the potential is directly proportional to the absorbed high-frequency power value.

Calorimetric power meter is a typical thermal effect power meter, which uses the heat insulation load to absorb the high-frequency signal power to increase the temperature of the load, then uses the thermocouple element to measure the temperature change of the load, and calculates the high-frequency power value according to the generated heat.

Crystal detector power meter crystal diode detector converts high-frequency signal into low-frequency or DC electrical signal. Properly select the working point so that the amplitude of the detector output signal is directly proportional to the power of the high-frequency signal.

RF or microwave power meters are classified according to the continuity of the measured signal

There are continuous wave power meter and pulse peak power meter.