During frequency measurement, a resolution of 1 mHz can be achieved for an input at the commercial line frequency. Peak hold function By using this function, you can hold and display the maximum value peak value of each measurement value. This does not apply to integration or harmonic analysis. Key-lock function This function enables you to disable the keys so that settings are not changed if you accidentally touch the keys during measurement.
Current inputs Large capacity diodes are installed to protect the internal shunt resistors from damage in the event of an input overload. The current inputs are isolated from the voltage inputs.
The maximum withstanding voltage between the voltage and current input terminals is V AC. You can freely select the items to be output on these 14 channels as well as the communication output and printer output. New high-speed-response type digital filter For the WT series, we installed a high performance DSP and also developed a "variable attenuation type filter method" as same as to realize multiple items simultaneous measurement and high speed response which are required for electric power measurement.
Superior noise immunity PWM type inverter equipment which is very widely used generates a voltage waveform by switching the frequency conversion circuit, hence the output contains a lot of noise. Integration function; High speed sampling that enables the instrument The integration method used in the WT series enables the instrument to continuously acquire data by sampling the input signal at a high rate of about kHz.
An example of frequency vs. Application Note. High Current Measurement Application Note. Overview: Designing an instrumentation system for high current measurement requires careful consideration of the trade-offs associated with each type of sensing device.
White Paper. Overview: The objective of this paper is to show the close relationship between efficiency and power quality, and provide education on the causes of power quality, types of power quality issues, and provide guidance on measurement considerations.
Overview: Check for differences in the specifications or features of the instruments. Overview: In the case of three-phase three-wire, or 3V3A wiring, the power, power factor, and phase angle of each input element do not match because it is the line to line voltage that is measured.
Please download and refer Check the sync source setting. For example, route the input to a three-phase device under measurement to input elements on the power meter, Overview: The waveform may actually not be a pure sine wave. Overview: Check the "Sync Source" and zero cross filter frequency filter settings.
For the WT, "Sync Source" setting is irrelevant if the data update rate is ms, ms, 1 s, or 2 s. Sync Source SettingIn principle, if Overview: In the three-phase three-wire, or 3V3A wiring scheme, the phase angle of voltage and current input to each input differs from that of the actual load because it is the line to line voltage that is measured. Overview: The peak value and crest factor may be unstable if they have not been captured accurately.
If the peak value is not stable, neither will the crest factor be stable. The cause is the difficulty in capturing the narrow Overview: The input terminals on all Yokogawa power meteras are located on the rear panel.
This takes into account safety when handling the measuring instrument. The signal input to the power meter normally carries high Overview: This is to prevent an open current circuit. Among non-Japanese power meters, there are products that also use safety terminals for current terminals.
Safety terminals can be said to be safe because the terminal is not The input resistance of the voltage-input circuit is 2. This configuration is employed in order to keep the voltage applied to each of these resistors low so that less expensive resistors can be used with this circuit.
This configuration is employed in order to reduce the effects of a magnetic field formed by a large, high-frequency current, thus providing excellent frequency and phase characteristics. Figures 3 and 4 show the power vs. Data converted to digital values at the input section undergo a corrective calculation against input-circuit errors, and the calculations of active power and the rms values of voltage and current, and then the calculations of apparent and reactive powers, power factor, and so on, at the DSP section.
The following are the formulas for these calculations:. The active power and rms values are calculated using data sampled over an integral multiple of the period of the input signal. This interval is determined by the zero-cross signal derived from the input signal.
If the input signal frequency becomes more than half as high as the sampling frequency, the period of the input signal fails to match that of the waveform reproduced after sampling, resulting in an error in the measured value. The interval over which calculations are performed is thus determined from the period of this zero-cross signal. Figure 5 shows the measuring principle represented by the time relationships. Traditionally, power consumption, torque and rotational speed have been measured separately in the characterization testing of motors.
In this method, the time at which torque and rotational speed were measured was not consistent with that at which power was measured, requiring adjustments between these times. The motor-characterizing capability of the new WTM digital power meter measures both power and torque almost simultaneously if the torquemeter's response is fast enough, compared with ms, eliminating the need for such adjustments. The power meter can calculate the output of motors from the torque and rotational speed to figure out the efficiency between the input and output of a motor, or the efficiency between the inputs and outputs of an inverter and its inverter- driven motor system in the case of a single-phase input inverter.
The meter can also calculate synchronous speed and slippage, enabling users to obtain all required data only from their power meter. Using the motor-characterizing capability, users can test motors with ease to characterize them.
Figure 6 is an example of the WTM digital power meter wired for its motor- characterizing capability. Along with an increasing concern over harmonic current measurements, the latest sampling power meters have been provided with a harmonics-analyzing capability. The WT series discussed in this paper also has this capability. The harmonics-analyzing capability of these power meters can measure not only the conventional harmonics components, harmonics content and distortion factor but also phase angles formed between elements, as well as the apparent and reactive powers and the power factor of a fundamental wave which are difficult to measure in normal measurement.
The measurable range of fundamental frequencies has been extended to a low of 10 Hz, compared with the conventional limit of 40 Hz. This improvement has made it possible to use these power meters not only in harmonics current measurements of commercial power sources but also in other areas of application. Technical Support. Instruction Manuals.
Application Notes White Papers. Application Note. High Current Measurement Application Note.
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