Yokogawa claims industry’s highest accuracy for power analyser

Technology News |
By Nick Flaherty

The higher accuracy of the WT5000 comes from the optimisation of margins across the different modules which are self contained, says Anoop Gangadharan, the Product Marketing Manager for Power Measurement Solutions at Yokogawa Europe. The power dissipation from each of the modules across the chassis is also optimised to ensure that the modules stay within specification to maintain the accuracy.

The analyser uses an 18bit analgoue to digital converter (ADC) with a sampling frequency of maximum 10 MS/s. As a result, it becomes possible to accurately capture waveforms from the latest high-speed inverters used in electric vehicles and renewable energy systems.

The high level of accuracy at 50/60 Hz and wide dynamic current range enables more effective evauation of the efficiency of the system under test where a difference of 0.1% matters.

The WT5000 has the same dimensions as existing models in Yokogawa’s WT series and handles up to seven input channels, allowing it to support applications that previously could only have been measured by synchronising several separate instruments.

The plug-in modular input elements can be swapped directly by the user. The 30 A and 5 A elements, for example, can be switched for applications involving electric vehicles or fuel-cell vehicles, where developers are increasingly required to evaluate a number of different motors. Using the WT5000 equipped with the /MTR1 and /MTR2 options, it is possible to evaluate up to four motors simultaneously with one unit. Since these options allow the input of four channels, flexible measurement of the A, B, C and Z phases of each motor can be carried out.

Next: Mesuring harmonics

With a 7 elements input capability, multi-system measurement is increased in harmonic measurements on 3-phase systems, for example. The WT5000 can carry out two harmonic measurement functions simultaneously, each at up the 500th order and up to 300kHz fundamental waveform. This makes it possible to measure the carrier frequency component from the rotational speed of the motor in the inverter drive and also to check the influence of the carrier frequency on the motor drive.

An increasing number of applications require the evaluation of larger-current devices, typical examples being electric vehicles and large-scale solar installations. In these cases, external current sensors are often used.  An external current sensor input function is fitted as standard in the input element of both the 30 A and 5 A input elements of the WT5000. For much higher currents (up to 2000 A RMS) dedicated high-current sensors are available. Yokogawa AC/DC current sensor CT series is current output type in order to prevent noise influence.

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