“Most accurate” power analyser verifies power losses in transformers 

Claimed to achieve the highest possible accuracy at power factors as low as 0.001, the transformer version of Yokogawa’s WT5000 precision power analyser offers 0.008 per cent accuracy.

The WT5000 precision power analyser – transformer version is designed to help transformer manufacturers develop and validate the losses of highly efficient products for utility industry customers.

Transformers are responsible for four per cent of distribution network losses in the power grid, therefore achieving more efficient transformers has never been more important, said Yokogawa. Owners of distribution networks impose penalties on transformer manufacturers according to the degree of losses measured during the no load test. These penalties can exceed €13,000 per kW. Given the measurement uncertainty, it is vital for transformer manufacturers to measure these losses accurately to lower the cost of penalties and build greater trust with customers.

The WT5000 precision power analyser – transformer version helps manufacturers achieve the highly accurate analysis needed to develop economical and efficient transformers. A special input module has much better uncertainty specifications for transformer testing, claimed Yokogawa.

The WT5000 analyser offers accuracy of 0.008 per cent at unity power factor and the best accuracies at low power factors for commercial frequencies of 45 to 66Hz, claimed Yokogawa. Low power factors have a dramatic effect on accuracy, continued the company; the analyser’s accuracy is 0.6 per cent of the reading for measurement, even down to a power factor of 0.001 at 100V and 1A.

The WT5000 precision power analyser – transformer version is supplied with ISO17025 accredited calibration certificates. It is optimised by ISO17025 accredited calibration at 53Hz at power factors of 1, 0.5, 0.05, 0.01 and 0.001. Additional calibration up to 100kHz ensures performance when measuring distorted waveforms, for example during no-load loss current measurements of transformers. This enables the integrated transformer measurement system to measure power losses with great accuracy and capture any drift outside the limits described in the IEC60076-8 Standard, noted Yokogawa. 

The analyser has a full touchscreen supported by hardware hot keys and powerful software for remote data capture. The 10.1-inch WXGA touchscreen delivers noise immunity even in high-noise environments, Yokogawa said. It also allows split screen viewing of up to seven waveforms and can display up to 12 pages of measurement parameters, from products as diverse as inverter-driven motors, renewable energy technologies, and traction applications such as pumps, fans, and electric vehicles and power transformers. Measurements can also be displayed in vector format or trending in time.

Using the WT5000 precision power analyser – transformer version, engineers can measure either three or four different power phases at 10Msamples per second (18 bits). 

Yokogawa offers supporting software packages that can be used to co-ordinate several instruments, including the WT5000, into a single measurement suite to view different data sources simultaneously. 

Some software features allow users to simultaneously view up to 22 waveforms and two harmonic bar graphs (six waveforms, sixteen trends, two vectors, and three harmonic bar graphs: WTViewerE) in split screen mode. Alternatively, they can zoom in using cursors to see more detail in a particular area of interest. Users can customise, save, and load screen layouts as well as specify the data to be saved in CSV format. The software also allows users to create custom computations, combining values from multiple power analysers. 

Up to 32Gbyte of internal storage memory can be used to store and recall various custom configurations and test setups. It can also be used to log large amounts of measurement data over long periods of time, behaving just like a logger. The large non-volatile memory makes it easy to store data without preparing any external media. 

Using the WT5000’s three-phase delta calculation, engineers can check line voltage and phase voltage simultaneously without changing wiring. The built-in delta computation function allows both star-delta and delta-star conversion, allowing users to calculate individual phase voltages from the line voltages measured in a three-phase, three-wire (3V3A) system. 

Harmonic analysis, allowing engineers to evaluate and compare input and output harmonics of inverters, motors, or power conditioners up to the 500th order.  As well as measuring harmonics and power simultaneously, it also offers side-by-side comparison of harmonics from two different input sources. 

http://tmi.yokogawa.com/eu/