TRANSMISSION & DISTRIBUTION
PRECISION POWER ANALYSIS
How a loss measuring system is ensuring that transmission companies can accurately review the amount of energy reaching their consumers
T
ransformers are a crucial part of electricity distribution and transmission networks, performing the important
conversion steps between the very high voltage at which power is transmitted over long distances to intermediate voltages in local networks or lower voltages to households and commercial users. Achieving this with minimal losses
is a high priority for electricity distribution and transmission network operators, who only earn revenues on the power that is actually supplied to their end users. Electrical equipment supplier Royal
SMIT Transformers B.V. supplies large, high-voltage transformers to energy generation and energy transmission companies all over the world. It is responsible for phase-shift transformers and shunt reactors as well as developing, producing, selling and maintaining transformers rated from around 200 MVA up to 1,200 MVA in a voltage range up to 765 kV. Every customer requirement is
unique, and nearly every transformer is custom engineered to order. Being able to measure power losses accurately to make sure products comply with specifications is an important part of the process. Each of Royal SMIT’s test bays incorporates a three-phase transformer power-loss measuring system consisting of high-voltage reference capacitors, zero-flux current transformers, and a three-phase precision power analyser supplied by Yokogawa Test and Measurement. When Royal SMIT decided to build
a new test facility, the challenge was to design a stable and reliable environment in which measurement uncertainty forms a negligible component of measured losses. Part of the solution, based on experience with Yokogawa precision power analysers that have served Royal SMIT well in
10
www.engineerlive.com
The -WT5000 Precision Power Analyser – Transformer Version
the past, was to use Yokogawa’s newer WT5000 model. The WT5000 Transformer Version’s
accuracy of just ±0.008% at a power factor of one restricts measurement error to a negligible fraction of total measured losses. It also achieves the highest possible accuracy at power factors as low as 0.001. One feature that contributes to the
WT5000’s accuracy and long-term stability is a special aging treatment. First the instrument is optimised by calibration at 53 Hz at power factors of 1, 0.5, 0.05, 0.01 and 0.001. Additional calibration at up to 100 kHz ensures the required performance when measuring distorted waveforms that can be encountered when measuring no-load loss currents. Other features include an intuitive
user interface with the ability to define and use event triggers and custom computations. The WT5000 Transformer Version
has helped Royal SMIT reduce measurement error significantly, with 12-month accuracy improved from ±0.01% to ±0.008%. The linearity of the WT5000 Transformer Version is also impressive, according to the company The newer product offers one effective input range covering values from 10% to 110%, as well as sampling 50 times faster than the WT3000 and providing resolution that is four times higher. According to Steven Lauf, senior test
engineer at Royal SMIT, the WT5000 has operated “completely trouble free, and the three measurement channels being operated in the test system hardly need to be adjusted at all, even though the instrument can be on for days at a time.”
For more information visit:
www.yokogawa.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56
