22 Jul 2024


New-generation power meter can be used to test motors

Yokogawa has announced the fifth generation of what it claims is the world’s best-selling power meter. The new WT300 meters can measure parameters such as RMS, mean or DC power, frequency, and voltage, as well as harmonics up to the 50th, and display them simultaneously on four readouts. Potential applications for the meters, which can measure currents up to 40A, include motor testing.

Yokogawa already claims to hold 65–75% of the global market for power meters, which are its biggest-selling product. It has sold about 50,000 of the previous-generation WT200 meters since they were launched in 2002. The company hopes that with the new meters it will capture an even bigger share of the market.

The new meters can measure currents from 50µA up to 40A with basic accuracy of 0.1% of the reading, and a guaranteed accuracy over the entire measurement range from 1–130%. As well as measuring DC, the meters can operate from 0.5Hz–100kHz (or up to 20kHz on the 40A version).

Usually, power meters need to switch measurement modes depending on whether they are measuring basic variables (such as voltage, current and power), or more complex items (such as integral power consumption or harmonics analyses) that require calculation. The new meters can measure any of these in a single measurement mode, and operate with a measurement interval of just 100ns.

The meters offer a variety of communications interfaces, allowing them to be integrated into automated test set-ups on production lines. USB and GPIB or RS-232 are standard, with Ethernet available as an option.

Initially, there are four meters in the range with prices from €2,500–7,000. More models will be launched during 2013.

An auto-range function selects the range automatically, thus saving time. Usually, when power meters operate in an integration mode to measure power consumption and standby power, the measuring ranges need to be fixed. However, if the input exceeds the maximum of the selected range, the results will be incorrect and the test will need to be repeated using higher load ranges. The new meters have an automatic range-switching capability that allows one meter to measure both low and high loads continuously. The function is available for Wh, Ah and DC measurements.

The meters can be used for duration testing and efficiency measurements on industrial motors and other rotating machinery. They can provide current integration (Ah) and energy (Wh) measurements for up to 10,000 hours. A digital-to-analogue option can be used to save the data to an external recorder or datalogger, along with other parameters such as temperature, torque values and speed.

Yokogawa offers free software for monitoring power consumption and for testing that equipment complies with energy-saving standards.