23 Jul 2024


‘Most accurate’ power meter can analyse four motors at a time

Users can add or remove up to seven modules to tailor the instrument to their needs

Yokogawa has developed what it claims is the world’s most accurate power analyser for evaluating the power consumption, loss and efficiency of electrical and electronic devices, including inverters. The WT5000 analyser boasts an accuracy of ±0.03% (±0.01% of reading and ±0.02% of range) at 44–66Hz, and can be extended using plug-in input modules to evaluate up to four electric motors simultaneously – an ability that is expected to appeal to developers of electric vehicles, among others.

To achieve its accuracy, the instrument uses an 18-bit analogue-to-digital converter with a sampling frequency of up to 10 megasamples per second. This allows it to handle the higher switching frequencies being used as semiconductor technologies evolve, and to capture waveforms accurately from the latest high-speed inverters, for example. The analyser operates over a frequency range from DC to 5MHz.

It can accommodate up to seven input channels, allowing it to handle applications that could previously be measured only by synchronising several different instruments. This capability also saves space and communications overheads. 

The plug-in input modules, which can be swapped by the user, include 5A and 30A versions with external current sensor input functions. High-current sensors are available for currents up to 2kA rms. Yokogawa’s AC/DC current sensors output currents to avoid noise effects.

The WT5000 can carry out two harmonic measurement functions simultaneously at up to the 500th order, and with fundamental waveforms up to 300kHz. This means that it can measure the carrier frequency component from the rotational speed of a motor in an inverter drive, and check the influence of the carrier frequency on the drive.

When being used to analyse motors, the instrument can measure A, B, C and Z phases. It accepts inputs from torque sensors and rotary encoders to determine parameters such as rotational speed, direction, mechanical power, synchronous speed, slip, electrical angles and efficiency.

The instrument’s 10.1-inch colour touchscreen display can be used to compare waveforms, examine trends and analyse harmonics. Measurements can be compared using a split-screen mode.

Anoop Gangadharan, Yokogawa’s product marketing manager for power measurement systems in Europe, believes that the WT5000 will set a new benchmark for instruments of this type: “It’s not just a power analyser, it’s an extensive platform,” he says.