IN Brief:
- The WT1500 provides total power accuracy of ±0.038% at DC and mains frequency.
- Separate elements support direct 2,000V DC measurement or bandwidth extending to 2MHz.
- Resolver, encoder, CAN FD, timing, and multi-unit functions address increasingly complex converter and motor systems.
Yokogawa Test & Measurement has introduced the WT1500 precision power analyser for high-voltage energy storage, power conversion, renewable-energy equipment, electric drivetrains, and semiconductor test systems.
Direct measurement extends to 2,000V DC without an external high-voltage divider, while total power accuracy is specified at ±0.038% for DC and 50/60Hz measurements. Low-power-factor accuracy reaches ±0.07% of apparent power at mains frequency, supporting measurements in which phase error can dominate the uncertainty.
Two input-element types allow the instrument to be configured around different voltage and bandwidth requirements. The high-voltage element supports direct 2,000V DC operation with bandwidth to 300kHz, whereas the wideband element handles up to 1,000V with 2MHz bandwidth for inverter and motor waveforms containing fast switching transitions.
Within a 2U chassis, one instrument can perform up to four power measurements and four motor evaluations. Encoder and resolver inputs bring electrical power and shaft-position data into the same acquisition environment, avoiding the need to align separately recorded datasets after a test.
Communications functions include IEEE 1588 time synchronisation, CAN and CAN FD output, and low-latency transmission through UDP. Planned support for synchronising five instruments will create a 20-channel system controlled from one main unit, while current-sensor interfaces and adapters cover measurements extending into the kiloampere range.
Wide-bandgap switching raises measurement demands
Higher DC-bus voltages are spreading across vehicle drivetrains, storage systems, renewable converters, charging infrastructure, and data-centre power equipment. Increasing the voltage reduces current for a given power level and can allow smaller conductors, although insulation, clearance, protection, connector, and measurement requirements become more demanding.
External dividers extend an instrument’s voltage range but add ratio error, phase shift, temperature drift, cabling, and another calibration chain. Those effects become significant when efficiency improvements are measured in fractions of a percentage point, particularly across several conversion stages whose individual losses must be separated.
Bandwidth introduces a different source of uncertainty because silicon-carbide and gallium-nitride switches produce faster voltage and current transitions than conventional silicon devices. Measuring only the fundamental electrical frequency omits switching behaviour that contributes to power loss, electromagnetic emissions, insulation stress, and common-mode current.
Capturing a wider spectrum requires probes, current sensors, cabling, channel alignment, and sampling performance capable of preserving the waveform. A high nominal instrument bandwidth cannot compensate for a current transducer with limited response or for propagation delay between the voltage and current channels.
Phase alignment becomes especially important at low power factor and high frequency, where a small timing error can produce a large error in calculated power. Calibration and deskew therefore remain necessary even when the analyser’s internal accuracy is high, and uncertainty must be considered across the complete measurement chain.
Integrated high-voltage measurement is also moving onto production electronics, with Texas Instruments combining a 1,200V measurement signal chain within an embedded design. Laboratory analysers provide the reference against which those on-board circuits can be calibrated and verified before they are relied upon for protection, energy accounting, or condition monitoring.
Motor systems add mechanical position and speed to the electrical measurements, requiring resolver or encoder information to remain aligned with voltage and current. Acquiring those signals together reduces post-processing and prevents independent clocks from drifting during lengthy drive-cycle or endurance tests.
Synchronised multi-unit operation supports systems containing several converters, motors, storage interfaces, or three-phase paths. An electric axle may combine an inverter, motor, DC link, auxiliary supply, and mechanical output, while a storage system can contain several conversion stages whose losses must be measured under the same operating event.
The WT1500 is scheduled for release on 19 August, with its direct high-voltage input and scalable channel architecture reflecting the shift from individual converter measurements towards integrated energy-system analysis. Current sensing, wiring, calibration, and test procedure will continue to define the final uncertainty, but removing external voltage dividers reduces one source of error from an increasingly demanding measurement chain.
