Power meets precision

The PX8000 brings oscilloscope-style time-based measurement to the world of power measurement. It can capture voltage and current waveforms precisely, opening up applications for a huge variety of emerging power measurement problems. Uniquely, the instrument can undertake instantaneous power measurements, true waveform analysis and conduct simultaneous harmonic measurements.

"With the launch of the PX8000, R&D professionals need no longer compromise on their need for high-accuracy time-based power measurement: a need that conventional power analysers and oscilloscopes were never designed to meet, ” says Terry Marrinan, Yokogawa’s vice president, Test & Measurement, for Europe & Africa.

Applications for the PX8000 cover everything from sustainable power to advanced robotics. Any situation where power consumption is at a premium – which means almost anywhere power is consumed – can benefit from the introduction of the PX8000’s precision measurement and analysis capabilities.

The new instrument has 12-bit resolution with 100MS/s sampling and 20MHz bandwidth. This means that the PX8000 can be used for accurate measurement of inverter pulse shapes, which can then be used to fine-tune inverter efficiency. A choice of input modules covers voltage, current and sensor measurements at voltages up to 1000V RMS and currents up to 5A RMS (higher values are possible with external current sensors), with basic accuracy down to +/-0.1%.

To evaluate three-phase electrical systems, at least three power measurement inputs are required. The PX8000 not only has four inputs but also enables the simultaneous capture and display of voltage and current across all three phases.

The PX8000 comes with an accompanying PC software application called PowerViewerPlus that can be used to capture waveform data for further analysis. This dramatically extends the number of data points it is possible to analyse, making the PX8000 ideal for capturing and analysing longer-term performance. PC connection is via standard Ethernet/USB/GP-IB connections. The user-friendly software displays waveforms in a simple and clear graphical style that will be familiar to users of Yokogawa’s popular Xviewer software. Researchers who want to use their own analysis software will be able to establish a connection to the PX8000 via the LabVIEW driver.

The capability comes at a price, however: EUR12,500. Understanding the needs of an application is key to deciding whether or not this investment, significantly above that of a conventional power measurement instrument, is justified. Here are some promising examples:

Transient responses of industrial robots

To evaluate motor-driven robots, power consumption of all motors and controllers are measured throughout all operational speeds and action patterns. Design engineers need to measure inrush voltage, current and power over the pattern of repeated actions. Efficiency is calculated by comparing mechanical output with input power.

During actual operating conditions, the time to accelerate and decelerate such motors can range from several hundred milliseconds to several seconds. As a PWM-driven motor rotates from the reset position to the top speed, the drive frequency changes from DC to several hundred Hz. The PX8000 gives design engineers insight into power consumption and efficiency throughout a robot’s operational performance.

Reactor loss measurement of inverter boost circuits

A reactor is used to filter out noise and boost voltage levels prior to the use of an inverter. It consists of an electromagnetic material core and a coil. A main focus for electrical engineers is to reduce power loss across the total inverter system, and reactor performance is of particular interest. There are two potential evaluation methods: direct loss measurement of the reactor; and iron loss measurement.

The PX8000 supports either methodology because it can accommodate both high frequency measurement and low-power-factor conditions.