eFocus Instruments India Pvt Ltd

Porur, Chennai, Tamil Nadu

The new Fluke 438-II Power Quality and Motor Analyzer adds key mechanical measurement capabilities for electric motors to the advanced power quality analysis functions of the Fluke 430 Series II Power Quality Analyzers. Quickly and easily measure and analyze key electrical and mechanical performance parameters such as power, harmonics, unbalance, motor speed, torque and mechanical power without the need of mechanical sensors. Fluke 434-II, 435-II and 437-II Power Quality Analyzer users can add motor analysis capabilities to their existing units with the Fluke-438-II/MA Motor Analyzer upgrade kit.

Using proprietary algorithms, the Fluke 438-II Power Quality and Motor Analyzer uses three-phase current and voltage waveforms to calculate motor torque, speed, load and efficiency at a 1 second update rate. The motor air gap field, as observed via the voltage/current waveforms, provides the basis for the measurements. Mechanical sensors and intrusive no-load motor testing are not required, making it faster than ever to analyze overall electric motor performance.

The Fluke 438-II can analyze both direct-on-line motors and motors powered by variable frequency drive (VFD) systems. The VFD must be a voltage controlled system (VSI) with a voltage / frequency range of 40 to 70Hz, and a carrier range of 2.5kHz to 20kHz.

The Fluke 438-II provides a complete breakdown of electrical parameters. Prior to beginning motor analysis, it's recommended to make base line power quality measurements to assess the state of harmonics and unbalance on the electrical service output as these two properties can have a serious negative impact, on motor performance.

When in Motor Analysis mode, results are summarized for electrical performance, mechanical performance and derating (according to NEMA recommendations).

The easy to understand four-level color severity scale indicates motor performance in relation to the recommended electrical parameter levels including rated power, power factor, unbalance and harmonics.

For mechanical power you can instantly view the mechanical output power along with motor torque and speed. The mechanical output power is instantly compared with electrical power to provide you with live efficiency measurements. With this feature you can easily measure machine performance during each operation cycle.

The NEMA derating screen is updated as the load and the electrical conditions change, and each new measurement is plotted on the tolerance graph as a "+". In this example we can see that motor is within tolerance but is close to the service factor. This indicates that there may be a need for power quality mitigation, motor maintenance or some other performance improving adjustment. By frequently performing these tests over time, known benchmarks and performance trends can be created, enabling informed maintenance investment decisions.