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Fluke 438 Power Quality Analyzer & Motor Analyzer

The 438-II Power Quality Analyzer & Motor Analyzer helps you effectively evaluate electrical and mechanical performance just by hooking up voltage and measuring current, providing you with an unprecedented level of data.

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Hard Case 12kg 60L 39W 23H
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The new Fluke 438 power quality analyser and motor analyser adds key mechanical measurement capabilities for electric motors to the advanced Fluke 430 Series II. Now you can quickly and easily measure and analyse key electrical and mechanical performance parameters such as power, harmonics, unbalance, motor speed, torque and mechanical power without the need for mechanical sensors.

A portable motor analysis test tool like the 438-II can help locate, predict, prevent and troubleshoot power quality problems in three-phase and single-phase power distribution systems while giving technicians the mechanical and electrical information they need to effectively evaluate motor performance.

Key Features

  • Measure key parameters on direct-on-line motors and motors driven by specific variable frequency drive systems including torque, RPM, mechanical power and motor efficiency
  • Perform dynamic motor analysis by plotting of motor de-rating factor against load according to NEMA guidelines
  • Calculate mechanical power and efficiency without the need of mechanical sensors, just connect to the input conductors and you’re ready to go
  • Measure electrical power parameters such as voltage, current, power, apparent power, power factor, harmonic distortion and unbalance to identify characteristics that impact motor efficiency
  • Identify power quality issues such as dips, swells, transients, harmonics and unbalance
  • PowerWave data technology captures fast RMS data, and shows half-cycle averages and waveforms to characterize electrical system dynamics (generator start-ups, UPS switching etc.)
  • Waveform capture function captures 100/120 cycles (50/60 Hz) of each detected event, in all modes, without set-up
  • Automatic transient mode captures waveform data at 200 kS/s on all phases simultaneously up to 6 kV.


Drive Measurement Details

Motor Type: 3 phase asynchronous (induction)

Power Source: Variable Frequency Drive

Motor Frequency Range: 40Hz to 70Hz

Over/Under Voltage from Nominal V/f Curve (%): -15% to +15%

Carrier Frequency Range: 2.5kHz – 20kHz


Variable speed drive technology that is covered by the 438-II

Inverter Type: VSI only (voltage controlled)*

Control Method: V/f control, open-loop vector, closed loop vector, drives with encoders

Frequency: 40 to 70 Hz


Variable speed drive technology NOT covered by the 438-II

Inverter Type: CSI (current source inverter)

Motors type: Non-synchronous (DC, stepper, permanent magnet etc.)

Motor Frequency: <40 and >70 Hz


Fluke 438-II mechanical metering functions

Motor torque
Calculates the rotational force (displayed in lb.ft or Nm) developed by a motor and transmitted to a driven mechanical load. The motor torque is the single most critical variable that characterises the instantaneous mechanical performance of rotating equipment driven by electric motors.

Motor speed
Provides the instantaneous motor shaft rotational speed. Combined with the motor torque, motor speed offers a snapshot of the mechanical performance of rotating equipment driven by electric motors.

Motor mechanical load
Measures the actual mechanical power (displayed in hp or kW) produced by motors and provides a direct link to overloading conditions without simply basing it on the motor current.

Motor efficiency
Shows the effectiveness of each motor within a machine, assembly line, plant and/or facility in converting electric power to useful mechanical work. By properly aggregating the efficiencies of a population of motors, the total (aggregate) efficiency can be estimated. Comparisons to expected motor efficiencies at observed operating conditions can help quantify the cost of motor energy inefficiency.

How it works
Using proprietary algorithms, the Fluke 438 power quality analyser and motor analyser uses three-phase current and voltage waveforms to calculate motor torque, speed, load and efficiency at a 1-second update rate. As observed via the voltage/current waveforms, the motor air gap field provides the basis for the measurements. Mechanical sensors and intrusive no-load motor testing are not required, making it faster than ever to analyse overall electric motor performance.

Motor types
The Fluke 438-II can analyse 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.

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

In Motor Analysis mode, results are summarised for electrical performance, mechanical performance and derating (according to NEMA recommendations). The easy-to-understand four-level colour severity scale indicates motor performance concerning the recommended electrical parameters, 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 immediately compared with electrical power to provide live efficiency measurements. This feature allows you to 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 “+”. This example shows that the 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.


  • Industrial motor maintenance — Ideal for routine checks and troubleshooting in industrial settings, the Fluke 438-II helps evaluate motor health and performance. It’s handy for detecting issues in motor efficiency, identifying power quality problems and ensuring motors operate within their optimal parameters, crucial for minimising downtime and maintaining productivity.
  • Energy efficiency audits — By measuring electrical and mechanical power efficiency, this analyser can identify areas where energy usage can be reduced. This is particularly valuable in manufacturing and processing industries where motor-driven systems are prevalent.
  • Commissioning new equipment — During the commissioning phase of motors and drives, the Fluke 438-II provides vital data on motor performance and power quality. This guarantees that new equipment is installed correctly and meets the required operational specifications and standards.
  • Quality control in manufacturing — In manufacturing environments where motor-driven machinery is central, the Fluke 438-II ensures the quality and consistency of electrical supply and motor performance. It’s instrumental in proactive maintenance strategies, helping prevent unscheduled shutdowns and maintaining high-quality production standards.
  • Research and development — Engineers and technicians in R&D can leverage the Fluke 438-II for testing and developing new motor designs or electrical equipment. Its detailed analysis of motor efficiency and power quality provides valuable data for improving designs and innovating more energy-efficient and reliable motor-driven systems.

Secure the Fluke 438 power quality analyser & motor analyser today

Rent the Fluke 438 power quality analyser & motor analyser from Brandis Hire, your reliable partner in technical equipment lease. With 24/7 technical support, flexible hire periods and hassle-free nationwide shipping, we make equipment hire easy and stress-free. As a 100% Australian, family-owned business, we deliver industry-leading customer service. Submit a booking request, or contact us for personalised assistance.​


Why choose the Fluke 438 power quality analyser & motor analyser?

Choosing the Fluke 438 is a wise choice for professionals needing comprehensive electrical and mechanical performance analysis. This advanced tool offers unparalleled insights into motor health, efficiency, power quality and energy usage. It can measure key parameters such as torque, RPM and motor efficiency, making it ideal for industrial maintenance, energy audits, equipment commissioning and research. Its user-friendly design, robust construction and battery-powered portability make it suitable for diverse environments. This versatile analyser ensures precise diagnostics, helping you maintain optimal performance and prevent costly downtime.

What other power quality analysers do you offer for hire?

When it comes to ensuring the quality of your power systems, having the right equipment is crucial. In addition to the Fluke 438, we offer a range of power quality analysers to suit different requirements and applications. Here are some other options available for hire:

How does the Fluke 438 ensure accuracy in motor analysis?

The Fluke 438 employs advanced algorithms and precise electrical measurements to calculate mechanical parameters like power, torque and efficiency to ensure high accuracy in motor analysis. This level of precision is critical for reliable diagnostics and effective maintenance strategies, especially in demanding industrial environments.

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Fluke 438 Power Quality Analyzer & Motor Analyzer