E-Lub Tester

E-Lub Tester for Four-Ball Tester

Dielectric test rig for lubricant impedance and breakdown measurement in bearings by use of the four-ball tester

The E-Lub Tester determines the ohmic resistance and capacitance of a test bearing and of the lubricant used therein under real operating conditions applied by the four-ball tester.

For this, a high-precision impedance measurement is used, which was developed based on flucon's EPSILON+ laboratory instrument.

In addition, the E-Lub Tester will analyze "EDM" breakdown currents and the dielectrical strength under a defined electrical load that is applied directly to the test bearing, so that the performance and discharge tendency of oils and greases can be investigated under fully variable operating conditions (lubricant temperature, speed, load).


Key features

  • measurement of the lubricant impedance in a test ball bearing
  • test cell for axial ball bearings (standard: type 51208), optionally radial ball bearings (type 6008) or roller bearings
  • determination of ohmic resistance and capacitance
  • EDM breakdown analysis (short-circuit Scan): measurement of electrical discharges and ohmic currents during operation, full statistical analysis
  • variable operating parameters: via E-Lub Tester: lubricant temperature (automatic control), electrical load (common-mode voltage); via FBT: running time, speed, load (all stored in the program)
  • automated and semi-automated test campaigns
  • includes intuitive software for control and measurement with a Windows PC
  • includes impedance calibrator


E-Lub Tester for Four-Ball Tester

Main components

The E-Lub Tester consists of two main components: the FBT adapter serves as the test cell, which contains the thrust ball test bearing as well as the impedance and temperature sensors. When inserted into the four-ball tester, it replaces the traditional four-ball setup.


The control cabinet complements the composition. It holds the impedance meter and the signal generator as well as additional electronics for precise application of the electrical load and for the analysis of the breakdown tendency.

A fluid circulator is used as a thermostat and can be connected to the FBT adapter for automated temperature control of the bearing and its lubricant.

With the included PC software each test can be carried out automatically within a desired temperature range.

Background: breakdown currents in the lubrication gap

With the electrification making bigger progress every day, the electrical and dielectric properties of oils and greases are becoming more and more important. Lubricants used in anti-friction bearings must have a certain specific conductivity so that static charges and resulting electrical breakdowns can be minimized to prevent damage to both bearings and lubricants.

The investigations of bearing-based spark erosion or "Electric Discharge Machining" (EDM) effects are relatively new. It is now known, however, that in addition to friction, electric breakdowns also occur in rolling bearings as a common phenomenon that causes considerable damage to the bearing shells: sudden discharges with high currents lead to pitting damage, i.e. crater and corrugation formations in the running surfaces.

Also, the lubricant in the bearing ages excessively when the breakdown voltage is reached: local overtemperatures in the lubrication film cause permanent damage to greases and oils so that the lubrication is severely affected.

EDM current in roller bearing - E-Lub Tester for Four-Ball Tester
Bearing and lubricant damage through EDM

A new dynamic method: Impedance measurement on lubricated bearings under real-life conditions - with laboratory-like accuracies

With flucon's E-Lub Tester it is now possible to determine the lubricant impedance and breakdown tendency directly in the bearing, under real process conditions. The proven technology of the EPSILON+ Dielectricity Meter is used for highly accurate measurement.

Intuitive software for guided or automated testing

Both impedance measurement and EDM breakdown analysis of your lubricant are carried out automatically, thanks to the included software for your Windows PC. Here, various standardized and custom test modes are available.

E-Lub Tester software (included)

Fields of application

The characteristic data generated with the E-Lub Tester can be used in lubricant development as well as for the following exemplary applications, where electric discharges play an important role:

  • electric motors with variable speed
  • e-mobility
  • gear technology
  • railway technology
  • wind turbines

Available now: In-house demo and service testing

On request, we can carry out measurements for you using our in-house equipment. This is, of course, possible according to the draft standard or also with individual boundary conditions suitable for you (with variable filling quantity, temperature, speed, load, applied voltage signal, running time).

Simply send in your lubricant sample and receive an extensive test report within a few work days.

Any questions about the test services by means of our E-Lub Tester? Please do not hesitate to contact us!

E-Lub Tester software (included)

Technical specifications - E-Lub Tester

Determined data ohmic resistance, capacitance, breakdown frequency (number & amplitude of EDM currents)
Compatible substances Greases and oils
Bearing types 51208 (coming soon: 6008)
Material - FBT adapter stainless steel with PEEK housing and assembly handle
Temperature measurement PT100 by bearing
Temperature range 20°C to 120°C
Load 2.400 N max.
Speed 6.000 rpm max.
Frequency range 100 Hz to 10 MHz
Common-Mode Voltage 60 V max. (peak to peak)
Connectivity USB, ethernet
Power supply 230 V AC, 50/60 Hz
Scope of delivery FBT adapter (rolling bearing carrier) with sensor cables, mounting mandrel & ball, control unit in Rittal cabinet, "flucon E-LUB" PC software (for Windows OS)
optional accessories Fluid thermostat w/ compressor, set of hoses, laptop


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E-Lub Tester software (included)