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Electromagnetic Core Imperfection Detection (ELCID) Testing

ELCID Testing of Core Imperfections in Generators using Rover Robots

Generators are crucial components in an industrial power plant and are designed to operate reliably for many years. One of the most expensive parts of a 3-phase generator is the stator, which is where the energy from the magnetic field is converted into electrical energy. The condition of the generator and its core deteriorates over time, increasing the likelihood of failures. Quantitative testing and periodic inspections of the generator core are necessary to avoid unplanned outages. ARGIS enables inspections to be carried out not only when the rotor has been removed, but also with the rotor still in place, thus saving you time, effort and money.

Major Savings, for In Situ Inspection with ARGIS: Less Manpower is required to prepare the Generator for Inspection (0.5-3 shifts instead of up to several weeks)

  • Reduction of outage costs up to EUR 300,000

  • Reduction of lost productivity due to outage time (which can amount to millions of euros)

  • Fewer risks of damage to the generator

  • A generator inspection can stay out of the critical path of an outage

  • High reproducibility

  • All data is stored for future comparison and data trending

  • Low flux leakage testing with excitation through rotor forging reduces dismantling of the generator

  • Better anticipation and planning possible for next major outage (plan repair work or postpone)

  • ARGIS can be combined with in-situ retaining ring testing (KIRR)

Low Flux Leakage Test (LFCT, also called ELCID)


A chain containing motor drives and a docking station for the Generator Inspection Vehicle (GIV) is mounted around one of the retaining rings of the generator. The chain is positioned accurately in front of each slot so that the GIV can be inserted into a gap as small as 17 mm (0.67 inch) and up. The GIV then moves to the other end of the stator core and back in order to perform the LFCT, Wedge tightness test and visual inspections all in the same run to save time.

Low flux leakage test

Electromagnetic core flux leakage testing (ELCID or equivalent) is a standard feature. The step irons are measured with a separate module.

Wedge tightness testing

The GIV is provided with a stator wedge tap tester that

determines the wedge tightness based on spectral analysis of the sound response.

Visual testing

The GIV is equipped with 4 camera modules: a forward-viewing camera is used for general inspection of the stator teeth and wedges, another camera inspects the rotor body and cooling slots, and 2 further cameras inspect the stator cooling slots.

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