Product Data Sheet – ETT Series

Tabletop Demagnetisation Tunnels

The demagnetisation tunnels of the ETT series are designed for tabletop use. The spool current is activated by an ON/OFF switch. The saturation depth of the 50 Hz alternating field is approx. 2mm. The ETT series conforms to IEC Protection Class II (double insulated).

ETT tabletop demagnetisation tunnel

Product Properties and Part Numbers

Standard model Reinforced model
ETT 150 ETT 250 ETT 350 ETT 450 ETT 550 ETT 150 ETT 250 ETT 350 ETT 450 ETT 550
Field strength (kA/m) 11  9  8 6.5 5.4 13.5 10 10 8 6.2
Mains connection (V)  230  230  230  230  230 400 400 400 400 4..
Current consumption (I (A))  1.85  5.5  10  14  16.5 1.6 4.4 8.5 11 12
Power consumption (kVA)  0.5  1.2 2.2  3.1  3.6 0.7 1.8 3.4 4.5 4.7
Frequency (Hz)  50  50  50  50  50 50 50 50 50 50
Measurement A* 260 390 480 580 680  260  390  480  580  680
Measurement B* 150 250 350 450 550  150  250  350  450  550
Measurement C* 260 390 475 577 695  260  390  475  577  695
Measurement D* 166 173 339 330 332  166  173  339  330  332
Part number  101150  101250  101350  101450  101550 101155 101255 101355 101455 101555

*See diagram below for measurement references.  All measurements are in millimetres (mm).

Diagram - ETT

Demagnetisation is an important component of electromagnetic crack testing. Residual magnetism in test samples is an issue for many users and the industry demands increasingly better demagnetisation values.

Where workpieces are subjected to a magnetic field due to a magnetisation process – as part of a testing method, processing, or from magnetic lifting equipment – a residual magnetic field will remain in the component after the fieldgenerating source has been disabled (remanence), which must be neutralised. Eliminating this magnetic residue will help avoid negative effects during later processing or when using the workpieces.

The demagnetisation of AC-supplied spools that have a frequency of 50 Hz, occurs by way of the slow retraction of the test object from the field-filled space of the demagnetisation spool, in direction of the spool axis.

At the start of demagnetisation, the field strength must be at least equal to the field strength of the magnetisation. Similarly, the entire area for demagnetisation must be captured. While a field saturation depth of approx. 2mm can be expected in magnetic particle testing with alternating magnetic field, for components that were manipulated with lifting equipment, the entire cross section of the test object must be covered. In the latter case, demagnetisation is achieved with an increased field saturation depth, whereby the field intensity is decreased with low-frequency AC or reversing DC current.

The most important basis for achieving good demagnetisation results is:

  • for parts that were AC-magnetised: demagnetisation at 50 or 60 Hz AC or low-frequency AC.
  • for parts that were DC-magnetised: demagnetisation with low-frequency AC only (e.g. 16 2/3 Hz).

User Recommendations

NDT Method
Magnetic Particle Testing
Accessories Low-frequency generator 16 2/3 Hz:

AC 230V / 50Hz; Out AC 230V (part number 10700)

AC 400V / 50Hz; Out AC 400V (part number 104710)

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