CEI EN 60404-15

This part of IEC 60404 specifies a solenoid method, a magnetic
moment method, a magnetic balance method and a permeability meter
method for the determination of the relative magnetic permeability
of feebly magnetic materials (including austenitic stainless
steel). The magnetic balance and permeability meter methods are
both comparison methods calibrated using reference materials to
determine the value of the relative magnetic permeability of the
test specimen. The relative magnetic permeability range for each of
these methods is shown in Table 1. The methods given are for
applied magnetic field strengths of between 5 kA/m and 100
kA/m.

NOTE 1 The relative magnetic permeability range given for the
magnetic balance method covers the inserts provided with a typical
instrument. These can only be assessed at values for which
calibrated reference materials exist.

NOTE 2 For a relative magnetic permeability larger than 2, a
reference material cannot be calibrated using this written
standard. A note of this is given in the test report explaining
that the values measured using the magnetic balance are for
indication only.

The solenoid method is the reference method. The magnetic moment
method described is used mainly for the measurement of the relative
magnetic permeability of mass standards.

Two comparator methods used by industry are described. These can
be calibrated using reference materials for which the relative
magnetic permeability has been determined using the reference
method. When suitable, the magnetic moment method can also be used.
The dimensions of the reference material need to be given careful
consideration when determining the uncertainty in the calibration
value due to self-demagnetization effects. See Annex A for more
information on correcting for self-demagnetization.