IEC 60404-11:1991+AMD1:1998+AMD2:2012 CSV

IEC 60404-11
®

Edition 1.2 2012-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Magnetic materials –
Part 11: Method of test for the determination of surface insulation resistance of
magnetic sheet and strip

Matériaux magnétiques –
Partie 11: Méthode d'essai pour la détermination de la résistance d'isolement
superficiel des tôles et feuillards magnétiques

IEC 60404-11:1991+A1:1998+A2:2012

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IEC 60404-11

®


Edition 1.2 2012-05




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE











Magnetic materials –

Part 11: Method of test for the determination of surface insulation resistance of

magnetic sheet and strip




Matériaux magnétiques –

Partie 11: Méthode d'essai pour la détermination de la résistance d'isolement


superficiel des tôles et feuillards magnétiques













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX CD


ICS 17.220.01; 29.030 ISBN 978-2-88912-053-6



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – 60404-11 © IEC:1991+A1:1998
+A2:2012
CONTENTS
FOREWORD . 3
1 Scope and field of application . 5
2 Principle of measurement . 5
3 Test specimen . 6
4 Apparatus . 6
4.1 Contact assembly . 6
4.2 Power supply . 7
4.3 Current measurement . 7
4.4 Determination of applied force . 8
5 Calibration . 9
6 Measuring procedure . 9
7 Evaluation of surface insulation resistance . 9
8 Test report . 10

Figure 1 – Arrangement of apparatus for the measurement of surface insulation resistance . 5
Figure 2 – Arrangement of stabilizing circuit: mode A . 8
Figure 3 – Arrangement of stabilizing circuit: mode B . 8

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60404-11 © IEC:1991+A1:1998 – 3 –
+A2:2012
INTERNATIONAL ELECTROTECHNICAL COMMISSION
–––––––––––

MAGNETIC MATERIALS –

Part 11: Method of test for the determination
of surface insulation resistance of
magnetic sheet and strip



FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

This International Standard has been prepared by IEC technical committee 68: Magnetic alloys
and steels.
This consolidated version of IEC 60404-11 consists of the first edition (1991) [documents
68(CO)69 and 68(CO)76], its amendment 1 (1998) [documents 68/181/FDIS and 68/186/RVD]
and its amendment 2 (2012) [documents 68/434/FDIS and 68/435/RVD].
The technical content is therefore identical to the base edition and its amendments and has
been prepared for user convenience.

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– 4 – 60404-11 © IEC:1991+A1:1998
+A2:2012
It bears the edition number 1.2.
A vertical line in the margin shows where the base publication has been modified by
amendments 1 and 2.

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60404-11 © IEC:1991+A1:1998 – 5 –
+A2:2012
MAGNETIC MATERIALS –

Part 11: Method of test for the determination
of surface insulation resistance of
magnetic sheet and strip



1 Scope and field of application
This International Standard is intended to define a measurement method for the determination
of the characteristics of surface insulation resistance of magnetic sheet and strip.
This method is applicable to magnetic sheet and strip insulated on one or both surfaces and is
suitable for manufacturing control in the application of insulation coatings.
2 Principle of measurement
The principle of the measurement is based on, and includes, the method originally described by
*
Franklin which characterizes only one coated surface at a time.
The arrangement of the apparatus is shown in figure 1. Ten metallic contacts of fixed area are
applied to one coated surface of the sheet, under specified conditions of voltage and pressure.
The effectiveness of the surface insulation is assessed by the measurement of the currents
through the 10 contacts.
Micro-
Power supply
processor
Display
Contact buttons
Twist drill
(a total of 10)
for contact
Insulation
coating
Test specimen
IEC  1 595/98

Figure 1 – Arrangement of apparatus for the measurement of
surface insulation resistance
–––––––––
*
Franklin, R.F., "Measurement and control of interlaminar resistance of laminated magnetic cores", ASTM
Bulletin, no. 144, January 1947, p. 57.

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– 6 – 60404-11 © IEC:1991+A1:1998
+A2:2012
Each contact button is individually fed from a d.c. power supply in one of the two ways which
constitute the two modes of measurement used in this standard, namely:
a) Mode A The voltage between the supply side of the 5 Ω ± 1 % resistors (see figure 2) and
the drill contacts is stabilized at 500 mV ± 0,5 % over a current range of 0 to 1 A. The two
twist drills perform the function of current return contacts with the substrate.
b) Mode B The voltage between each contact button and the drill contacts is stabilized at
250 mV ± 0,5 % over a current range from 0 to 2,5 A for the analysis of individual electrode
currents. The two twist drills perform different functions. One drill provides the current
return contact with the substrate. The other drill serves as a potential sensor for the voltage
feedback control. This method removes the influence of the variable contact resistance
between the current return drill and the substrate.
The voltage across subsidiary current sensing resistors of low-value, connected in series with
each electrode, but not included within the stabilized voltage, serves to indicate the value of the
current, as shown in figures 2 and 3.
Because the current path is between the contacts and the metallic substrate, this is not a true
measurement of interlaminar resistance. However, this test provides a useful indication of
surface insulation quality.
3 Test specimen
Each test specimen shall be formed from a single sheet or length of strip. The width and length
of the test specimen shall be respectively greater than the width and length of the contact
assembly described in clause 4. This measurement is destructive; the test specimen can only
be used once.
To obtain a representative result, test specimens shall be taken from the full sheet width.
4 Apparatus
4.1 Contact assembly
The test specimen is pressed between a plate and the contact assembly. The contact assembly
consists of 10 vertically-mounted metallic rods which move axially against springs in a
mounting block. These 10 contact rods are normally arranged in two rows. However, for
convenience these 10 contacts can be arranged in one row. Each rod shall be provided with a
contact button of bronze or other suitable material (for example, stainless steel) and shall be
electrically insulated from the mounting frame.
NOTE Articulation of contact buttons improves contact by compensating for minor misalignments.
Each of the 10 contact buttons shall have a contact area of 64,5 mm² ± 1 %, giving a total area
for the 10 buttons of 645 mm² ± 1 %.
Electrical contact with the substrate of the test specimen shall be achieved by means of two
spring-loaded twist drills of about 3 mm diameter which pierce the insulation coating.

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60404-11 © IEC:1991+A1:1998 – 7 –
+A2:2012
4.2 Power supply
Mode A: A d.c. power supply capable of maintaining a stabilized voltage of 500 mV across the
electrodes at a current of 0,1 A per electrode (1,0 A total) shall be used.
Mode B: A d.c power supply capable of maintaining a stabilized voltage of 250 mV at a current
of 2,5 A for an individual electrode shall be used. A single supply and a current-sensing
resistor, R can be used and switched to each contact button in turn, or a 10-outlet system can
s,
be used with each electrode fed simultaneously and independently.
4.3 Current measurement
The current flowing through the contact buttons shall be measured with an uncertainty of ± 2%
or better. This can be achieved by inserting a low value (e.g. 0,2 Ω) resistor in the supply to the
contact buttons, at a point outside the connection to the stabilizing circuit, and measuring the
voltage drop across the low value resistor by means of a suitable voltmeter.
The electrical arrangements of the stabilizing circuit and current measurement system are
shown in figures 2 and 3 for modes A and B respectively.

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– 8 – 60404-11 © IEC:1991+A1:1998
+A2:2012


Voltmeter
R
s
Feedback voltage
Stabilized d.c.
Output
power supply
U = 0,5 V
5 Ω 5 Ω 5 Ω 5 Ω 5 Ω 5 Ω 5 Ω 5 Ω 5 Ω 5 Ω
Twist drills
Contact buttons
Test specimen
IEC  471/12

Figure 2 – Arrangement of stabilizing circuit: mode A


Voltmeter
R
s
Feedback voltage
Stabilized d.c.
Output
power supply
U = 0,25 V
Current return
Potential sensor
Twist drills
Test specimen Contact buttons
IEC  472/12

Figure 3 – Arrangement of stabilizing circuit: mode B

4.4 Determination of applied force
The total force applied by all of the contacts pressing on the test specimen shall be determined
by any suitable means with an uncertainty of ±5 % or better.

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60404-11 © IEC:1991+A1:1998 – 9 –
+A2:2012
5 Calibration
The calibration of the system shall be checked in three ways:
a) The electrodes and drills shall be applied to a clean copper sheet at nominal testing
pressure. The total current passing through the 10 electrodes shall be 1,0 A ± 3 % for
mode A. For mode B the electrode to drill voltage shall be less than 25 mV with a current
of 2,5 A flowing. If this is not the case, the electrodes shall be checked for cleanliness and
the twist drills checked for sharpness and contact resistance.
b) Carbon paper pressed onto white paper by the electrodes at nominal testing pressure shall
give a set of even smudges free from signs of force concentration. Pressure measurement
sheets that could indicate applied pressure as colour density variations can be used instead
of the carbon paper and white paper.
c) Standard resistors of 0,1 Ω, 1 Ω, 10 Ω and 100 Ω connected between the drills and each
electrode in turn shall be used to show that the stabilization is adequate and that the
required current levels can be achieved.
6 Measuring procedure
The test specimen shall be positioned between the baseplate and the 10 contact buttons and a
force of 1 290 N ± 5 % shall be gradually applied. This corresponds to a pressure of 2 N/mm²
for the total contact area of 645 mm².
The stabilized d.c. voltage shall be gradually applied to the electrodes and the total current for
mode A, or each electrode current for mode B, shall be recorded individually or by computer.
If the insulation quality of a single surface is to be evaluated in the test, 10 readings shall be
taken using the 10 contact buttons on 10 separate representative areas of the sheet or on 10
test specimens.
If the insulation quality of both surfaces is to be jointly evaluated in the test then five
applications of the contact buttons shall be made to each surface on five separate
representative areas or test specimens. The same area of the test specimen shall not be used
to test both sides.
7 Evaluation of surface insulation resistance
The recorded currents shall be used to calculate reported values of insulation resistance in the
following ways:
a) For Mode A, the coefficient of surface insulation resistance shall be determined by inserting
the 10 values of the current flowing through the 10 electrodes in parallel (either all from one
surface or five from each of the two coated surfaces) in the following formula:
   
   
U R 0,5
   
C = A −  = 645  − 0,5 (1)
10 10
1 10 1
   
  I  I
∑ ∑
A A
   
10 10
 1   1 

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– 10 – 60404-11 © IEC:1991+A1:1998
+A2:2012
where
2
C is the coefficient of surface insulation resistance, in Ω·mm /side
A is the total area of the 10 contact buttons, in mm²
U is the voltage applied to the contacts and 5 Ω resistors, in V
R is the resistance in series with each contact, equal to 5 Ω
I is the measured total electrode current (10 values), in A
A
NOTE If five measurements are taken from each surface, the value C is the coefficient of the surface insulation
resistance of one surface, which represents the mean of the two surfaces of the product.
b) For Mode B, the surface insulation resistance shall be calculated from each of the 100
...