IO/VIDEO,
INFORMATION TECHNOLOGY AND COMMUNICATION TECHNOLOGY
Interpretations of IEC 60065, 6
th
edition.
-------------------------------------
With reference to document 92/80/INF, the following common opinions on interpretation questions
are made available.
Interpretations on the following sub-clauses are included:
-
* Sub-clause 1.1.3
-
* Sub-clause 2.8.11
- Sub-clause
4.3.1
- Sub-clause
4.3.3
- Sub-clause
4.3.10
-
* Sub-clause 8.8
-
* Sub-clause 10.3
-
* Sub-clause 14.2.5
-
* Sub-clause 14.5.1.1
-
* Sub-clause 14.6.2
-
* Sub-clause 14.6.6: test condition
- Sub-clause
14.6.6:
relays
-
Sub-clause 14.6.6: application of voltage / current limits
-
* Sub-clause 14.10.2
- Sub-clause
14.11
- Sub-clause
15.2
This document replaces document 92/82/INF.
Note:
The interpretations given in document 92/82/INF (see items above marked with an asterix) are
included in this document. 108/17/INF
2
Sub-clause 1.1.3: Requirements for altitude - clearances
Question:
Have the factors given in IEC 60664-1, table A.2 to be applied for the determination of clearances at
altitudes above 2000 m?
With respect to the altitude the following requirements are given:
IEC 60065, 5
th
edition: standard applies to 2000 m only.
IEC 60065, 6
th
edition: standard applies to 2000 m only, for higher altitudes special measures might
be necessary.
IEC 60065, 7
th
edition: standard applies to 2000 m only, for higher altitudes reference is made to
IEC 60664-1, table A.2.
Examples of distances (clearance) for reinforced insulation:
As an example an altitude of 3500 m is taken. From Table A.2 of IEC 60664-1 a factor of 1,21 is
found.
230 V mains:
5
th
edition: 6 mm
6
th
edition: 6 mm x factor?
7
th
edition: 4 mm x 1,21 = 4,84 mm
SMPS with Vpeak 600 V:
5
th
edition: 6 mm
6
th
edition: 6 mm x factor 1,21? = 7,26 mm
7
th
edition: 5 mm x 1,21 = 6,05 mm
Interpretation of the WG:
For determining the additional clearance in case of altitudes above 2000 m, the values based on the
7
th
edition are applicable.
Rationale:
The 6
th
edition only indicates that special measures might be necessary. Since the clearance values
in the 6
th
edition are not based on IEC 60664-1 also the factors according to table A.2 of IEC 60664-
1 do not apply in this case.
Action:
No action regarding the text in IEC 60065 is needed. 108/17/INF
3
Sub-clause 2.8.11: Potential ignition sources
Questions:
The interruption of a connection may cause interruption or short circuit of, for example, a
semiconductor device and as a consequence the protective devices operate or the power supply
shut down. In this case the open circuit voltage drops immediately to 0 V.
1)
What is the time frame for checking the steady-state open circuit voltage?
2)
Which voltage has to be taking into account in the evaluation of the potential ignition source?
Interpretations of the WG:
1)
WG1 decided that the measurement shall be done any time after 1 s after opening the
circuit.
2)
WG1 decided that the maximum voltage shall be measured not earlier than 1 s after the
interruption is made.
Rationale:
A minimum time is needed to obtain steady state.
Action:
No action regarding the text in IEC 60065 is needed. 108/17/INF
4
Sub-clause 4.3.1:
Question:
There is an obvious contradiction between sub-clause 4.3.1/4.3.2 and clause 13.1.
The short circuit according to 4.3.1 and 4.3.2 seem to apply in all cases, however, in 13.1 an
exception is introduced.
It is requested to clarify and modify in case this observation is correct.
Interpretation by TC 108/TT92/MT1:
The observation is correct.
Sub-clause 4.3.1 should read as follows:
Except for insulation between parts of different polarity
DIRECTLY CONNECTED TO THE MAINS
, short-
circuit across
CLEARANCES
and
CREEPAGE DISTANCES
if they are less than the values specified in
clause 13 for
BASIC
and
SUPPLEMENTARY INSULATION
.
Rationale:
Clause 4.3.1 of Ed. 5 has been split when producing Ed. 6. The first paragraph was kept in 4.3.1 but
editorially modified; the rest was moved to clause 13.
Sub-clause 13.1 of Ed. 5 was reworded and moved to sub-clause 13.1.1 of Ed. 6.
Clause 4.3.1 is about short-circuiting
CLEARANCE
and
CREEPAGE DISTANCE
for
BASIC INSULATION
and
SUPPLEMENTARY INSULATION
.
Only clause 13.1.1 refers specifically to clause 4.3.1.
Except for insulation between parts of different polarity
DIRECTLY CONNECTED TO THE MAINS
the 3
rd
paragraph of 13.1.1 of IEC 60065 Ed. 6 allows for a smaller
CLEARANCE
. For those smaller distances
4.3.1, 4.3.2 and 11.2 are referenced.
Sub-clause 4.3.1 is not correctly formulated because the exception of 13.1.1 is not repeated here.
Action:
The interpretation above is proposed to be introduced in amendment 1 to IEC 60065, 7
th
edition. 108/17/INF
5
Sub-clause 4.3.3:
Question:
Is the NOTE to sub-clause 4.3.3 applicable to tubes with pressed-glass seals?
The first dashed item of 4.3.3 refers to 'heaters of electronic tubes' and the clause begins with a
reference to 'short-circuit or, if applicable, interruption'. Interruption is, in fact, normally only
applicable to heaters and the interruption of one heater in a chain of heaters connected in series can
cause a hazard.
The application of test short-circuits to parallel-connected tube heaters in low-power equipment, if
carried out, results in operation of the primary circuit fuse(s). However, in high-power audio
amplifiers using tubes (for which there is a significant and growing market), this is not necessarily the
case. The inclusion of fuses directly in the heater circuits results in unreliability due to the stresses
on the fuse cause by the high inrush currents drawn by the heaters. These inrush currents last
longer than those experienced in the primary circuits of electronic products.
Heater short-circuits could be caused in tubes with pinch-seals and moulded bases by failure of the
bond between base and envelope and subsequent rotation of the envelope relative to the base, thus
twisting the lead-out wires together inside the base.
Short-circuit failures of heaters in tubes with pressed-glass seals, which are used in the above-
mentioned amplifiers, are of exceedingly rare occurrence, and test data with contrived short-circuits
shows that such a short-circuit clears without hazard in a very short time.
Interpretation by TC 108/TT92/MT1:
The NOTE to this sub-clause is applicable to the short-circuiting of heaters of tubes with pressed-
glass seals and for that reason no short-circuit test is needed.
Action:
No action regarding the text in IEC 60065 is needed. 108/17/INF
6
Sub-clause 4.3.10:
Question:
Experience has shown that testing in accordance with 4.3.10 has created problems.
Examples given in the dashed paragraphs have resulted in different interpretations with regard to
performance of the testing.
It is requested to provide guidance on the testing.
Interpretation by 108/TT92/MT1:
MT1 is of the opinion that clause 4.3.10 should be understood as follows:
Surfaces having ventilation openings that are likely to be obstructed simultaneously shall be covered
one at a time with a piece of semi-rigid sheet material and tested. No test is to be applied to sloped
surfaces with an angle greater than 30
o
from the horizontal.
The following modification addresses this problem.
The top, sides and the back of an apparatus, if such surfaces have ventilation openings, shall be
covered one at a time with a piece of card of 200 g/m
2
density

with dimensions not less than each
tested surface, covering all openings.
Openings on different surfaces on top of the apparatus (if any) are covered simultaneously
by separate pieces of card.
Openings on top of the apparatus, on a surface inclined at an angle greater than 30 degrees
to the horizontal, from which an obstruction is free to slide, are excluded.
On the back and the sides of the apparatus, the card is attached to the upper edge and
allowed to hang freely.
Note There is no test for the bottom surface.
Rationale:
Complete obstruction of openings on the rear and both sides at the same time is not likely to occur.
Moreover it is not likely that an object obstructing the ventilation will remain in place on a sloped
surface.
Covering the openings on the top simultaneously by separate pieces of card is the possible way to
ensure reproducibility of testing. In a case of the top having form of a stairs with for example two
steps plus a slope (more or less than 30 degrees) use of one piece of card or material would
inevitably lead to different results at different test houses.
Action:
The above modification is proposed to be introduced in amendment 1 to IEC 60065, 7
th
edition. 108/17/INF
7
Sub-clause 8.8: Use of non-separable thin sheet insulation:
Question:
Current technology is utilising non-separable thin sheet insulation within transformers for the
provision of supplementary and /or reinforced insulation.
How should such non-separable insulation be assessed for suitability in these applications?
Interpretation of the WG:
The current published requirements in the standard do not adequately address the use on non-
separable thin sheet insulation.
The following amendment to the standard will be published to address this issue:
add to clause 8.8
For requirements for non-separable thin sheet insulation in two or more layers, see 8.xx
add new clause 8.xx
8.xx Requirements for non-separable thin sheet insulation in two or more layers
Three separate test specimens of the sheet, of 70 mm, width shall be supplied by the manufacturer.
The test is carried out by fixing a specimen on a mandrel made of steel, nickel plated, or brass with
smooth surface finish