EN 60051-9:1989

SLOVENSKI SIST EN 60051-9:1995
prva izdaja
STANDARD
avg 1995
Neposredni kazalni analogni električni merilni instrumenti in njihov pribor –
9. del: Priporočene preskusne metode (IEC 60051-9:1988)
Direct acting indicating analogue electrical measuring instruments and their
accessories - Part 9: Recommended test methods (IEC 51-9:1988)
ICS 17.220.20 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

NORME CEI
IEC
INTERNATIONALE
51-9
INTERNATIONAL
Quatrième édition
STANDARD
Fourth edition
Appareils mesureurs électriques
indicateurs analogiques à action directe
et leurs accessoires
Neuvième partie:
Méthodes d'essai recommandées
Direct acting indicating analogue
electrical measuring instruments
and their accessories
Part 9:
Recommended test methods
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51-9 (4) © IEC - 3
CONTENTS
Page
FOREWORD 5
PREFACE 5
Clause
1. Scope and general test conditions 9
2. Intrinsic error tests 17
3. Variation tests 33
4. Other tests
5. Index of tests and test conditions 129

51-9 (4) © [EC - 5
INTERNATIONAL ELECTROTECHNICAL COMMISSION
DIRECT ACTING INDICATING ANALOGUE ELECTRICAL MEASURING
INSTRUMENTS AND THEIR ACCESSORIES
Part 9: Recommended test methods
FOREWORD
The formal decisions or agreements of the IEC on technical matters, prepared by Technical
1)
Committees on which all the National Committees having a special interest therein are
represented, express, as nearly as possible, an international consensus of opinion on the
subjects dealt with.
They have the form of recommendations for international use and they are accepted by the
2)
National Committees in that sense.
expresses the wish that all
3) In order to promote international unification, the IEC
National Committees should adopt the text of the IEC recommendation for their national
rules in so far as national conditions will permit. Any divergence between the IEC recom-
mendation and the corresponding national rules should, as far as possible, be clearly
indicated in the latter.
PREFACE
This standard has been prepared by IEC ,Technical Committee No. 85:
Measuring equipment for basic electrical quantities (former Sub-
Committee 13B: Electrical measuring instruments).
This fourth edition replaces the third edition of IEC Publication 51.
This standard constitutes Part 9.
The general layout for the revised Publication 51 is as follows:
Definitions and general requirements common to all parts.
Part 1:
Special requirements for ammeters and voltmeters.
Part 2:
Part 3: Special requirements for wattmeters and varmeters.
Part 4: Special requirements for frequency meters.
Part 5: Special requirements for phase meters, power factor meters
and synchroscopes.
Part 6: Special requirements for ohmmeters (impedance meters) and
conductance meters.
Part 7: Special requirements for multi-function instruments.

51-9 (4) e IEC - 7
Part 8: Special requirements for accessories.

Part 9: Recommended test methods.
Part 9 is not complete in itself as it contains no requirements. The
requirements are contained in Parts 1 to 8 and include references to the
test sub-clauses of Part 9.
Three tests specified in Part 9 have no corresponding requirements in
Parts 1 to 8 but are included to permit standardization of the test methods
for characteristics that are normally specified by agreement between the
manufacturer and the user. These tests are:
Pull-in difference frequency
Tracking error
Simultaneous influence of voltage and power factor.
The text of this standard is based on the following documents:
Six Months' Rule Report on Voting
13B(C0)105 85(C0)5
Full information on the voting for the approval of this standard can be
found in the Voting Report indicated in the above table.

51-9 (4) © IEC - 9
DIRECT ACTING INDICATING ANALOGUE ELECTRICAL MEASURING
INSTRUMENTS AND THEIR ACCESSORIES
Part 9: Recommended test methods
1. Scope and general test conditions
1.1
Scope
Part 9 of Publication 51 contains recommended test methods for direct
acting indicating analogue electrical measuring instruments and their
accessories.
1.2 General test conditions
The test methods described in this part shall be applied under the
following conditions unless otherwise specified.
1.2.1 Reference conditions
Reference conditions shall be according to Table I of the relevant
part. Where a reference range is specified, tests shall be performed at
both limits of the reference range.
1.2.2
Parallax
Note.- Care should be taken to avoid the effect of parallax error
when taking instrument readings.
For an edgewise instrument, the line of vision should be perpendi-
cular to the instrument dial at the index tip.
For an instrument having a mirror scale, the line of vision should be
such that the index tip is coincident with its reflection in the mirror.
1.2.3 Tapping
Immediately prior to taking a reading, either the instrument or its
support shall be tapped lightly as with a finger or the eraser end of a
pencil.
51-9 (4) © IEC -
11 -
However, tapping is not permitted in certain tests such as those for
determining intrinsic error, return to zero and the effects of shock
and vibration, as stated in these test methods.
1.2.4
Thermal stability
All instruments shall be allowed to remain at the reference tempera-
ture long enough to eliminate temperature gradients.
Note.-
Two hours will usually be sufficient.
1.2.5 Preconditioning time
See Part 1: Sub-clause 3.3.1.
1.2.6
Zero adjustment (mechanical)
With the instrument disconnected from all supplies and before each
set of readings is taken, the index shall be set on the zero scale mark
or to an appropriate reference mark on the scale using the mechanical
zero adjuster, as follows:
1)
Operate the zero adjuster in a direction which will drive the index
toward the zero mark of the instrument.
2)
While continuing to drive the index in the direction selected in 1),
set the index on the zero mark while tapping the instrument case.
Once the direction of drive has been selected, do not change it
until the index is on the zero mark.
3)
With the index set on the zero mark, reverse the direction of
motion of the zero adjuster, and drive it far enough to introduce
mechanical freedom (play) in the zero adjuster, but not far enough
to disturb the position of the index.
Exception: Instruments without zero adjuster or where the mechanical
zero does not appear on scale shall not be reset.
1.2.7 Zero adjustment (electrical)
Before each set of readings, the index shall be set on the reference
mark with the electrical zero adjuster. Refer to the manufacturer's
instructions for details of this adjustment.

51-9 (4) © IEC - 13 -
1.2.8 Test equipment errors
All tests shall be made using reference instruments having an
intrinsic error no more than one-fourth of that corresponding to the
accuracy class of the instrument under test. However, the use of
reference instruments having an intrinsic error no more than one-tenth
of that corresponding to the accuracy class of the instrument under
test is strongly recommended.
When testing for variations avoid, if possible, applying the influence
quantity (e.g. temperature) to the reference instrument. Otherwise,
ensure that the reference instrument is not affected by more than
one-fourth of the permissible variation of the instrument under test,
where both are subjected to the same influence quantity (e.g. change
of frequency) .
Manufacturers shall make allowance for reference instrument un-
certainty to ensure that all instruments are within their error limits at
the time of shipment. In contrast, a user shall add the errors of his
reference instrument to the permitted error when rechecking an ins-
trument and the resulting sum shall be used for the limit for that test.
Nothing in these recommendations is intended to prevent the use of
special test methods and/or specialized test equipment for making
testing simpler and/or more accurate.
1.2.9 Reading methods
Whenever possible, tests shall be conducted by setting the instru-
ment under test to a scale mark and reading the reference instrument.
Note.-
The reference instrument should have an adequate scale reso-
lution (or number of digits) to enable readings to be taken
with a resolution at least as good as that corresponding to
one-fifth of the accuracy class of the instrument under test.
1.2.10 Polyphase testing
Polyphase instruments may be tested by connecting to an appropriate
polyphase supply with properly measured and controlled voltages,
currents and phase angles.
51-9 (4) © IEC - 15 -
If single-phase testing of polyphase instruments is permitted by the
manufacturer, the current coils may be connected in series and the
voltage coils in parallel. In all cases, follow the manufacturer's
instructions for details of connections and the application of calibration
constants.
1.2.11 A.C.
instrument testing on d.c.
Some a.c. instruments, for example electrodynamic, thermal or
electrostatic instruments, may be tested on d.c. if permitted by the
manufacturer. If this is the case, perform the tests as specified for
the instrument but use a d.c. supply and neglect references to power
factor and phase angle. For these cases, the errors are computed from
the average of the results from testing with the reversal of polarity of
each measuring circuit. Other tests relating to a.c. variations may not
apply.
1.2.12 Multirange and multifunction instruments
All ranges and all functions shall be tested separately. Instruments
with multiple supply voltage capability shall be tested separately on
each supply connection.
1.2.13 Test leads
If test leads are specified by the manufacturer they shall be used
for these tests. Otherwise, the size and placement of leads used in the
performance of these tests shall be such that they do not influence the
test results.
1.2.14
Ohmmeter testing
For high value test resistors, the insulation of the test leads shall
be adequate to ensure that the test resistor is not shunted to cause
errors greater than one-tenth of the rated intrinsic error of the
ohmmeter.
For low value resistors, the total resistance of the test leads shall
be allowed for unless it is negligible in comparison with the value of
the test resistor.
Ohmmeters having special leads terminating in spikes may need
special test resistors having terminals capable of accepting the spikes.

51-9 (4) © IEC - 17 -
Ohmmeters measuring the values of 4-terminal resistors may need
special test resistors.
Care shall be taken when testing high voltage ohmmeters that the
voltage rating of the test resistor is not exceeded. This is ` necessary
both because of the danger of insulation breakdown and because of the
possibility of the test resistor having a significant voltage coefficient.
If an ohmmeter has a stated value of test voltage when measuring a
stated value of test resistance (or an open circuit), the voltage should
be measured using a voltmeter having a permissible error not exceed-
ing 1% of the test voltage. Where the voltage is to be measured at a
definite value of test resistance, the voltmeter may be shunted to
obtain this value. An electrostatic voltmeter, when shown to be ade-
quately free from leakage, will be suitable for carrying out the open
circuit voltage test.
Note.- An electronic d.c. voltmeter may be used but care should be
taken to avoid the effects of input offset voltage and current.
Care shall be taken that the test resistor will not be damaged by the
current supplied by the ohmmeter.
When an ohmmeter has a hand-driven 'generator, it should be turn-
ed, as nearly as possible, at a uniform speed and at the speed stated
by the manufacturer. If a slipping clutch is provided, the turning
speed should be about 10% higher than the clutch slipping speed.
2. Intrinsic error tests
2.1 Ammeters and voltmeters
2.1.1 Procedure
1) If relevant, set zero with tapping.
2)
Apply sufficient slowly increasing excitation to bring the index
sequentially to each of at least five approximately equidistant scale
marks (BX) including the lower and upper limits of the measuring
range without tapping. Record the values of excitation (B
R) as
shown by the reference instrument.

51-9 (4) © IEC - 19 -
3) Increase the excitation .to 120% of the value corresponding to the
upper limit of the measuring range or to cause the index to reach
the upper limit of its travel, whichever is the less. Immediately
and slowly reduce the excitation to bring the index sequentially to
the same scale marks (B X
) as in step 2) without. tapping. Record
the values of excitation (B R)
as shown by the reference
instrument.
Note. - For instruments in which the zero is displaced within the
scale, these tests should be performed on both sides of the
zero scale mark as appropriate.
2.1.2 Computation
The intrinsic error, expressed as a percentage, shall be computed
for each selected scale mark as follows:
x 100
A F
BR )
where AF
is the fiducial value
2.2 Wattmeters and varmeters
2.2.1 Procedure
1) If relevant, set zero with tapping.
2) Energize the voltage circuits at rated voltage within ±2%.
3)
Apply sufficient slowly increasing current to bring the index
sequentially to each of at least five approximately equidistant scale
marks X)
(B including the lower and upper limits of the measuring
range without tapping. Record the values of excitation (B
R) as
shown by the reference instrument.
4) Increase the current to 120% of the value corresponding to the
upper limit of the measuring range or to cause the index to reach
the
...