EN 61298-3:1998

SLOVENSKI STANDARD
01-november-1998
Process measurement and control devices - General methods and procedures for
evaluating performance - Part 3: Tests for the effects of influence quantities (IEC
61298-3:1998)
Process measurement and control devices - General methods and procedures for
evaluating performance -- Part 3: Tests for the effects of influence quantities
Prozeßmeß-, -steuer- und -regelgeräte - Allgemeine Methoden und Verfahren für die
Bewertung des Betriebsverhaltens -- Teil 3: Prüfungen für die Wirkungen von
Einflußgrößen
Dispositifs de mesure et de commande de processus - Méthodes et procédures
générales d'évaluation des performances -- Partie 3: Essais pour la détermination des
effets des grandeurs d'influence
Ta slovenski standard je istoveten z: EN 61298-3:1998
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

NORME
CEI
INTERNATIONALE
IEC
61298-3
INTERNATIONAL
Première édition
STANDARD
First edition
1998-02
Dispositifs de mesure et de commande
de processus –
Méthodes et procédures générales d'évaluation
des performances –
Partie 3:
Essais pour la détermination des effets
des grandeurs d'influence
Process measurement and control devices –
General methods and procedures for
evaluating performance –
Part 3:
Tests for the effects of influence quantities
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61298-3 © IEC:1998 – 3 –
CONTENTS
Page
FOREWORD . 7
INTRODUCTION . 9
Clause
1 Scope. 11
2 Normative references . 11
3 Definitions . 13
4 General considerations . 15
4.1 Criteria . 15
4.2 General procedures . 15
5 Ambient temperature effects . 17
5.1 Criteria . 17
5.2 Test procedure . 17
6 Ambient relative humidity effects. 19
7 Vibration. 21
7.1 General considerations . 21
7.2 Initial resonance search. 23
7.3 Endurance conditioning by sweeping. 23
7.4 Final resonance search. 23
7.5 Final measurements . 23
8 Shock, drop and topple . 23
9 Mounting position. 25
10 Over-range . 25
11 Output load effects . 27
11.1 Electrical output. 27
11.2 Pneumatic output. 27
12 Power supply effects. 27
12.1 Supply voltage and frequency variations. 27
12.2 Transient supply voltage effects. 29
12.3 Supply voltage depression . 29
12.4 Short-term supply voltage interruptions . 31
12.5 Fast transient/burst immunity requirements . 31
12.6 Surge immunity requirements . 33
12.7 Reverse supply voltage protection (d.c. devices) . 33
12.8 Supply pressure variations. 33
12.9 Supply pressure interruptions. 33
13 Electrical interference . 35
13.1 Common mode interference. 35
13.2 Normal mode interference (series mode) . 37
13.3 Earthing. 39

61298-3 © IEC:1998 – 5 –
Clause Pages
14 Harmonic distortion effects . 39
15 Magnetic field effects. 41
16 Radiated electromagnetic interference . 43
16.1 General considerations . 43
16.2 Procedure. 45
17 Electrostatic discharge. 47
17.1 General considerations . 47
17.2 Procedure. 47
18 Effect of open-circuited and short-circuited input . 51
19 Effect of open-circuited and short-circuited output . 51
20 Effects of process medium conditions . 51
20.1 Temperature of process fluid . 51
20.2 Flow of process fluid through the device. 53
20.3 Static line pressure effect . 53
21 Atmospheric pressure effects. 55
22 Flow of purge gas through the device. 55
23 Accelerated operational life test . 55
24 Operational long-term drift test. 57

61298-3 © IEC:1998 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
–––––––––––
PROCESS MEASUREMENT AND CONTROL DEVICES –
GENERAL METHODS AND PROCEDURES
FOR EVALUATING PERFORMANCE –
Part 3: Tests for the effects of influence quantities
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61298-3 has been prepared by subcommittee 65B: Devices, of IEC
technical committee 65: Industrial-process measurement and control.
The text of this standard is based on the following documents:
FDIS Report on voting
65B/320/FDIS 65B/331/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
IEC 61298 consists of the following parts, under the general title Process measurement and
control devices – General methods and procedures for evaluating performance:
– Part 1: 1995, General considerations
– Part 2: 1995, Tests under reference conditions
– Part 3: 1997, Tests for the effects of influence quantities
– Part 4: 1995, Evaluation report content

61298-3 © IEC:1998 – 9 –
INTRODUCTION
This standard is not intended as a substitute for existing standards, but is rather intended as a
reference document for any future standard developed within the IEC, or other standards
organizations, concerning the evaluation of process instrumentation. Any revision of existing
standards should take this standard into account.
This common standardized basis should be utilized for the preparation of future relevant
standards, as follows:
– any test method or procedure, already treated in this standard, should be specified and
described in the new standard by referring to the corresponding clause of this standard;
– any particular method or procedure, not covered by this standard, should be developed and
specified in the new standard in accordance with the criteria, as far as they are applicable,
stated in this standard;
– any conceptual or significant deviation from the content of this standard should be clearly
identified and justified if introduced in a new standard.

61298-3 © IEC:1998 – 11 –
PROCESS MEASUREMENT AND CONTROL DEVICES –
GENERAL METHODS AND PROCEDURES
FOR EVALUATING PERFORMANCE –
Part 3: Tests for the effects of influence quantities
1 Scope
This part of IEC 61298 specifies general methods and procedures for conducting tests and
reporting on the functional and performance characteristics of process measurement and
control devices. The tests are applicable to any such devices characterized by their own
specific input and output variables, and by the specific relationship (transfer function) between
the inputs and outputs, and include analogue and digital devices. For devices that require
special tests, this part of IEC 61298 is to be used, together with any product-specific standard
specifying special tests.
This part of IEC 61298 covers tests for the effects of influence quantities.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 61298. At the time of publication, the editions indicated
were valid. All normative documents are subject to revision and parties to agreements based
on this part of IEC 61298 are encouraged to investigate the possibility of applying the most
recent editions of the normative documents indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
IEC 60068-2-3:1969, Environmental testing – Part 2: Tests – Test Ca: Damp heat, steady state
IEC 60068-2-6:1995, Environmental testing – Part 2: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-31:1969, Environmental testing – Part 2: Tests – Test Ec: Drop and topple,
primarily for equipment-type specimens
IEC 60654-1:1993, Industrial-process measurement and control equipment – Operating
conditions – Part 1: Climatic conditions
IEC 60902:1987, Industrial-process measurement and control – Terms and definitions
IEC 61000-4-2:1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 2: Electrostatic discharge immunity test. Basic EMC publication
IEC 61000-4-3:1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 3: Radiated, radio-frequency, electromagnetic field immunity test. Basic
EMC publication
61298-3 © IEC:1998 – 13 –
IEC 61000-4-4:1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 4: Electrical fast transient/burst immunity test. Basic EMC publication
IEC 61000-4-5:1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 5: Surge immunity test
IEC 61298-1:1995, Process measurement and control devices – General methods and
procedures for evaluating performance – Part 1: General considerations
IEC 61298-2:1995, Process measurement and control devices – General methods and
procedures for evaluating performance – Part 2: Tests under reference conditions
IEC 61298-4:1995, Process measurement and control devices – General methods and
procedures for evaluating performance – Part 4: Evaluation report content
3 Definitions
For the purpose of this part of IEC 61298 the following definitions apply. Those marked with an
asterisk (*) are identical to those given in IEC 60902, but that document has additional notes.
3.1
DUT
device under test
3.2
influence quantity
test parameter chosen to represent a condition representing one aspect of the environment
under which a device may operate
3.3
variable*
quantity or condition whose value is subject to change and can usually be measured (e.g.
temperature, flow rate, speed, signal, etc.)
3.4
signal*
physical variable, one or more parameters of which carry information about one or more
variables which the signal represents
3.5
range*
region of the values between the lower and upper limits of the quantity under consideration
3.6
span*
algebraic difference between the upper and lower limit values of a given range
3.7
unexpected event
device breakdown, failure to work, anomaly, or inadvertent damage occurring during an
evaluation which requires correction by the device manufacturer
3.8
test procedure
statement of the tests to be carried out, and the conditions for each test, agreed between the
manufacturer, the test laboratory, and the purchaser/user before the evaluation starts

61298-3 © IEC:1998 – 15 –
4 General considerations
4.1 Criteria
Unless otherwise stated, any effects of the tests described in this standard shall be assessed
by determining the change in the functional and performance characteristics due to the single
influence quantity applied.
Rates of change of influence quantities shall be sufficiently slow to ensure that no overshoot of
the influence quantities occurs at any point in the DUT. Sufficient time shall be allowed for
stabilization at each value or state of the influence quantity before taking readings. It may be
useful to check, by means of specific measurements of the effects, whether the influence
quantities cause variations in the characteristics of the DUT other than those addressed in this
standard.
In the case of discontinuous-output devices such as alarms, the tests shall be conducted to
establish the effects of the specified influence.
Only that influence quantity for which a specific test is being conducted shall be applied during
a specified test. All other influences shall be maintained at the reference operating conditions.
However, consideration shall be given to any combination of two or more influence quantities
which may aggravate the operating conditions (e.g. for an electrical device, temperature and
supply voltage).
The limit values of influence quantities specified in this standard should be used if no other
limit values are specified by the manufacturer or by the user, and results of testing at these
values can be added to the report by agreement.
4.2 General procedures
The procedures used for the determination of the effects of influence quantities depend on the
kind of test, on the type of device and on its most significant characteristics (e.g. zero, span,
etc.).
The procedures should be established in accordance with the criteria given in 5.1 and 5.2 of
IEC 61298-1 in order to avoid tests which are too severe.
To satisfy these criteria, the DUT should be tested by assessing the effects of all the quantities
which might influence the performance of the DUT: this general statement is strictly valid for
performance evaluation and for type tests.
For routine and sampling tests, only the influence quantity which is considered to have the
most effect or is agreed between the parties should be applied. Wherever possible, all the tests
shall be carried out by measurement of the change of the output of the DUT.
The deviations caused by the effect of the specific influence quantity should be expressed
generally as a percentage of the output span. On certain devices, it may be more convenient to
express it in terms of the input span (see 4.1.6 of IEC 61298-2). It is important that the input
should be set so that the output is not limited; so in all tests, inputs corresponding to, for
example, 5 % and 95 % may be used instead of 0 % and 100 %. For the same reason, tests
that can produce large deviations on output (for example, supply voltage interruptions,
electrical fast transients, and so on) may be executed at input levels held at a value which
produces 50 % output signal.
61298-3 © IEC:1998 – 17 –
In the case of discontinuous output devices such as alarms, the tests shall be conducted in the
same way to establish the conditions at which the performance is affected, with the
alarm/switching level set to 10 % above or below the nominal output.
5 Ambient temperature effects
5.1 Criteria
Sufficient time shall be allowed at each test temperature to permit thermal stabilization of the
DUT before test measurements are taken.
The stabilization period is a function of the DUT mass and of energy dissipation. It is normally
checked by recording the output signal of the DUT. It may be as long as 3 h.
Whatever the temperature cycle prescribed, during the temperature cycles at low and high
temperature, it is important to carry out the measurements at the same temperatures during
repeat cycles so as to permit comparison.
Pneumatic devices shall have sufficient air supply tubing inside the test chamber to ensure that
the supply and input air are at the same temperature as the DUT.
5.2 Test procedure
The effects of ambient temperature shall be measured in the temperature range specified by
the manufacturer or, if no value is specified, between the limits shown in table 1.
The test limits for ambient temperature should be appropriate to the temperatures at the
intended operational location of the DUT.
The test shall be carried out by conducting the same performance test at each selected test
ambient temperature, beginning at the reference temperature (+20 °C).
Table 1 – Ambient temperature test ranges
Temperature Temperature Typical service
°C class (IEC 60654-1) application
min. max.
+5 +40 B2 Indoors or sheltered locations
0 +55 – Indoors in hot locations
–25 +55 C2 Outdoor locations
–50 +40 D2 For extreme outdoor locations
The test ambient temperatures should be chosen generally at 20 °C intervals, up to the
specified limit temperatures for the DUT.
For example, for the temperature class D2, the test temperature cycle should be +20 °C
(reference), +40 °C, +60 °C, +85 °C, +20 °C, 0 °C, –20 °C, –40 °C, +20 °C.
If agreed by all parties in the test programme, a test at only four temperatures, 20 °C
(reference), maximum, minimum, and 20 °C, may be sufficient.

61298-3 © IEC:1998 – 19 –
The tolerance for each test temperature should be ±2 °C and the rate of change of ambient
temperature should be less at 1 °C per minute. No adjustments to the DUT shall be made
during the test cycle.
A second or third temperature cycle, without any adjustment of the DUT, may be specified in
the test programme. At each test temperature, data shall be recorded for increasing and
decreasing values of output at each 25 % of span.
The output changes at each test value shall be calculated from the average of the upscale and
downscale readings and reported in per cent of ideal output span. Any significant changes in
hysteresis, linearity or repeatability shall also be calculated and reported. See IEC 61298-4.
Any effects on a digital display indicator shall also be reported, including loss of contrast,
brightness, distortion or missing bits.
6 Ambient relative humidity effects
The effects of ambient relative humidity shall be determined by placing the DUT in a humidity
test chamber in which the value of relative humidity should be controlled within +2 % to 3 % of
the specified relative humidity levels (as specified in IEC 60068-2-3).
The DUT shall be stabilized at the reference relative humidity <60 % at the temperature of
40 °C ± 2 °C.
Measurements shall be taken at each 25 % of output span in each direction.
+2
The relative humidity shall then be increased in not less than 3 h to (93 ) % avoiding the
−3
deposition of condensation on the DUT and maintained at this value for a period of at least
48 h. If agreed in the test programme, the DUT may be un-energized during this period.
The measurements shall again be taken at 25 % intervals of output span in each direction.
With the DUT remaining in operation, the relative humidity shall be reduced in not less than 3 h
to the original reference value of <60 %.
After stabilization for at least 12 h, the measurements shall be repeated.
Any changes in lower range value and span shall be calculated and reported in per cent of
output span.
In addition, any significant changes in hysteresis, linearity or repeatability should be calculated
and reported.
In addition, a visual examination shall be made after the test to check for indications of
component deterioration or moisture having entered sealed enclosures.

61298-3 © IEC:1998 – 21 –
7 Vibration
7.1 General considerations
The general procedures of this test comply with the procedure described in IEC 60068-2-6.
The effect of vibration shall be determined by the following procedure using the peak
amplitudes, acceleration levels, and frequency ranges specified by the manufacturer.
In the absence of manufacturer's specifications, one of the following test conditions (see
table 2) related to the application environment of the device shall be used.
Measurements shall be made before and after the vibration exposure.
The DUT shall be mounted, in accordance with the manufacturer's instructions for a normal
installation, on a vibration table where it shall be subjected to rectilinear sinusoidal vibrations in
each of three mutually perpendicular axes, one of which shall be the vertical.
The rigidity of the vibration table and of the mounting means for the DUT shall be such that the
vibration is transferred to the normal mounting point of the DUT with a minimum of loss or gain.
The test vibration level shall be measured at the normal mounting point of the DUT.
Vibrations shall be applied with the DUT powered and operating with 50 % input signal.
The output signal shall be recorded to document any changes in output.
Table 2 – Vibration test levels
Typical Test Displacement Acceleration
application frequency range peak amplitude amplitude
mm
m/s
Control room or field with low 10 to 150 0,075 9,8
vibration level
Field with general application or 10 to 500 0,15 19,6
pipe-line with low vibration
Field with high vibration level or 10 to 2 000 0,21* 29,4*
pipe line with high vibration or
0,35 49
* Not derived from IEC 60068-2-6.
NOTE – The crossover frequency between constant amplitude and constant acceleration is nominally 60 Hz.
Displacement is the criterion below the crossover, and acceleration is the criterion above it.
The vibration tests shall include three stages:
– an initial resonance search;
– an endurance conditioning by sweeping the frequency over the appropriate frequency range
specified in table 2, or as specified by the manufacture or by the user;
– a final resonance search.
These three stages shall be performed in sequence. At each stage, the DUT shall be vibrated
in each of the three major axes before proceeding to the next stage.

61298-3 © IEC:1998 – 23 –
7.2 Initial resonance search
The initial resonance search shall be carried out to study behaviour of the DUT to determine
any component resonances and the corresponding resonance frequencies, and to obtain
information for comparison with the final resonance search.
The sweep rate shall be not greater than 0,5 octave per minute.
During the resonance search, frequencies shall be noted which cause
a) significant changes in the output signal;
b) mechanical resonances of components or sub-assemblies.
All the amplitudes and frequencies at which these effects occur shall be noted in order to be
compared with those found during the final resonance search specified below.
7.3 Endurance conditioning by sweeping
The test is carried out by sweeping the vibration frequency at a rate of one octave per minute
over the range selected.
The total number of sweep cycles should be 60, being 20 in each of the three mutually
perpendicular directions.
7.4 Final resonance search
The final resonance search shall be made in the same way as the initial resonance search and
with the same vibration characteristics.
The resonance frequencies, and the frequencies which cause significant changes in the output
signal, found in the initial resonance search and final resonance search shall be compared.
7.5 Final measurements
The satisfactory mechanical condition of the DUT shall be verified at the end of the tests with a
visual examination for any deformation or cracks in the components or mountings.
The satisfactory performance of the DUT shall be verified with a measurement test; any
change in the lower range value and span shall be recorded in per cent of output span.
8 Shock, drop and topple
The test shall be made according to the test procedure Ec of IEC 60068-2-31.
Before the test, reference measurements of lower range-value and span shall be recorded.
During the test, the power supply and inputs may be switched off.

61298-3 © IEC:1998 – 25 –
The object of this test is
– to represent knocks and jolts likely to occur during repair work or rough handling in use;
– to verify the minimum degree of mechanical ruggedness.
The procedure of "dropping on to a face" shall be applied as follows:
The DUT, standing in its normal position of use on a smooth, hard, rigid surface of concrete or
steel, is tilted about one bottom edge so that the distance between the opposite edge and the
test surface is 25 mm, 50 mm or 100 mm (value chosen by agreement between manufacturer
and use), or so that the angle made by the bottom and the test surface is 30°, whichever
condition is the less severe. It is then allowed to fall freely onto the test surface.
The DUT shall be subjected to one drop about each of the four bottom edges.
After this test, the DUT shall be examined for damage.
Any change in lower range-value and span shall be recorded.
If any changes are noted, it shall be verified that the DUT can be readjusted so that the initial
performance can be re-established.
NOTE – In special cases, by agreement, one of the other shock tests in IEC 60068-2-31 may be used.
9 Mounting position
Where the DUT might be position sensitive, the change in lower range-value and span caused
by 10° inclinations from the position(s) specified by the manufacturer shall be measured and
recorded in per cent of output span.
Four measurements shall be made with tilt applied in two planes at right angles to each other.
Where a 10° inclination is excessive due to the design of the DUT, the maximum inclination
specified by the manufacturer shall be used.
10 Over-range
This test shall be carried out by measuring any residual changes in lower range-value and span
which result from over-ranging the input by 50 % at the minimum and maximum span settings if
not otherwise specified by the manufacturer.
The input shall be increased gradually from the lower range-value to the over-range selected
for the test.
After the over-range has been applied for 1 min, the input shall be reduced to the nominal
lower range-value.
After a further 5 min have elapsed, the lower range-value and the span shall be determined in
per cent of output span.
61298-3 © IEC:1998 – 27 –
If the DUT is to be tested for over-range effect in both directions, as with differential measuring
devices and devices whose input may be both below the lower range-value and above the
upper range-value, it shall be tested as described above, first over-ranging above the upper
range-value, and then over-ranging below the lower range-value.
Any changes of lower range-value and span determined after over-ranging in each direction
shall be recorded.
NOTE – If over-ranging produces significant thermal effects, the duration of application should be increased
accordingly.
11 Output load effects
The purpose of this test is to determine any effects on the output signal when the output load is
varied.
11.1 Electrical output
To determine any effect on an electrical output signal, the load resistance shall be varied from
the minimum to the maximum value specified by the manufacturer. Any changes in lower
range-value and span caused by the variations shall be expressed as a percentage of the
output span. The output voltage drop at the DUT at the upper range value shall also be noted
when the DUT is a two-wire transmitter. Consideration should be given to the effect of
connecting capacitive or inductive loads.
11.2 Pneumatic output
This test shall be carried out as specified in 6.6 of IEC 61298-2.
12 Power supply effects
12.1 Supply voltage and frequency variations
For two-wire transmitters, reference should be made to 11.1 of this standard. For electrical
devices except two-wire transmitters, the test shall be carried out first setting the values of the
lower range and span at nominal supply voltage and frequency, then noting the changes of
these values, with the same values of input, caused by the following supply voltage and
frequency variations.
Voltage
a) Nominal value.
b) Nominal value +10 % for a.c. supplies, or nominal value +20 % for d.c. supplies, or the
manufacturer's limit if higher.
c) Nominal value –15 % for a.c. or d.c. supplies or the manufacturer's limit if less.
Frequency
a) Nominal value.
b) Nominal value +2 % or the manufacturer's limit if lower.
c) Nominal value –10 % or the manufacturer's limit if higher.

61298-3 © IEC:1998 – 29 –
Each value of voltage shall be combined with each value of frequency so that the result will be
nine sets of measurements for a.c. supplies or three sets of measurements for d.c. supplies.
Under low-voltage/low-frequency conditions, a check shall be made to establish that, with the
input at the 100 % of the span, the output does not limit below its upper range-value.
The voltage and frequency changes shall be made smoothly and gradually; the measurements
at 0 % and 100 % of output shall be made in steady-state conditions of voltage and frequency.
The changes at 0 % and 100 % of output shall be calculated and reported in per cent of span.
12.2 Transient supply voltage effects
The test shall be carried out by the following sets of measurements: where required, the test
shall be carried out as in 12.1 but with nominal frequency only. The effect of step changes (rise
time less than 1 ms) in voltage of +10 % for a.c. supplies (but 20 % for d.c. supplies) and
–15 % from nominal, applied for 10 ms, 100 ms, 1 000 ms and 10 000 ms shall be recorded
over time in terms of output span. The steps may be applied once only at the supply voltage
crossover point for a.c., but if applied randomly, 10 tests shall be carried out for each step.
12.3 Supply voltage depression
The output of the DUT shall be set at the upper range value, at the nominal supply voltage, and
then the supply voltage shall be reduced to 75 % of nominal value for a period of 5 s.
The rise time should be no faster than 100 ms to avoid transients.
The change in output shall be recorded over time and reported in per cent of ideal output span.
The circuit arrangement shown in figure 1 or an equivalent arrangement should be used.
Input
signal
DUT
source
Two-channel
recorder
Supply
Supply voltage
depressor
IEC  244/98
Figure 1 – Arrangement for supply voltage depression or interruption tests

61298-3 © IEC:1998 – 31 –
12.4 Short-term supply voltage interruptions
The purpose of this test is to determine not only the steady-state effects on the output, but also
the transient characteristics which may occur due to the interruption and recovery of the supply
voltage.
The input shall be held constant at 50 %.
The tests shall be arranged as in 12.2 and figure 1, but in this case, for d.c.-powered devices,
the tests shall be made with interruptions of 5 ms, 20 ms, 100 ms, 200 ms and 500 ms.
For a.c.-powered devices the interruptions shall occur at the crossover point and shall be for 1,
5, 10 and 25 cycles duration.
Alternatively, the test can be carried out be applying at least 10 random interruptions of each
duration.
Corcerning devices with threshold outputs, such as “alarms”, tests shall be applied in the same
way in order to assess the conditions influencing their performances, the alarm or commutation
level having been set at 10 % above and below the output threshold.
The following values shall be recorded:
– the maximum transient negative and positive change in output as a percentage of the output
span;
– the time taken for the output to reach 99 % of its steady-state value following reapplication
of power;
– any permanent change in output as a percentage of the output span.
12.5 Fast transient/burst immunity requirements
This test is required only for devices with electrical input/output or electrical power supply.
This test shall be carried out in accordance with the requirements of IEC 61000-4-4, at a
severity level specified by the manufacturer. The high-frequency bursts are to be coupled by a
capacitive clamp, first to all the electrical input signals at the same time, and subsequently to
all the output signals at the same time.
NOTE – In industrial process environments, only test voltages of 1 kV or more are of interest.
The input shall be held constant at 50 %.
The supply lines shall be protected by a suitable suppression filter, consisting at least of a
choke of 500 μH capable of carrying the line current.
During the tests, any changes in output due to the transients shall be recorded with a high-
speed device to obtain a permanent record of any effects of the transients.
The results shall be reported as a percentage of the output span for a given test level in kV.
NOTE – Care should be taken that the recording devices are not themselves directly affected by the voltage spike
applied to the DUT.
A similar test shall be carried out on the electrical power supply to the device, by means of a
coupling network defined in IEC 61000-4-4.

61298-3 © IEC:1998 – 33 –
12.6 Surge immunity requirements
This test is required only for devices with electrical power supplied.
The input levels shall be held at a value which produces 50 % output signal.
The test shall be carried out in accordance with the requirements of IEC 61000-4-5, at a
severity level specified by the manufacturer.
The high energy pulses are induced by means of a coupling network defined in IEC 61000-4-5.
NOTE – In industrial environments, only test voltages of 1 kV or more (symmetric direct coupling) or 2 kV
(asymmetric direct coupling) are of interest. The source impedance of the generator should be 42 Ω.
During the tests, any changes due to the surge voltages on the power supply are to be
recorded, as well as any damage caused to the device or the rupture of any fuse.
12.7 Reverse supply voltage protection (d.c. devices)
Unless the manufacturer states that damage will occur as a result of this test, the maximum
allowed supply voltage shall be applied in reverse.
Any malfunction or change in lower range value or span shall be noted.
12.8 Supply pressure variations
The test shall be carried out first checking the values of the lower range and span at nominal
supply pressure (pneumatic), then noting the eventual changes of these figures, with the same
values of input, caused by the following supply pressure variations:
a) +10 % of the nominal value or the manufacturer's limit;
b) –15 % of the nominal value or the manufacturer's limit.
The pressure changes shall be made smoothly and gradually; the measurements at 0 % and
100 % of output shall be made in the steady-state condition.
The change at 0 % and 100 % of the output shall be calculated and reported as a percentage
of the output span.
12.9 Supply pressure interruptions
The input shall be held constant at 100 % (or at 90 % if output limiting occurs).
The interruption test shall be conducted by shutting off the supply pressure (pneumatic) to the
DUT for 1 min.
When the supply pressure to the device is reapplied, it shall not be allowed to vary by more
than the reference tolerance. Any changes in output and settling time shall be reported.

61298-3 © IEC:1998 – 35 –
13 Electrical interference
13.1 Common mode interference
The purpose of this test is to determine the effect on the output due to extraneous voltages
applied between the input and output terminals in turn and earth.
This test is only applicable to devices with terminals which are isolated from earth.
It shall be carried out by measurement of the changes in lower range value and span caused
by the superposition of an a.c. signal of 250 V r.m.s. at mains frequency between earth and
each input and output terminal in turn. If the manufacturer specifies a value less than 250 V,
then this lower value shall be used instead. A 10 kW resistor shall be connected in series with
the interference.
The phase of the interfering signal shall be varied over 360° with respect to the phase of the
supply, so that the maximum effects of the influence quantity are revealed.
The test shall then be repeated using a d.c. voltage.
A potential of 50 V d.c. or 1 000 time the input span, whichever is less, shall be used, both
positive and negative potentials being applied. If the manufacturer specifies a value less
than 50 V, this lower value shall be used.
During the common mode interference tests, the DUT shall be supplied from an input signal
source which is not affected by the common mode signal.
For current-input devices, the signal source shall be a current source with not less than 10 μF
capacitance connected across its output terminals.
For voltage-input devices, the signal source shall be a voltage source with an output
impedance no greater than 100 Ω at mains frequency.
The change of output at 0 % and 100 % (or 10 % and 90 %) input shall be noted and reported
as a percentage of output span.
NOTE – Common mode interference tests are also commonly conducted by connecting the test signal to both input
or both output terminals simultaneously. If the impedance between terminals is low relative to impedance to earth,
both test methods yield equivalent results. The method described above has been chosen to promote consistency
of method and results among testing agencies for a wide range of devices.

61298-3 © IEC:1998 – 37 –
A suitable test set-up is shown in figure 2.
Oscilloscope
Input source
DUT
Device
Load Digital voltmeter
enclosure
earth
50 Hz/60 Hz alternating
voltage unit adjustable for
V
phase and amplitude
IEC  245/98
Common mode a.c. generator
Oscilloscope
Input source
DUT
Device
enclosure
Digital voltmeter
Load
earth
DC voltage unit
V
adjustable
Common mode d.c. gen
...