oSIST prEN 4914-100:2026

SLOVENSKI STANDARD
01-januar-2026
Aeronavtika - Preskusni postopki za elektromehanske releje tipa vse ali nič
Aerospace series - Test procedures for electromechanical all-or-nothing relays
Luft- und Raumfahrt - Prüfverfahren für elektromechanische Schaltrelais
Ta slovenski standard je istoveten z: prEN 4914-100
ICS:
29.120.70 Releji Relays
49.060 Letalska in vesoljska Aerospace electric
električna oprema in sistemi equipment and systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2025
ICS 49.060
English Version
Aerospace series - Test procedures for electromechanical
all-or-nothing relays
Luft- und Raumfahrt - Prüfverfahren für
elektromechanische Schaltrelais
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee ASD-
STAN.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 4914-100:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Test and measurement procedures . 12
4.1 General. 12
4.2 Alternative test methods . 12
4.3 Precision of measurement . 12
4.4 Requirements in Detail Specifications . 12
4.5 Standard conditions for testing . 12
4.6 Mounting styles and terminal type . 13
4.7 Electric wiring . 18
4.8 Functional characteristics . 18
4.8.1 Visual inspection and check of dimensions . 18
4.8.2 Weighing . 18
4.8.3 Relay coil properties . 18
4.8.4 Dielectric test . 20
4.8.5 Impulse voltage test . 21
4.8.6 Insulation resistance . 21
4.8.7 Contact resistance (or voltage drop) . 21
4.8.8 Pick-up voltage . 25
4.8.9 Drop-out voltage . 26
4.8.10 Timing tests. 26
4.9 Mechanical tests . 30
4.9.1 General. 30
4.9.2 Vibration sinusoidal . 31
4.9.3 Vibration random . 31
4.9.4 Shock . 32
4.9.5 Acceleration . 32
4.10 Climatic and environmental tests . 32
4.10.1 Rapid change of temperature . 32
4.10.2 Salt mist . 32
4.10.3 Seal . 33
4.11 Electrical tests . 33
4.11.1 General. 33
4.11.2 Coil current for AC relays . 33
4.11.3 Electromagnetic interference . 33
4.11.4 Outgoing interference voltage . 33
4.11.5 Incoming interference voltage . 34
4.11.6 Power input . 34
4.11.7 Voltage spike . 34
4.11.8 Radio Frequency Susceptibility (Radiated and Conducted) . 34
4.11.9 Lightning Induced Transient Susceptibility . 34
4.11.10 Actuating voltage at high temperature . 35
4.11.11 Voltage drop at low temperature . 35
4.12 Service life . 37
4.12.1 Coil life (duty cycle) . 37
4.12.2 Coil endurance . 39
4.12.3 Mechanical life (at reduced load) . 39
4.12.4 Overload (AC and DC) . 40
4.12.5 Circuit breaker compatibility . 40
4.12.6 Electrical service life — Inductive load . 42
4.12.7 Electrical service life — Motor load . 43
4.12.8 Electrical service life — Resistive load . 44
4.12.9 Electrical service life — Mixed load . 45
Bibliography . 47

European foreword
This document (prEN 4914-100:2025) has been prepared by ASD-STAN.
After enquiries and votes carried out in accordance with the rules of this Association, this document has
received the approval of the National Associations and the Official Services of the member countries of
ASD-STAN, prior to its presentation to CEN.
This document is currently submitted to the CEN Enquiry.
1 Scope
This document specifies the test procedures of electromechanical all-or-nothing relays for use in
aircraft electrical systems to EN 2282.
This document represents the aeronautical version of the standard EN 116000-3 from which it draws
inspiration.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 2678, Environmental tests for aircraft equipment — Insulation resistance and high voltage tests for
electrical equipment
IEC 60068-2-7, Basic environmental testing procedures. Part 2-7: Tests — Test Ga: Acceleration, steady
state
IEC 60068-2-11, Environmental testing — Part 2-11: Tests — Test Ka: Salt mist
IEC 60068-2-14, Environmental testing — Part 2-14: Tests — Test N: Change of temperature
IEC 60068-2-27, Environmental testing — Part 2-27: Tests — Test Ea and guidance: Shock
IEC 60255-27:2025, Measuring relays and protection equipment - Part 27: Product safety requirements
EN 4915-001, Aerospace series — Hermetically sealed relays 2 PDT, 4 PDT and 6 PDT — Part 1:
Technical specification
ISO 7137, Aircraft — Environmental conditions and test procedures for airborne equipment
MIL-STD-202-204, Method 204, Vibration, high frequency
MIL-STD-202-214, Method 214, Random vibration
MIL-PRF-83536 G, Relays, electromagnetic, established reliability, 25 Amperes and below, general
specification for
RTCA DO-160 G:2010, Environmental conditions and test procedures for airborne equipment
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
electromechanical relay
electrical relay in which the designed response is developed by the relative movement of mechanical
elements under the action of a current in the input circuit(s)

This document is currently under development.
Published by Department of Defense (DoD), available at: https://assist.dla.mil/online/start/.
Published by RTCA, available at: https://www.rtca.org/. Published conjointly by European Organization for Civil
Aviation Equipment (EUROCAE), as EUROCAE ED-14, available at: https://eurocae.net/.
3.2
all-or-nothing relay (or switching relay)
electrical relay which is intended to be energized by a quantity, whose value is either:
— higher than that at which it operates;
— or lower than that at which it releases
Note 1 to entry: The adjective “all-or-nothing” can be deleted when no ambiguity may occur.
3.3
monostable relay
electrical relay which, having responded to an input energizing quantity and having changed its
condition, returns to its previous condition when the quantity is removed
3.4
bistable relay
electrical relay which, having responded to an input energizing quantity and having changed its
condition, remains in that condition after the quantity has been removed. A further appropriate
energization is required to make it change over to the previous condition/situation
3.5
polarized relay
relay, change of condition of which depends upon the direction of its input energizing quantity
3.6
non-polarized relay
relay, change of condition of which does not depend upon the direction of its input energizing quantity
3.7
release condition
specified condition of the relay when it is not energized
3.8
release condition
specified condition, as declared by the manufacturer
3.9
operate condition
specified condition of the relay when it is energized in a specified manner
3.10
operate condition
the condition other than the release condition as declared by the manufacturer
3.11
to operate
relay operates when it changes from its release condition to its operate condition
3.12
to release
relay releases when it changes from its operate condition to its release condition
3.13
to change over
relay changes over when it operates or releases
3.14
to cycle
relay cycles when it operates and then releases, or vice versa
3.15
make contact

contact which is closed when the relay is in its operate condition and which is opened when the relay is
in its release condition
3.16
break contact

contact which is opened when the relay is in its operate condition and which is closed when the relay is
in its release condition
3.17
change-over contact
combination of two contact circuits including three contact members, one of them being common to the
two contact circuits. When one of these contact circuits is open, the other is closed and vice versa
3.18
change-over make-before-break contact

one contact circuit of which makes before the other breaks
3.19
change-over break-before-make contact

one contact circuit of which breaks before the other makes
Note 1 to entry: Prefixes for the values applicable to relays.
Note 2 to entry: Values may be defined as rated, actual (“just”), test (“must”) or characteristic value and identified
as such by using one of these words as a prefix. The prefixes are also applicable to timing values.
3.20
rated value
value of a quantity assigned, generally by a manufacturer, for a specified operating condition of a relay
3.21
actual (“just”) value
value of a quantity determined by measurement on a single relay when it just performs a specified
function
3.22
test (“must”) value
value of a quantity with which, during tests, the relay is required to perform or not to perform a
specified function
3.23
characteristic value
value of a quantity with which, throughout its lifetime or a specified number of cycles, the relay is
required to comply with a specified requirement
3.24
energizing quantity
electrical quantity (either current or voltage or power) which alone, or in combination with other such
quantities applied to a relay under specified conditions, enables it to fulfil its purpose
3.25
operative range of an energizing quantity
range of values of an energizing quantity for which the relay under specified conditions is able to
perform its intended function(s) according to the specified requirements
3.26
non-operate value
value of the energizing quantity at which a relay does not operate
3.27
operate value
value of the energizing quantity at which a relay operates
3.28
non-release value (hold value)
value of the energizing quantity at which a relay does not release
3.29
release value
value of the energizing quantity at which a relay release
3.30
non-revert value

value of the energizing quantity at which the relay, being in an operate condition, does not release by
increasing the value of this energizing quantity
3.31
non-revert-reverse value

the value of the energizing quantity at which the relay, being in a release condition, does not operate by
increasing the value of this energizing quantity
3.32
reverse polarity value
value of the energizing quantity of reverse polarity at which a polarized monostable relay does not
operate
3.33
contact current
current which a relay contact carries before opening or after closing
3.34
contact voltage
voltage between the contact members before dosing or after opening
3.35
limiting continuous current
highest value of the current (RMS if AC), which a previously closed contact circuit is capable of carrying
continuously
3.36
contact noise
spurious voltage which appears across the terminals of a closed contact
3.37
contact tip; contact point
conductive part of a contact member designed to co-act with another to close the contact circuit
3.38
contact gap
gap between the contact tips (points) under specified conditions when the contact circuit is open
3.39
contact force
force which two contact tips (points) exert against each other in the closed position under specified
conditions
Note 1 to entry: Such as:
— Terms relating to times
— The operate time, release time, transfer time and bridging time, as defined hereunder, do not
include bounce times. The operate time covers the closing time of a make contact and the opening time of a
break contact. The release time covers the opening time of a make contact and the closing time of a break
contact.
3.40
operate time
relay which is in the release condition the time interval between the instant
Note 1 to entry: A specified value of the input energizing value is applied and the first closing (or opening) of the
contact circuit
Note2 to entry: When the relay has several output circuits, the timing should be taken for the last to break
and/or last to make, unless otherwise specified.
3.41
release time
relay which is in the operate condition the time interval between the instant.
Note 1 to entry: A specified value of the input energizing value is removed and the first opening (or closing) of the
contact circuit
Note 2 to entry: When the relay has several output circuits, the timing should be taken for the last to break
and/or last to make, unless otherwise specified.
3.42
transfer time

time interval during which both contact circuits are open
3.43
bridging time

time interval during which both contact circuits are closed
3.44
bounce time
contact which is closing (opening) its circuit, the time interval between the instant when the contact
circuit first closes (opens) and the instant when the circuit is finally closed (opened)
3.45
time to stable closed (open) condition; stabilization time
time interval between the instant when a specified value of the input energizing quantity is applied and
the instant when a contact is closed (open) and fulfils specified requirements
3.46
minimum time of operate energization
minimum duration of application of rated operate value required to ensure that the contact circuit
fulfils specified requirements
3.47
contact time difference

difference between the maximum value of the operate (release) time and the minimum value of the
operate (release) time
3.48
coil transient suppression device
device connected to the relay coil to limit its back e.m.f. to a prescribed value
Characteristics for operating, release and bounce times:

Key
1 switch closure 7 contact break bounce duration
2 operating time 8 switch opening
3 transfer time 9 release time
4 operating time characteristic 10 release time characteristic
5 dynamic contact resistance effect 11 contact make bounce duration
6 contact closing bounce duration (make bounce)
Figure 1
Key
1 Switch 4 Self-synchronous oscilloscope
2 To oscilloscope trigger 5 Relay coil
3 No contact 6 Control voltage
Figure 2
Key
1 Maker opens 4 Start of armature movement
2 Breaker closes 5 Limit voltage
3 End of armature movement 6 Switch opens
Figure 3 — Outgoing interference voltage (Typical curve)
4 Test and measurement procedures
4.1 General
Specifications (e.g. Relays Detail Specifications) for quality assessment purposes shall contain tables
showing the tests to be made, which measurements are to be made before and after each test or
subgroup of tests, and the sequence in which they shall be carried out.
4.2 Alternative test methods
Measurements shall preferably be carried out by using the methods specified. Any other method giving
equivalent results may be used except in case of dispute.
NOTE “equivalent” means that the value of the characteristic established by such other method falls within
the specified limits when measured by the specified method.
4.3 Precision of measurement
The limits quoted in Detail Specifications are true values. Measurement inaccuracies shall be taken into
account when evaluating the results. Usual precautions should be taken to reduce measurement errors
to a minimum.
4.4 Requirements in Detail Specifications
If the requirements of this specification are not entirely suitable (either for technical reasons or because
of a special application), the Detail Specification shall set out clearly the revised requirements.
4.5 Standard conditions for testing
Unless otherwise specified, all tests shall be carried out under the standard atmospheric and conditions
described below:
Temperature 22 ± 3 °C
Relative humidity 45 to 70 %
Air pressure 96 ± 10 kPa
960 ± 100 mbar
Before testing, the relays shall be subjected to the standard atmospheric conditions for a time sufficient
to allow them to reach thermal equilibrium.
Unless otherwise specified, the terms AC voltage and current indicate RMS values throughout this
specification.
Any value to be assigned to quantities as defined in this specification will relate to specified conditions
which are within the intended conditions of use of a relay, and different values may apply to steady-
state and dynamic operation.
The operating error in voltage or current shall not exceed 5 % for a load twice that specified for the test.
The peak-to-peak periodic and random deviations of the output of a DC supply shall not exceed 1 %.
The operating error in frequency of an AC supply shall not exceed 2 %, and the form factor shall be
within 0,95 and 1,25.
The following shall be earthed as applicable: the negative side of the DC power supply, one side of the
single-phase AC power supply, or the neutral of the three-phase AC power supply.
The earthed side of the power supply shall be connected to: one terminal each of one or more coils of
the relay under test, and one terminal of each of the loads connected to the relay under test.
Contacts and/or other parts shall not be cleaned or adjusted prior to submission to a test, unless
otherwise prescribed in the Detail Specification.
Where mounting is required for a particular test, the relay shall be mounted in accordance with the
specified fixing instructions.
4.6 Mounting styles and terminal type
The table below lists the different possible variants for qualification testing.
Table 1 — Relays variants for qualification testing
Horizontal
Horizontal Horizontal Vertical
Without (Can bracket with
bracket with bracket with bracket with
without spacer and
UNC or metric mounting mounting
fixation) mounting
captive screws holes holes
holes
Tin plated pins
(including Variant 01 Variant 02 Variant 02 Variant 03 Variant 02
short pin)
Variant not
Solder hooks Variant 04 Variant 04 Variant 05 Variant 04
recommended
Gold tin plated Variant not Variant not
Variant 06 Variant 06 Variant 06
pins recommended recommended
Bent tin plated Variant not Variant not Variant not
Variant 07 Variant 08
pins recommended recommended recommended
A test procedure as described below shall be implemented for the different relay variants:
The assemblies below are given for information only. The additional elements are optional, but the
installation shall avoid generating amplification on the relays.
Variant 01: Relay without fixation and with tin plated pins soldered on a printed circuit board and fixed
on a mechanical frame.
Figure 4 — Illustration of variant 01

Variant 02: Relay with horizontal brackets and with tin plated pins soldered on a printed circuit board
and fixed on a mechanical frame.
Figure 5 — Illustration of variant 02
Variant 03: Relay with vertical brackets and with tin plated pins soldered on a printed circuit board and
fixed on a mechanical frame.
Figure 6 — Illustration of variant 03

Variant 04: Relay with horizontal brackets and with solder hooks and fixed on a mechanical frame.
Figure 7 — Illustration of variant 04
Variant 05: Relay with vertical brackets and with solder hooks and fixed on a mechanical frame.
Figure 8 — Illustration of variant 05

Variant 06: Relay with horizontal brackets and with gold tin plated pins and fixed on a relay socket.
Figure 9 — Illustration of variant 06
NOTE For this variant, the relay is to be glued on the printed circuit board.
Variant 07: Relay without fixation and with bent tin plated pins soldered on a printed circuit board and
fixed on a mechanical frame.
Figure 10 — Illustration of variant 07

Variant 08: Relay vertical brackets fixation and with bent tin plated pins soldered on a printed circuit
board and fixed on a mechanical frame.
Figure 11 — Illustration of variant 08
4.7 Electric wiring
For qualification testing of relays with plug -socket terminals or solder hook terminals, wiring suitable
for the contact loads specified shall be used.
4.8 Functional characteristics
4.8.1 Visual inspection and check of dimensions
The relays (and their accessories, if applicable) shall be checked for conformity to the outline drawings,
including creepage distances and clearances, prescribed in the Detail Specification.
Unless otherwise prescribed in the Detail Specification, visual inspection shall be performed under
normal factory lighting and visual conditions.
External inspection and check of key dimensions shall be carried out as non-destructive tests.
Visual inspection shall include:
— correctness of marking;
— correctness of terminal identification;
— correct housing;
— absence of physical defects, as prescribed in the Detail Specification.
The condition, workmanship and finish shall be satisfactory as determined by visual inspection.
4.8.2 Weighing
Where prescribed in the Detail Specification, the relay shall be weighed.
Conditions to be prescribed in the Detail Specification:
— mass of the relay, and tolerances.
4.8.3 Relay coil properties
4.8.3.1 Coil resistance
Purpose: To ensure that the DC resistance of the relay coil(s) is within the specified limits.
Procedure: The resistance shall be measured between the terminals of the relay. The method shall
involve negligible temperature rise.
Conditions to be prescribed in the Detail Specification:
— coil resistance limits;
— temperature coefficient of the wire material, if other than electrolytic copper;
— any special precautions due to the presence of resistors, diodes, etc. in the coil circuit.
Alternative test methods: MIL-STD-202-303 or an automatic relays tester
4.8.3.2 Coil inductance
Non-applicable.
Purpose: To ensure that the inductance of the relay coil(s) is within the specified limits.
Procedure: The coil inductance shall be measured in the non-energized and in the rated energized
condition of the relay. The relay shall be mounted with no adjacent metal parts.
Unless otherwise prescribed in the Detail Specification, the AC voltage applied for measurement shall be
sinusoidal at a frequency equal to the nominal frequency of the energizing quantity or for DC relays as
prescribed in the Detail Specification.
The measurement on inductance, by determining the time constant, is a permissible alternative.
When DC energization is to be superimposed in the winding during measurement, adequate means for
isolation of the AC and DC circuits shall be provided.
4.8.3.3 Coil impedance and burden
Non-applicable.
Purpose: To ensure that the impedance of the relay coil(s) is within the specified limits.
Procedure: The relay shall be mounted with no adjacent metal parts.
Method 1: The coil impedance shall be measured in the non-energized and the rated energized
condition of the relay.
Unless otherwise prescribed in the Detail Specification, the AC voltage applied for measurement shall be
sinusoidal at a frequency equal to the nominal frequency of the energizing quantity or for DC relays as
prescribed in the Detail Specification.
When DC energization is to be superimposed in the winding during measurement, adequate means for
isolation of the AC and DC circuits shall be provided.
Method 2: The burden shall be measured in the rated energized condition of the relay or, for a relay the
burden of which varies with the position of its moving parts, in the energized conditions as prescribed
in the Detail Specification.
4.8.3.4 Coil transient suppression test
Purpose: To verify that the back-EMF. generated by the relay coil is not greater than the maximum
specified induced transient voltage.
Procedure: The relay shall be connected to a test-circuit as shown in Figure 12 and energized at rated
coil voltage. The switching relay is operated from a source voltage independent of the relay energizing
source. The oscilloscope should have a rise time of 0,02 µs or less. The time deflection scale of the
oscilloscope shall be set at 0,5 ms/cm to 1 ms/cm. It is important that the energizing source is a low
impedance source with no limiting resistor or potentiometer used to regulate the line voltage.
The switching relay shall be closed for a minimum of 10 times the operate time of the relay under test
to allow the oscilloscope and circuit network to stabilize and then opened to obtain the induced voltage
deflection trace. The cycling rate of the relay should be 10 ± 2 Hz and the duty factor 50 % unless
otherwise specified in the Detail Specification. The reading shall be observed on the oscilloscope. The
magnitude of the induced transient voltage shall be noted. A typical oscilloscope reading is presented
below, in Figure 12:
Key
1 switching relay contact opens b start armature movement
2 test relay contact opens (break contact) c end armature movement
3 test relay contact closes (break contact)
Figure 12
Conditions to be prescribed in the Detail Specification:
— rated coil voltage;
— cycling rate if different from 10 ± 2 Hz;
— duty factor if different from 50 %;
— number of consecutive readings if different from 3;
— ambient temperature if different from 25 ± 10 °C;
— limits for back-EMF
Alternative test methods: MIL-STD-202-303 or an automatic relays tester
4.8.4 Dielectric test
Procedure: This test shall be carried out in accordance with the dielectric test of IEC 60255-27 or
ISO 2678. The test voltage shall be applied between all terminals which are insulated from each other
and between all terminals and the housing.
The test shall be performed both with the relay de-energized and energized.
The test duration shall be as follows:
— for batch acceptance and acceptance testing: 0.3 s to 5 s:
— for certification testing: 1 min.
NOTE During the test in the de-energized state the coil terminals are to be connected to each other.
The relay shall not be damaged during the test.
The leakage current shall not exceed 1 mA.
Test criteria: The dielectric strength of the relay shall comply with the values specified in the product
standards.
The test conditions and requirements are described in the Detail Specification.
Alternative test methods: MIL-STD-202-301 or an automatic relays tester
4.8.5 Impulse voltage test
Non-applicable.
Procedure: This test shall be carried out in accordance with the impulse voltage test of
IEC 60255-27:2025 (Clause 8), and shall be applied to the parts of the relay following the detailed
requirements specified in the Detail Specification. A flashover is a criterion of failure only if it causes
permanent damage; after application on the impulses, the relay shall comply with the final
measurements prescribed in the Detail Specification.
4.8.6 Insulation resistance
Procedure: The insulation resistance shall be measured between all terminals which are insulated from
each other and also between all terminals and the housing. This test shall be carried out in accordance
with the insulation resistance measurement procedure of IEC 60255-27:2025 (Clause 7) or ISO 2678.
The test shall be performed both with the relay energized and de-energized.
The test voltage shall be 500 VDC.
The test duration shall be as follows:
— for batch acceptance and acceptance testing: the specified insulation resistance shall be reached
within 10 s;
— the insulation resistance measurements shall be made immediately after a 2-min period of
uninterrupted test voltage application. However, if the instrument reading indicates that an
insulation resistance meets the specified limit, and is steady or increasing, the test may be
terminated before the end of the specified period.
The test conditions and requirements are described in the Detail Specification.
Alternative test methods: MIL-STD-202-302 or an automatic relays tester
4.8.7 Contact resistance (or voltage drop)
Procedure: The resistance shall be measured using a 4-terminal bridge, by the voltmeter-ammeter
method, or, particularly for dynamic tests, using automatic monitoring equipment. Measurements shall
be made with alternating voltage at a frequency of 0,8 kHz to 2 kHz, or as prescribed in the Detail
Specification. If DC is prescribed, the resistance shall be measured as described in the Detail
Specification.
One measurement shall be made per cycle.
The type of measurement shall be as prescribed in the Detail Specification, and be selected from the
following:
Static contact resistance measurement denotes that, for each measurement, the contacts remain closed
for an interval sufficient to allow all transients to decay. Three test cycles shall be made.
Dynamic contact resistance measurement denotes that the relay coil is energized by a square wave, the
frequency being as prescribed in the Detail Specification. A specified number of cycles shall be made,
and each of the cycles shall be monitored. Monitoring shall start after the contact has reached stable
closed condition, or after at least 30 % of the closed part of each cycle has elapsed, whichever is later.
Any irregularity in contact-circuit resistance not exceeding a duration of 10 ps shall be ignored, unless
another value is prescribed in the Detail Specification.
The coil shall be energized at the rated energization, or as specified in the Detail Specification. There
shall be no preconditioning cycle prior to the measurement.
During endurance test, checking of contact resistance can be carried out by another method, for
example by checking the voltage drop across the tested contact with the load current flowing through
the contact, unless otherwise stated in the Detail Specification.
Alternative test methods: MIL-STD-202-307 or an automatic relays tester
The test conditions and requirements are described in the Detail Specification.
Electricals tests
Purpose: To ensure that the relay performs satisfactorily at its specified energization values.
Procedure: Table below sets out the applicable values and the significance of the functional tests,
referring to Figures 1 to 5 which give typical examples.
Testing is made by attributes, and shall be made in the order given below, or in the order prescribed in
the Detail Specification.
Testing by variables: No requirements at present.
The magnetic preconditioning shall be applied, and the orientation of the relay shall take account of any
external magnetic field.
When proceeding from one step to the next, the characteristics of the energizing quantity shall be as
prescribed in the Detail Specification. The corresponding function of the relay shall be checked by visual
inspection or, if this is impracticable, by monitoring the contacts.
Conditions to be prescribed in the Detail Specification:
— energization values and values for preconditioning, as required, and their polarity;
— order of steps, if different from above;
— application of consecutive pulses, instead of stepwise changes, if applicable;
— time between the steps, or device to be used to perform them, if a more precise specification is
required;
— application of the test to new relays or after a specified number of cycles;
— magnetic orientation, if required;
— details of monitoring, if required.
Table 2 — Energization values and corresponding functions
Applied value The relay shall Applicable to
Diagram
code
A non-operate value not operate all types
B operate value operate all types
C rated value remain operated all types
D non-revert value remain operated polarized
e/g non-release value not release all types
f/h release value release all types
I reverse rated value remain non-operated bistable polarized
J reverse non-revert value not operate bistable polarized
K reverse polarity value not operate monostable polarized
X preconditioning value be preconditioned all if required
Y setting value be set in required position all if required
Z reverse setting value be set in required position all if required
NOTE The diagram codes refer to Figures 13 to 17.

Figure 13 — Monostable non-polarized relay
Figure 14 — Monostable relay polarized by diode

Figure 15 — Monostable polarized relay with magnetic biasing
Figure 16 — Bistable non-polarized relay

Figure 17 — Bistable polarized relay (example)
4.8.8 Pick-up voltage
Test procedure: The coil shall be left in a de-energized condition for 30 min before starting the test.
The rated voltage shall be applied to the coil, then reduced to zero and gradually increased until the
relay pulls in.
The contacts shall not change their switching position when the voltage is increased from the pick-up
voltage to the maximum operating voltage.
A suitable relay shall be used to determine the position of the contacts.
For qualification tests, the relay shall be tested in each of the three axes which are perpendicular to each
other.
Test criteria: The relay shall be energized at the rated voltages specified in the product standards.
An automatic relays tester shall be used to perform the test.
4.8.9 Drop-out voltage
Test procedure: The coil shall be left in a de-energized condition for 30
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