ISO 16750-2:2012

INTERNATIONAL ISO
STANDARD 16750-2
Fourth edition
2012-11-01
Road vehicles — Environmental
conditions and testing for electrical
and electronic equipment —
Part 2:
Electrical loads
Véhicules routiers — Spécifications d’environnement et essais de
l’équipement électrique et électronique —
Partie 2: Contraintes électriques
Reference number
©
ISO 2012
© ISO 2012
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Published in Switzerland
ii © ISO 2012 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test and requirements . 1
4.1 General . 1
4.2 Direct current supply voltage . 2
4.3 Overvoltage . 2
4.4 Superimposed alternating voltage . 3
4.5 Slow decrease and increase of supply voltage . 6
4.6 Discontinuities in supply voltage . 6
4.7 Reversed voltage .13
4.8 Ground reference and supply offset.14
4.9 Open circuit tests .14
4.10 Short circuit protection .15
4.11 Withstand voltage .16
4.12 Insulation resistance .17
4.13 Electromagnetic compatibility .17
5 Documentation .17
Annex A (normative) Test load dump pulse generator verification procedure.18
Annex B (informative) Origin of load dump pulse in road vehicles electrical systems .19
Bibliography .20
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 16750-2 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3, Electric
and electronic equipment.
This fourth edition cancels and replaces the third edition (ISO 16750-2:2010), which has been
technically revised.
ISO 16750 consists of the following parts, under the general title Road vehicles — Environmental conditions
and testing for electrical and electronic equipment:
— Part 1: General
— Part 2: Electrical loads
— Part 3: Mechanical loads
— Part 4: Climatic loads
— Part 5: Chemical loads
iv © ISO 2012 – All rights reserved

INTERNATIONAL STANDARD ISO 16750-2:2012(E)
Road vehicles — Environmental conditions and testing for
electrical and electronic equipment —
Part 2:
Electrical loads
1 Scope
This part of ISO 16750 applies to electric and electronic systems/components for road vehicles. This
part of ISO 16750 describes the potential environmental stresses and specifies tests and requirements
recommended for the specific mounting location on/in the road vehicle.
This part of ISO 16750 describes the electrical loads. Electromagnetic compatibility (EMC) is not covered
by this part of ISO 16750. Electrical loads are independent from the mounting location, but can vary due
to the electrical resistance in the vehicle wiring harness and connection system.
2 Normative references
The following referenced documents are indispensable for the application 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 8820 (all parts), Road vehicles — Fuse-links
ISO 16750-1, Road vehicles — Environmental conditions and testing for electrical and electronic equipment —
Part 1: General
ISO 16750-4, Road vehicles — Environmental conditions and testing for electrical and electronic
equipment — Part 4: Climatic loads
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16750-1 apply.
4 Test and requirements
4.1 General
If not otherwise specified, the following tolerances shall apply:
— frequency and time: ±5 %;
— voltages: ±0,2 V;
— resistance: ±10 %;
All voltage curves are shown without load.
If not otherwise specified, measure all voltages at the relevant terminals of the device under test (DUT).
4.2 Direct current supply voltage
4.2.1 Purpose
The purpose of this test is to verify equipment functionality at minimum and maximum supply voltage.
4.2.2 Test method
Set the supply voltage as specified in Table 1 or Table 2 to all relevant inputs of the DUT. Operating
modes are specified in ISO 16750-1.
The voltages listed in Table 1 or Table 2 are relevant within the operating temperature range as specified
in ISO 16750-4, without time limits.
Table 1 — Supply voltage for system devices with 12 V nominal voltage
Minimum supply voltage, U Maximum supply voltage, U
Smin Smax
Code
V V
A 6 16
B 8 16
C 9 16
D 10,5 16
Table 2 — Supply voltage for system devices with 24 V nominal voltage
Minimum supply voltage, U Maximum supply voltage, U
Smin Smax
Code
V V
E 10 32
F 16 32
G 22 32
H 18 32
4.2.3 Requirements
All DUT functions shall remain class A as defined in ISO 16750-1 when tested in the supply voltage
ranges given in Table 1 or Table 2, respectively.
4.3 Overvoltage
4.3.1 Systems with 12 V nominal voltage
4.3.1.1 Test at a temperature of T − 20 °C
max
4.3.1.1.1 Purpose
This test simulates the condition where the generator regulator fails, so that the output voltage of the
generator rises above normal values.
4.3.1.1.2 Test method
Heat the DUT in a hot air oven to a temperature that is 20 °C below the maximum operating temperature,
T . Apply a voltage of 18 V for 60 min to all relevant inputs of the DUT.
max
2 © ISO 2012 – All rights reserved

4.3.1.1.3 Requirement
The functional status for the DUT shall be minimum class C as defined in ISO 16750-1. Functional status
shall be class A where more stringent requirements are necessary.
4.3.1.2 Test at room temperature
4.3.1.2.1 Purpose
This test simulates a jump start.
4.3.1.2.2 Test method
Ensure that the DUT has stabilized at room temperature. Apply a voltage of 24 V for (60 ± 6) s to all
relevant inputs of the DUT.
4.3.1.2.3 Requirement
The functional status shall be minimum class D as defined in ISO 16750-1. Functional status shall be
class B where more stringent requirements are necessary.
4.3.2 Systems with 24 V nominal voltage
4.3.2.1 Purpose
This test simulates the condition where the generator regulator fails, so that the output voltage of the
generator rises above normal values.
4.3.2.2 Test at a temperature of T − 20 °C
max
Heat the DUT in a hot air oven to a temperature that is 20 °C below the maximum operating temperature,
T . Apply a voltage of 36 V for 60 min to all relevant inputs of the DUT.
max
4.3.2.3 Requirement
The functional status shall be minimum class C as defined in ISO 16750-1. Functional status shall be
class A where more stringent requirements are necessary.
4.4 Superimposed alternating voltage
4.4.1 Purpose
This test simulates a residual alternating current on the direct current supply.
4.4.2 Test method
Connect the DUT as shown in Figure 1. Apply the following test simultaneously to all applicable inputs
(connections) of the DUT; the severity level (1, 2, 3 or 4) shall be chosen in accordance with the application:
— maximum supply voltage, U (see Figure 2):
Smax
— 16 V for systems with nominal voltage, U , of 12 V;
N
— 32 V for systems with nominal voltage, U , of 24 V;
N
— a.c. voltage (sinusoidal):
— severity 1: peak to peak voltage, U , of 1 V, for U = 12 V and U = 24 V;
PP N N
— severity 2: peak to peak voltage, U , of 4 V, for U = 12 V and U = 24 V;
PP N N
— severity 3: peak to peak voltage, U , of 10 V, for U = 24 V only;
PP N
— severity 4: peak to peak voltage, U , of 2 V, for U = 12 V only;
PP N
— internal resistance of the power supply: 50 mΩ to 100 mΩ;
— frequency range (see Figure 3): 50 Hz to 25 kHz;
— type of frequency sweep (see Figure 3): triangular, logarithmic;
— sweep duration (see Figure 3): 120 s;
— number of sweeps: 5 (continuously).
Key
1 sweep generator
2 power supply unit capable of being modulated
3 DUT
4 positive
5 ground or return
Figure 1 — Test set-up to superimpose a.c. voltage on component power supply lines
4 © ISO 2012 – All rights reserved

Key
t time
U test voltage
U peak to peak voltage
PP
U maximum supply voltage
Smax
Figure 2 — Test voltage with superimposed sinusoidal a.c. voltage
Key
t time, in seconds
f frequency, logarithmic scale, in hertz
1 one cycle
Figure 3 — Frequency sweep
4.4.3 Requirement
The functional status shall be class A as defined in ISO 16750-1.
4.5 Slow decrease and increase of supply voltage
4.5.1 Purpose
This test simulates a gradual discharge and recharge of the battery.
4.5.2 Test method
Apply the following test simultaneously to all applicable inputs (connections) of the DUT.
Decrease the supply voltage from the minimum supply voltage, U , to 0 V, then increase it from 0 V to
Smin
U , applying a change rate of (0,5 ± 0,1) V/min linear, or in equal steps of not more than 25 mV.
Smin
4.5.3 Requirement
The functional status inside the supply voltage range (see Table 1 or Table 2) shall be as specified in
4.2.3. Outside that range, it shall be minimum class D as defined in ISO 16750-1. The functional status of
class C may be specified where more stringent requirements are necessary.
4.6 Discontinuities in supply voltage
4.6.1 Momentary drop in supply voltage
4.6.1.1 Purpose
This test simulates the effect when a conventional fuse element melts in another circuit.
4.6.1.2 Test method
Apply the test pulse (see Figures 4 and 5) simultaneously to all relevant inputs (connections) of the DUT.
The rise time and fall time shall be not more than 10 ms.
Key
t time, in seconds
U test voltage, in volts
U minimum supply voltage
Smin
Figure 4 — Short voltage drop for systems with 12 V nominal voltage
6 © ISO 2012 – All rights reserved

Key
t time, in seconds
U test voltage, in volts
U minimum supply voltage
Smin
Figure 5 — Short voltage drop for systems with 24 V nominal voltage
4.6.1.3 Requirement
The functional status shall be minimum class B as defined in ISO 16750-1. Reset is permitted upon agreement.
4.6.2 Reset behaviour at voltage drop
4.6.2.1 Purpose
This test verifies the reset behaviour of the DUT at different voltage drops. This test is applicable to
equipment with reset function, e.g. equipment containing microcontroller(s).
4.6.2.2 Test
Apply the test pulse simultaneously in Figure 6 to all relevant inputs (connections) and check the reset
behaviour of the DUT.
Decrease the supply voltage by 5 % from the minimum supply voltage, U , to 0,95U . Hold this
Smin Smin
voltage for 5 s. Raise the voltage to U . Hold U for at least 10 s and perform a functional test. Then
Smin Smin
decrease the voltage to 0,9U . Continue with steps of 5 % of U , as shown in Figure 6, until the
Smin Smin
lower value has reached 0 V. Then raise the voltage to U again.
Smin
Key
t time, in seconds
U test voltage measured as a percentage of U
Smin
U minimum supply voltage
Smin
Figure 6 — Supply voltage profile for the reset test
4.6.2.3 Requirement
The functional status shall be minimum class C as defined in ISO 16750-1.
4.6.3 Starting profile
4.6.3.1 Purpose
This test verifies the behaviour of a DUT during and after cranking.
4.6.3.2 Test method
Apply the starting profile 10 times, as specified in Figure 7 and Table 3 or Table 4, simultaneously to all
relevant inputs (connections) of the DUT. A break of 1 s to 2 s between the starting cycles is recommended.
One or more profiles as described in Tables 3 and 4 shall be chosen in accordance with the application.
8 © ISO 2012 – All rights reserved

Key
t time
U test voltage
t falling slope
f
t rising slope
r
t , t , t duration parameters (in accordance with Table 3 and Table 4)
6 7 8
U supply voltage for generator not in operation (see ISO 16750-1)
B
U supply voltage
S
...