QC/T 1174-2022_English: PDF (QC/T1174-2022)
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High voltage fuse for electric vehicles
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QC/T 1174-2022
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| Standard ID | QC/T 1174-2022 (QC/T1174-2022) | | Description (Translated English) | High voltage fuse for electric vehicles | | Sector / Industry | Automobile & Vehicle Industry Standard (Recommended) | | Word Count Estimation | 28,281 | | Date of Issue | 2022-04-08 | | Date of Implementation | 2022-10-01 | | Summary | This standard specifies the technical requirements, test methods and inspection rules for high-voltage fuses for electric vehicles. This standard applies to high-voltage fuses for electric vehicles with a DC working voltage of 60 V to 1500 V. This standard does not apply to smart fuses and circuit breakers for electric vehicles. |
QC/T 1174-2022
QC
AUTOMOBILE INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 43.020
CCS T 09
High voltage fuse for electric vehicles
ISSUED ON: APRIL 08, 2022
IMPLEMENTED ON: OCTOBER 01, 2022
Issued by: Ministry of Industry and Information Technology of PRC
Table of Contents
Foreword ... 6
1 Scope ... 7
2 Normative references ... 7
3 Terms and definitions ... 7
4 Symbols and abbreviations ... 9
5 Requirements ... 10
6 Test methods ... 13
7 Inspection rules ... 25
Appendix A (Informative) Fuse installation method and installation torque ... 28
Appendix B (Informative) Structure of H-type and J-type fuses ... 29
Appendix C (Informative) Guidelines for application of fuse ... 31
References ... 36
High voltage fuse for electric vehicles
1 Scope
This document specifies the technical requirements, test methods and inspection rules
for high voltage fuse for electric vehicles.
This document applies to high voltage fuse (referred to as fuse) for electric vehicles
with a DC working voltage of 60 V to 1500 V.
This document does not apply to smart fuses and circuit breakers for electric vehicles.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this
document and are indispensable for its application. For dated references, only the
version corresponding to that date is applicable to this document; for undated references,
the latest version (including all amendments) is applicable to this document.
GB/T 2423.18-2012, Environmental testing - Part 2: Test methods - Test Kb: Salt
mist, cyclic (sodium chloride solution)
GB/T 2423.34-2012, Environmental testing - Part 2: Test methods - Test Z/AD:
Composite temperature/humidity cyclic test
GB/T 2423.56-2018, Environmental testing - Part 2: Test methods - Test Fh:
Vibration, broadband random and guidance
GB/T 13539.1-2015, Low-voltage fuses - Part 1: General requirements
GB/T 28046.3-2011, Road vehicles - Environmental conditions and testing for
electrical and electronic equipment - Part 3: Mechanical loads
GB/T 31465.1-2015, Road vehicles - Fuse-link - Part 1: Definitions and general test
requirements
3 Terms and definitions
Terms and definitions determined by GB/T 13539.1-2015 and GB/T 31465.1-2015, as
well as the following, are applicable to this document.
3.1 Fuse
Note 1: Pre-arcing I2t is the integral of I2t within the pre-arcing time of the fuse.
Note 2: Operating I2t is the integral of I2t within the operating time of the fuse.
3.10 Rated current
The current value that is used to identify a fuse, which is measured in accordance with
a prescribed method.
Note: The continuous working current of the fuse should be lower than the rated current,
and the use of derating can be in accordance with Appendix C.
3.11 Rated voltage
The maximum supply voltage applicable to the fuse.
3.12 Prospective current
The current that would flow in a circuit if the fuse is replaced by a conductor of
negligible impedance.
3.13 Operation mode
The operation mode is defined as follows:
a) operation mode 1: the fuse is not connected to the cable or copper bar;
b) operation mode 2: the fuse is connected to the cable or copper bar, but not
energized;
c) operation mode 3: the fuse is connected to the cable or copper bar and energized.
Note: The installation method of the fuse is in accordance with Figure A.1 in the
appendix; the installation torque is in accordance with Table A.1 in the appendix.
4 Symbols and abbreviations
In addition to the symbols mentioned in 3.9, the following symbols also apply to this
document:
I2t: joule integral;
IR: rated current;
RT: room temperature;
UR: rated voltage.
5 Requirements
5.1 Working environment
Unless otherwise specified, the fuse shall be able to work normally in the following
environmental conditions:
a) Temperature: -40 °C ~ 85 °C;
b) Relative humidity: 5% ~ 95%;
c) Atmospheric pressure: 61.6 kPa ~ 106.2 kPa.
5.2 Appearance
The appearance and identification of the fuse shall meet the following requirements:
a) The surface of the enclosure shall be uniform in color, smooth, flat and dry, and
shall be free from obvious scratches, burrs, rust, deformation, cracks and other
defects;
b) Product nameplates, plates, labels or indications shall be correct, complete, clear,
and reliably and permanently attached to the enclosure.
5.3 Dimensions and tolerances
The dimensions and tolerances of the fuse shall meet the requirements of the product
drawings.
5.4 Electrical performance
5.4.1 Requirements for internal resistance
Carry out the test according to 6.4.1, and the relative deviation between the measured
value and the internal resistance value declared by the manufacturer shall not exceed
±10%.
5.4.2 Requirements for temperature rise
Carry out the test according to 6.4.2. The temperature rise value of the fuse terminal
shall not exceed 50 K, and the temperature rise value at the center of the insulator can
be determined through negotiation between the supplier and the buyer. After the test,
the overall fuse shall not have obvious discoloration, the terminal, terminal plating and
label shall not be burnt and peeled off, and the fuse shall meet the requirements of 5.4.1.
5.4.3 Requirements for fusing
5.5 Requirements for environmental adaptability
5.5.1 Requirements for salt spray resistance
Carry out the test according to 6.5.1. After the test, there shall be no problems such as
peeling, chipping, blistering, peeling off of the coating or bare basic metal on the fuse
coating, and the fuse shall meet the requirements of 5.4.1 and 5.4.4.
5.5.2 High temperature requirements
Carry out the test according to 6.5.2. After the test, the fuse shall meet the requirements
of 5.4.1, 5.4.3 and 5.4.4.
5.5.3 Low temperature requirements
Carry out the test according to 6.5.3. After the test, the fuse shall meet the requirements
of 5.4.1, 5.4.3 and 5.4.4.
5.5.4 Constant damp and hot requirements
Carry out the test according to 6.5.4. After the test, the fuse shall meet the requirements
of 5.4.1, 5.4.3 and 5.4.4.
5.5.5 Requirements for combined temperature/humidity cycle
Carry out the test according to 6.5.5. After the test, the fuse shall meet the requirements
of 5.4.1, 5.4.3 and 5.4.4.
5.5.6 Requirements for cold and hot impact
Carry out the test according to 6.5.6. After the test, the fuse shall meet the requirements
of 5.4.1, 5.4.3 and 5.4.4.
5.6 Mechanical load
5.6.1 Mechanical vibration requirements
Carry out the test according to 6.6.1. After the test, the fuse shall not have problems
such as appearance change, loose screws, cracked and deformed insulators, and the fuse
shall meet the requirements of 5.4.1, 5.4.3 and 5.4.4.
5.6.2 Mechanical shock requirements
Carry out the test according to 6.6.2. After the test, the fuse shall not have problems
such as appearance change, loose screws, cracked and deformed insulators, and the fuse
shall meet the requirements of 5.4.1, 5.4.3 and 5.4.4.
6 Test methods
6.1 General conditions of test
6.1.1 Test standard atmospheric conditions
Unless otherwise specified, all tests shall be carried out under the following
environmental conditions:
a) Room temperature: 23 °C ± 5 °C;
b) Relative humidity: 5% ~ 95%;
c) Atmospheric pressure: 61.6 kPa ~ 106.2 kPa.
6.1.2 Test equipment
The instruments, equipment and loading conditions in the test shall meet the following
requirements:
a) The graduation value of the universal measuring tool for measuring the size shall
not be greater than 1 mm;
b) It shall have an appropriate range, where the graduation value shall not be greater
than 1 °C, and the calibration accuracy shall not be lower than 0.5 °C;
c) The accuracy of the instrument for measuring resistance shall not be lower than
grade 0.5;
d) The accuracy of the instrument for measuring current shall not be lower than grade
0.5;
e) The accuracy of the instrument for measuring voltage should not be lower than
grade 0.5, and the internal resistance shall not be less than 1 kΩ.
Note: Other equipment or instruments used can be determined through negotiation
between the supplier and the buyer.
6.2 Appearance
Samples shall be inspected by visual and tactile methods under sufficient natural or
fluorescent lighting conditions.
6.3 Dimensions and tolerances
General measuring tools shall be used to measure the dimensions and tolerances of
fuses.
Description of indexing numbers:
b – the time of each cycle.
Figure 3 – Overload impact
6.5 Environmental adaptability test
6.5.1 Salt spray resistance test
The salt spray resistance test process is as follows:
a) Fuses are tested under the conditions of operation mode 1;
b) Carry out in accordance with the provisions of the severity level (3) in GB/T
2423.18-2012;
c) A test cycle includes 4 spraying cycles, each 2 h; each spraying cycle is followed
by a 20 h ~ 22 h damp and hot storage cycle; after 4 cycles, carry out a storage
period of 3 days under the test standard atmospheric pressure and relative
humidity of 45% ~ 55%.
6.5.2 High temperature test
The high temperature test process is as follows:
a) Carry out the high temperature test according to Figure 4 and Table 5, wherein
Tmax is 85 °C;
b) The test current and the cross-sectional area of the test cable are selected according
to Table 2. If there is no corresponding current value in Table 2, it can be
determined through negotiation between the supplier and the buyer.;
c) If there is a problem of interruption during the test, the test can be continued from
the point of interruption. The test requires that the continuous test time shall not
be less than 96 h. If it is less than 96 h, the test needs to be repeated. The
interruption must be indicated in the report.
Appendix C
(Informative)
Guidelines for application of fuse
C.1 Introduction to fuse
C.1.1 Working principle of fuse
The working principle of fuse is that when the current exceeds the specified value for a
long enough time, it will fuse through one or several proportionately designed fuses,
thereby disconnecting the device connected to the circuit. A fuse contains all the parts
that make up a complete electrical appliance.
C.1.2 Fuse structure
The schematic diagram of the fuse structure is shown in Figure C.1.
The structural composition and main functions of the fuse:
-- Melt (fuse): Set the perception current, and use the thermal effect of the current to
melt or vaporize the conductor, and form a fracture after melting.
-- Narrow diameter of the fuse-element: The position on the fuse-element where the
cross section of the conductor is smaller is used to adjust the fusing speed.
-- Quartz sand: By absorbing the arc heat, reducing the arc temperature, wrapping
and absorbing the molten metal particles in the fracture, increase the arc voltage,
and extinguish the arc. It also isolates and buffers the mechanical impact and high
temperature impact on the enclosure.
-- Insulator (enclosure): heat-resistant insulation structure, resistant to arc
temperature and mechanical impact, keeping the overall integrity of the fuse.
-- Terminal: conductor connection, providing electrical connection and installation
mechanical force.
250 A, 300 A, 350 A, 400 A, 450 A, 500 A, 600 A, 630 A, 700 A, 800 A, 900 A,
1 000 A).
-- The rated current derating coefficient of the fuse is calculated as Formula (C.1):
Where:
In – continuous working current of the fuse;
IRMS – continuous working current of the fuse;
Ke – hot connection;
Kv – air cooling;
Kt – ambient temperature;
Kf – frequency;
Ka – altitude coefficient;
A2 – current periodic parameter;
A3 – load start-stop cycle.
-- The rated current derating coefficient of the fuse can be selected by referring to
the method in Appendix B.2.1 of ISO 8820-2:2005, and directly using the
multiple for the primary selection stage.
-- Determine the specification and model of the fuse, “simulate” or “test” the fusing
and protection parameters of the fuse specification, and submit it to the user for
evaluation or verification reference.
C.2.2.3 Check the model selection according to the vehicle type and working conditions.
C.3 Fuse failure modes
The common failure modes of fuses are as follows:
-- The rated voltage selection is too small, and the loop inductance is greater than
the standard test conditions: the circuit breaking voltage is higher than the rated
voltage of the fuse or the inductance is greater than the standard test conditions,
which may cause the fuse to exceed the conditions and cannot be reliably broken,
and it is prone to explosion and arc spray.
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