QC/T 707-2004Technical specifications for central electrical junction boxes of motor vehicles (English PDF)

3.1 Connecting plug

A conductive part of an electrical device on the center box used to electrically connect to an external circuit.

3.2 Connecting socket

A socket on the center box for connection to a relay plug or chip fuse with a certain clamping force.

3.3 Insertion force

The force required to insert the relay, fuse or standard insert into the center box.

3.4 Withdrawal force

The force required to withdraw the relay, fuse or standard insert from the center box.

3.5 Bridge blade

In the measurement of voltage drop, a kind of blade with different shapes used to connect the parts need energization and conduction after removing the relay or fuse.

4.1 General requirements

The center box shall comply with the specifications of this Standard and shall be manufactured according to the drawings and design documents approved by the prescribed procedures.

4.2 Temperature range

The center box is continuous rating. It shall be able to normally turn on and off within the temperature range of 40 °C ~ 70 °C (in the cab), -40 °C ~110 °C (under the engine hood), the storage temperature is -40 °C ~ 90 °C (in the cab), -40 °C ~ 130 °C (under the engine hood) respectively.

4.3 Shape and installation dimension

The shape and installation dimension of the center box shall comply with the specifications of the drawings of the product. Among them, the electrical connection of the external circuit is not allowed to use riveting and welding.

4.4 Appearance

The center box shall have no damage after being subjected to the resistance to disruptive voltage strength test with an actual sinusoidal voltage of 50 Hz, an effective value of 1000 V and a duration of 1 min.

4.10 No-load ventilation storage performance

The center box shall be subjected to a no-load ventilation storage test at 90 °C (in the cab) and 130 °C (under the engine hood) for 48 h. After the test, it shall be able to normally turn on and off, and shall comply with the specifications of 4.4 in this Standard.

4.11 Resistance to low temperature

The center box shall be able to normally turn on and off at -40 °C, and shall comply with the specifications of 4.4 in this Standard. The voltage drop allows an increase of 20 %.

4.12 Resistance to temperature alternation

The center box shall be subjected to a total of 4 cycles (6 h for one cycle) in the temperature range of -40 °C ~ 70 °C (in the cab) and -40 °C ~ 110 °C (under the engine hood). After the test, it shall be able to normally turn on and off, and shall comply with the specifications of 4.4 in this Standard. The voltage drop allows an increase of 20 %.

4.13 Resistance to temperature and humidity cycle

The center box shall be subjected to a total of 10 cycles (24 h for one cycle) of the temperature and humidity combined cycle test. After the test, it shall be able to normally turn on and off, and shall comply with the specifications of 4.4 in this Standard. The voltage drop allows an increase of 20 %.

4.14 Vibration resistance

The center box shall be subjected to the sweeping vibration test according to the specifications of Table 3 "Other parts" in QC/T 413-2002. After the test, it shall be able to normally turn on and off, and shall comply with the specifications of 4.4 and 4.7 in this Standard.

4.15 Durability (load ventilation storage)

The durability test of the center box shall be carried out by selecting the corresponding load procedure and test load from Figure A.1 of Annex A and Table B.1 of Annex B according to the product function and customer requirements, at the ambient temperature of 70 °C (in the cab) and 110 °C (under the engine hood) for 24 h. After the test, it shall be able to normally turn on and off, and shall comply with the specifications of 4.4 in this Standard. The voltage drop allows an increase of 20 %.

The overcurrent test of the center box shall be carried out on a dedicated test stand which can automatically display the values. During the test, according to different product features and customer requirements, select corresponding load procedure and test load from Figure A.1 and Table B.1, apply the current of 1.1 times the rated value of the fuse, for 1 h. After the test, it shall comply with the specifications of 4.8 in this Standard.

5.9 Resistance to disruptive voltage strength test

When having resistance to disruptive voltage strength test, firstly put the center box into the hot and humid chamber, to keep 24 h in a condition with the temperature of 18 °C ~ 28 °C and the relative humidity of 90 % to 98 %; remove and replace it at the normal environment for 1 h; apply 50 Hz 1000 V actual sine wave voltage between mutually insulated conductive parts and between the conductive parts and the enclosure. […]