Electronics power harness for boat and Electrical appliances

Electronic power wiring harness (circuit group) is a cable assembly that provides connection services for load source components. For example, trunk lines, electronics, circuits, power supplies, switching devices, automotive control systems, etc. Custom wiring harnesses generally consist of wires, connectors, plugs, and terminals. The basic research content of traffic theory is to study the relationship between traffic volume, call loss and harness capacity. Therefore, wire harness is an important basic concept in traffic theory.

definition
The load source is the service equipment of the wiring harness, usually referring to different user equipment. Broadly speaking, the upper-level equipment is the load source of the lower-level equipment. In telephone communication, the load source is also called the voice source, and the number of service devices contained in the wire harness is called the wire harness capacity. Figure 1 is a schematic diagram of the wiring harness. The harness has a capacity V and it serves N load sources. Any one load source making a call may occupy an idle service device in the harness.

Composition of electronics and power wiring harness
1. In order to facilitate installation and maintenance, ensure that various electrical equipment can work under the worst conditions. The wiring harness integrates the wires of different specifications and colors used in the electrical equipment of the whole vehicle through reasonable arrangements. And use insulating material to bundle the wires, which is both complete and reliable.

2. Normal selection of wire cross-sectional area and color code
1) Correct selection of wire cross-sectional area
The electrical equipment on the car selects the cross-sectional area of the wires used according to the size of the load current. For electrical equipment that works for a long time, 60% of the actual current carrying capacity of the wire can be selected. Electrical equipment that works for a short time can use 60%-100% of the actual carrying capacity of the wire.
2) Selection of wire color code
The wires in the wiring harness are colored differently for easier identification and servicing.
For the convenience of labeling in the circuit diagram, the colors of the wires are represented by letters, and the colors they represent are noted in each circuit diagram.

Electronics power harness failure
Common faults in automotive circuits include: poor contact of connectors, short circuit between wires, open circuit, grounding, etc.
There are several reasons for this:
1) Natural damage
The use of the wire harness exceeds the service life, aging the wires, cracking the insulation layer, and significantly reducing the mechanical strength, causing short circuits, open circuits, grounding, etc. between the wires, causing the wire bundles to burn out.
2) Damage to the wiring harness due to failure of electrical equipment
When electrical equipment is overloaded, short-circuited, grounded, etc., it may cause damage to the wire harness.
3) Human failure
When assembling or overhauling auto parts, metal objects crush the wire harness, causing the insulation layer of the wire bundle to rupture; the positive and negative leads of the battery are reversed. When checking and repairing circuit faults, random connections, random cutting of wire harnesses, etc., can cause abnormal operation of electrical equipment.

Detection and judgment of electronic and power wiring harness
1) Detection and judgment of wire harness burnout fault
In the circuit of the power supply system, where there is a ground wire, the wire bundle will be burned, and the junction between the burned out part and the intact part can be considered as the wire ground at that place. If the wire harness is burned to the wiring part of an electrical equipment, it indicates that the electrical equipment is faulty.
2) Detection and judgment of short circuit, open circuit and poor contact between lines
– The wire bundle is subjected to external extrusion and impact, causing damage to the insulation layer of the wires in the wire bundle, resulting in a short circuit between the wires.
When judging, the wire harness connectors at both ends of the electrical equipment and the control switch can be disassembled, and the short circuit of the circuit can be detected with an ammeter or a test lamp.
– Conductor open circuit faults, except for obvious fractures, common faults mostly occur between the conductor and the conductor terminal. After some wires are disconnected, the outer insulation layer and the wire terminal are intact, but the inner core wire and the wire terminal have been disconnected. When judging, a tensile test can be performed on the conductive wire and the wire terminal suspected of being open. During the tensile test, if the insulating layer of the wire gradually becomes thinner, it can be confirmed that the wire has been broken.
– Poor contact of the line, most of the faults occur in the connector. When a fault occurs, it will cause the electrical equipment not to work normally. When judging, turn on the power of the electrical equipment, touch or pull the relevant connector of the electrical equipment. When touching a certain connector, the work of the electrical equipment is suddenly normal, and suddenly it is not normal, indicating that the connector is faulty.

Materials for electronics and power harnesses
The requirements for materials for automotive wiring harnesses are also very strict:
Including its electrical performance, material emission, temperature resistance, etc., are higher than the general wiring harness requirements. Especially when it comes to safety requirements are more stringent.
1. The ambient temperature around the engine is high, and there are many corrosive gases and liquids. Therefore, the wires of the engine wiring harness must use high temperature resistant, oil resistant, vibration resistant, and friction resistant wires.
2. The wires on the automatic transmission use wires that are resistant to hydraulic oil, high temperature, and have good temperature stability.
3. The wires of the wiring harness on the trunk lid should maintain their elasticity at low temperatures. Therefore, the cold elastic wire should be selected to ensure its normal operation.
4. Weak signal sensors should use shielded wires.
5. The ABS wire harness assembly uses stranded wires with a high temperature resistance of 150-200°C, a hard outer protective insulation layer, and wear resistance, but the wire core must be greater than 133.
6. Power wiring harness: such as starter and alternator output wires, and battery wires, the wires used are special wires that can withstand large currents, have good heat dissipation performance of the insulation layer, and have high voltage.