Research and Treatment of Wire Joint Thermal Failure

In the wiring, the connection of wires is an important obligation. Inevitably there are a large number of wire connectors in the wire. Wire joints can only find results through manual inspections and introspection, which is a weak link. Whether the operation of the line is safe or not depends to a large extent on the quality of the wire connection point. The wire connection point is the site where the fault rate is higher, and the contact point will cause heat to damage the insulation and equipment, and it will cause fire accidents.

1. Wire connector fever phenomenon and its harm

(1) Ordinary performance first is that there is odor around the wire joints, which can be smelled. This is due to the fact that the wire joints produce heat to make the outsourcing insulation odor;

(2) Smoke, redness at wire joints, blackening of outer insulation, fire, and even broken wires.

(3) The heat generated by the wire connector will not only constitute a large amount of power loss, but will also seriously affect the normal obligations of the electrical equipment, as well as fire and electric shock accidents.

Analysis of causes of wire connector heating

1 poor installation quality

The connecting wires are not constructed according to the rules, the joints are not firmly connected, and they are prone to loose; the conductive and switch, the electrical appliances are connected by the column, the terminals are not provided with washers, the nuts are not tightened, and the contact resistance is also increased; copper wire Aluminum wires are not connected according to the rules, and the contact resistance is relatively large, which constitutes a hidden danger.

Loose joints

Some joints are of good quality when installed, but due to thermal expansion and contraction, they may be temporarily shaken and the joints may loosen.

3. Oxidation at the junction

In a humid and corrosive gas environment, an oxide layer is easily formed on the conductor. The oxide has poor wire function and temporary operation may cause fever.

Several commonly used ways to check the junction heat.

1. The method of smelling

Using a nostril to check whether the wire fittings have a burnt smell is the most complicated method.

2 candle test

Tie the candle to the contact point of the insulating rod end. If it melts slowly, the temperature is about 55°C. If it melts quickly, the temperature should be above 70°C. If it is melted quickly and fumes, the temperature should be above 200°C.

3. Observation method

1 If the insulation tapes of the wire connectors are yellowed or blackened, the connector temperature must be above 70°C.

(2) See contact method on rainy day: see contact point monotonously on rainy day, the temperature is above 50°C; if raindrops vaporize and vaporize immediately, the temperature is above 100°C;

3 snow snow melting method: look at the contact on the melting snow, the temperature is about 0 °C or more; such as the contact monotonous, the temperature is about 50 °C above.

4 Observe the hot air flow method: When the temperature difference between the heating element and the air reaches about 20°C, you can see the huge airflow;

Thermometer

Infrared thermometer is an advanced instrument that is easy to use and has good contact detection

Temperature measurement stickers

Temperature measurement stickers have a common color temperature display, reflective display and temperature record function. They are self-contained with pressure sensitive adhesive. They are used in the connecting area of ​​busbars of substations, and they can also be connected to the connection points of busbars and device connection terminals and the switches of partitions. The contacts can also be attached to the shells of electrical equipment such as transformers, capacitors, and motors to monitor the temperature at the bus junctions and the electrical equipment enclosure. Once the temperature at the temperature monitoring site reaches or exceeds the rated temperature of the temperature measuring patch, the color temperature measuring patch will immediately change color.