【Daily Question 20090327】Why do electrical installations often suffer from overheating problems?

Is no one going to participate? Let me start then. Common causes of overheating in electrical installations include prolonged operation under overload conditions, which is the main reason for overheating; other causes include poor contact at wire connections and equipment terminals, reduced pressure on the contacts of switching devices, and contact resistances that are not within acceptable limits. Also, check whether the equipment’s operating environment meets the requirements (whether ventilation and heat dissipation are adequate) and whether the equipment is securely fixed. Is there any vibration? Are the power supply parameters compatible with the device (such as voltage and frequency being within the specified ranges)? Is the device operating properly (for example, are there any mechanical wear on the moving parts, and is there a lack of oil)?

Overheating in electrical devices is generally caused by the following factors: first, the device operating under overload conditions. II. High external temperature; III. Failure of cooling equipment. Reasons such as failures in the cooling systems of the four large-scale equipment: handshake

All kinds of electrical equipment, whether stationary or rotating, must withstand a certain voltage once connected to the power system. As current flows through them, heat is generated and the temperature rises. Different electrical devices have different high-temperature overheating areas, due to their varying structures, working principles, and positions within the system. High-temperature overheating of electrical equipment is related to various factors, among which material properties, structural characteristics, insulation rating, and load level play a decisive role.

1. The contact areas of the contacts are subject to frequent operations, which can lead to a decrease in contact pressure, an increase in contact resistance, and higher losses. In addition, rust and oxide layers also contribute to an increase in contact resistance and rising temperatures. 2. Internal short circuits or partial discharges in the transformer. 3. Local overheating of the motor can be caused by overload or excessive voltage fluctuations, single-phase operation, winding short circuits, as well as poor ventilation and cooling systems and inadequate heat dissipation conditions. 4. Increased frictional loss leads to overheating. 5. The lead connections of the equipment may overheat during operation due to loose fixation or poor contact. 6. Insulators and insulating sleeves, due to the harsh conditions they are exposed to, tend to become dirty on their surfaces, which can lead to arcing and subsequent localized overheating.

Overheating is mainly caused by: 1. Electrical devices operating at full load or under overload. II. The external temperature is high; III. The cooling equipment is insufficient to meet the requirements, and the space is too small. IV. Poor contact at the lead connections of the equipment

0. The fundamental reason is that electrical devices are used to transmit and distribute electrical energy, and during this process, electrical energy is most likely to be converted into heat energy! I. Operating the equipment under overload by dragging it ； II. High external temperature ； III. Poor heat dissipation ； IV. Poor crimping at the connection points ； V. The circuit breaker size is too small, resulting in actual overload.

The main factors causing overheating in electrical devices include: 1. Unstable voltage, which is too high. 2. Excessive current. 3. After operating for a certain period of time, electrical devices experience an increase in temperature due to some of the electrical energy being converted into heat, which ultimately results in a decrease in their resistance and an increase in current. It creates a vicious cycle. 4. Excessive operating time, insufficient routine maintenance, and lack of timely repairs. 5. External factors: such as environmental temperature, ventilation facilities, the size of the space, and so on. This post was last edited by rongdragon on 2009-3-27 at 21:43.]

Overheating faults in electrical equipment can be divided into two categories: external heat faults and internal heat faults. First, external heat faults: These occur when exposed connections, due to poor crimping or other reasons, experience an increase in temperature under the influence of high currents, which in turn increases the contact resistance; this creates a vicious cycle that poses risks. Such failures account for over 90% of external thermal failures. By analyzing thousands of records of external thermal faults detected in recent years, it can be seen that thermal faults in clamps and circuit breaker contacts account for 77% of all such external thermal faults; their average temperature rise is around 30°C. The average temperature rise of other external connections ranges from 20–25°C. Based on the inspection experience from these past years, external faults can be classified into three categories according to their degree of temperature rise: mild, moderate, and severe. II. Internal thermal faults: The characteristic of internal thermal faults in high-voltage electrical equipment is that the fault site is enclosed within insulating materials or metal enclosures, such as cables. Such faults generally result in prolonged and steady heat generation; heat is transferred to the conductors or insulating materials surrounding the fault site, causing local temperature increases. Therefore, internal faults in high-voltage electrical equipment (such as cables) can be diagnosed by detecting the temperature rise of the materials surrounding them.

After operating for a certain period of time, electrical devices experience an increase in temperature as some of the electrical energy is converted into heat. This leads to oxidation of the contact surfaces, an increase in contact resistance, which in turn causes even higher temperatures, creating a vicious cycle.

Short circuit, overload, phase loss, vibration, looseness, roughness of contact surfaces, oxidation, insulation aging and damage, poor heat dissipation, overvoltage, ground fault

The last edit to this post was made by hao*shuai on 2009-7-31 at 20:28. Overheating faults can be of two types: The first type is as described by the friend above – it occurs due to poor contact, a small conductive area, or a sudden sharp increase in current, which leads to overheating of certain parts of the wiring or cables; this overheating can cause the conductors to melt, resulting in an open circuit. It can also damage the surrounding insulation and lead to a short circuit； The second is thermal breakdown: when a voltage is applied to a solid insulating medium but it does not reach the critical value, heat is generated due to losses, causing the temperature of the dielectric to rise. The resistance of dielectrics has a negative temperature coefficient; that is, as the temperature rises, the resistance decreases. This in turn causes the current to increase further, and heat generation also increases. Until a certain temperature is reached, the amount of heat generated is equal to the amount of heat dissipated, achieving thermal equilibrium. At this point, the temperature no longer rises, and the dielectric does not break down. However, when the voltage rises to a certain critical value (known as the critical thermal breakdown voltage), the heat generated is always greater than the heat dissipated; as a result, the temperature of the dielectric continues to rise, leading to local decomposition, melting, carbonization, etc. of the dielectric, which results in dielectric breakdown and thermal breakdown failures.

(1) First, check whether it is an over-negative symbol. (II) Whether the wire connections are loose. (III) Aging of internal components of the electrical appliance. (IV) Whether the wire is too thin. Additional note: Whether the equipment’s operating environment meets the requirements (proper ventilation and heat dissipation), and whether the equipment is securely fixed in place. Is there any vibration? Are the power supply parameters compatible with the device (such as voltage and frequency being within the specified ranges)? Is the device operating properly (for example, are there any mechanical wear on the moving parts, and is there a lack of oil)?

1. The voltage is too high. 2. Excessive current load and overload. 3. Poor electrical connection in the electrical apparatus. 4. Defects in the equipment. 5. High ambient temperature, poor ventilation, limited space, etc.