Why does the resistor heat up?Why do thermistors burn out?

Sweat... The definition of pure resistance is a resistance in which all electrical energy is converted into heat and not into other forms of energy. For example, electric stoves, electric lights, etc.

When the electrons in the conductor are in the electric field force.

When doing directional motion under the action, it will constantly collide with metal ions, and when it collides, a part of the kinetic energy will be transmitted to the ions, which will intensify the thermal motion of the ions and lead to heating.

Obviously, the higher the current and the greater the resistance, the more frequent and violent the collisions will be, and the more heat will be generated.

First of all, you should know why it feels hot, because of the high temperature, and what is the high temperature?Temperature is just the feeling of the human body, the faster the microscopic particles move, the hotter the person will feel after contactAdd the microscopic particles to stop moving, which is called absolute zero.

Modern physics believes that the atoms of a conductor or semiconductor, that is, the nucleus, are immobile, but they vibrate near their position, and the higher the temperature, the higher the momentum. In the circuit, the electric field accelerates the directional movement of the electrons, which will inevitably touch the atomic solid, and the momentum of the electron part will be transferred to the atomic solid, which will increase the vibration of the atomic solid. Eventually, the person will feel warm after contact.

The electric current converts electromagnetic energy into heat energy through resistance, heat energy is the energy of molecular movement, electromagnetic energy is the energy of electric field and magnetic field, the electric field makes the charge move to turn electromagnetic energy into charge kinetic energy, and the charge in the resistance is the electrons and atoms in the material that compose the resistance, and their motion naturally becomes the thermal energy of the resistance as a whole.

Learn mathematics, physics and chemistry well, and learn to dazzle the world.

Summary. There are generally several reasons why thermistors burn out:

The instantaneous current of the thermistor is too large and breaks down the resistance coil;

The insulation protection of the resistance wire of the thermistor wears out, resulting in a short circuit between the coils;

The line voltage is unstable and fluctuates greatly, and the instantaneous voltage exceeds the guarantee index of the thermistor.

Hello, I have seen your question and am sorting out the answer, please wait for a while There are generally several reasons why the thermistor burns out: The instantaneous current of the thermistor is too large, breaking down the resistance coil;The insulation protection of the resistance wire of the thermistor wears out, resulting in a short circuit between the coils;The line voltage is unstable and fluctuates greatly, and the instantaneous voltage exceeds the guarantee index of the thermistor.

Circuit components also heat up during normal operation, especially in the event of a malfunction.

In particular, the working current of the high-power triode is very hot, and it is often equipped with a heat sink.

In addition to the resistance value of the wires, the circuit board will heat up due to the power carrying capacity of the components themselves. When the power carrying capacity is small, the components will heat up, and the heat will be conducted to the circuit board.

The design of the high-current lines on the circuit board is not reasonable. For example, the total cross-sectional area of copper foil is less than 3 ampere amperes per square millimeter. The heat dissipation conditions and environment of the circuit board are not good.

For example, if it is too close to some heat-generating or heatsink-dissipating devices, there is no necessary ventilation duct or the circuit board is completely sealed, so it cannot dissipate heat, and the heat will slowly accumulate and cause the circuit board to heat up. The total power margin of the board is on the small side. In particular, the power consumption margin of the circuit board carrying the power function should be about double.

If necessary, you can also add a cooling fan.

Thermal resistanceThe relationship with resistance: the resistance value is constant, the voltage changes, the current changes, and the power of the shed also changes at any time. The resistance used in real life is generally a constant value, and some automatic adjustments are also fixed values, that is to say, the resistance must be This is the premise, and voltage fluctuations lead to current fluctuations and finally affect power.

Generally speaking, the purpose of resistors is nothing more than to limit current, divide voltage, or generate heat. But RTD.

The use of the use is different. It is a component that is specially used to measure temperature in industrial production.

The resistance of such a resistor is approximately linear in relation to the temperature it feels. For example, there is a RTD model called PT100 at 1 degree Celsius.

At 100 ohms, the resistance rises by about 1 ohm for every 1 degree increase in temperature, and at 100 degrees, the resistance is in ohms.

Compose. A two-terminal electronic component made of resistive material and a hood that has a certain structure and can play a role in restricting the passage of current in a circuit.

If the resistance value cannot be changed, it is called a fixed resistor.

Those with variable resistance are called potentiometers.

or a variable resistor. The ideal resistor is linear, i.e., the instantaneous current through the resistor is proportional to the applied instantaneous voltage. Some special resistors, such as thermistors, varistors, and sensitive components, have a non-linear relationship between voltage and current.

The above content reference: Encyclopedia - Resistors.

Not necessarily, the resistor itself consumes energy, and if the current flowing through the resistor is too large, it will generate heat.

At this time, you should check whether the current is normal, if not, it means that there is a short circuit in the circuit, and it should be eliminated as soon as possible. If the resistor is broken, it will not heat up.

The standard specifies the permissible ambient temperature range for resistors, such as -55 +100 or -55 +125 °C for general carbon film resistors and -55 +125 and -55 +250°C for wirewound resistors. When working, its temperature does not exceed this range, that is, it is allowed. Usually, as long as it does not exceed the rated power, there is no problem.

The power in the circuit is hot, not because of itself. Nor is it damaged. And Wang Lao is the current flowing through the resistance exceeds the rated value. Indicates that there is a short circuit in the adjacent circuit. or the original is damaged.

The problem of severe resistance hot is very common, and the harm it brings is not to be underestimated, so it is necessary to solve the problem of hot resistance. In order to solve the problem of hot resistors, the following reasons should be considered in the car, including circuit overload, the material and quality of the resistor itself, and the use of the car.

First of all, circuit overload is one of the common causes of hot resistors. When the load on the circuit is too high, the resistor will heat up due to long operation. The solution to this problem is generally to reduce the load by increasing the number of resistors or reducing the circuit voltage.

Secondly, the material and quality of the resistor itself are also an important reason for the resistance to be hot. When a resistor is of poor quality or fails, it causes the resistor to get hot easily when in use. At this time, it is necessary to replace some resistors, which have always been highly efficient, difficult to age and have strong puncture force, so they are less likely to get hot.

Finally, usage is also one of the factors that cause the resistor to get hot. If the resistor is used incorrectly or too frequently, it will lead to damage and hot phenomenon of the resistor. Therefore, when using resistors, it is necessary to choose a resistor that meets the equipment standards, and at the same time use it correctly according to the resistor's instruction manual, and try to avoid overuse.

In short, the solution to the problem of severe resistance burning is to find the root cause of the problem and solve it at the source. In the face of this situation, we can start from the above aspects, investigate the causes one by one, and take effective measures to solve the problem of hot resistance. <>

When the current and time are constant, the greater the resistance, the more heat is generated, i.e., q=i 2rt; When the voltage and time are constant, the greater the resistance, the less heat is generated, i.e., q=(U2R)t. In the case of the same current, the greater the resistance of the resistor, the higher the voltage that needs to be applied to both ends of the resistor.

The series connection of resistors has the following characteristics: (refers to R1 and R2 in series, the more strings, the greater the total resistance).

Current: i=i1=i2 (the current is equal everywhere in the series circuit).

Voltage: u=u1+u2 (the total voltage in a series circuit is equal to the sum of the voltages of each part of the circuit).

Resistance: r=r1+r2 (the total resistance in the series circuit is equal to the sum of the series resistance); If n equivalent resistors (r) are connected in series, then there is r total = nr.

Note: The total resistance is greater than any one of the sub-resistors, and the reason is that the resistance series is equivalent to increasing the length of the conductor; Practical significance: Replace large resistors with multiple small resistors in series.

Voltage divider: u1 u2=r1 r2 (the greater the resistance value, the more voltage will be divided, and vice versa, the less voltage will be divided).

Proportional relationship: In a series circuit, the work done by the current on each part of the circuit (electrical appliance), the heat generated, and the power of the work done are proportional to its resistance, w1 w2=q1 q2=p1 p2=r1 r2, u1 u2=r1 r2.