Is an overload a short circuit? What is the difference between an overload and a short circuit?

Overload and short circuit are not the same thing;

The so-called overload means that the actual load current is greater than the rated current of the line or equipment. Overload can cause excessive temperature of lines and equipment, accelerated aging of insulation, and shortened service life. If it is overloaded for a long time, it will cause damage to the equipment and even lead to major accidents such as disasters and accidents.

The so-called low voltage or too low voltage means that the line voltage is lower than the rated voltage of the equipment. The long-term low-voltage operation of electrical equipment not only increases the power loss of the power supply line, the lighting is dim or cannot be ignited, the output and efficiency of the motor are reduced or cannot be started, and it will also cause overcurrent and cause the motor to overheat or even burn.

A short circuit is a state in which the wires leading from a power source to an electrical device (also known as a load) are directly connected to each other without passing through the load (or the load is zero), also known as a short circuit state. The hazard of short circuit is: the short circuit current generated by the short circuit far exceeds the allowable current limit of the wire and equipment, resulting in overheating or burning of electrical equipment, and even leading to disasters.

Overload. Is it just a short circuit?

1.Overload. --Overload means "overloaded" and "too high", for example, our household appliances are generally 220V alternating current.

The voltage suddenly rises to 380V, which burns out the washing machine motor that is running at home, which is called voltage "overload"; The original power of the audio amplifier was 35W, and later changed to 65W, and as a result, the two satellite boxes and the subwoofer were burned out, which is called current "overload".

2.Short circuit. --A phrase commonly used in electrical repairs, "short circuit".

It means that the breakdown of this component (e.g., capacitor) (i.e., the penetration of the positive and negative electrodes) causes a "short circuit" (i.e., the positive electrode passes through the baseplate); In other words, the positive current (or live wire) hits the iron (i.e., touches the iron shell) and causes a "short circuit".

What does short circuit, open circuit, leakage, and overload mean? Novice electricians, stop being stupid and can't tell the difference.

No. Overwhelmed is called overload; Positive and negative intersect, and no load is called a short circuit.

A short circuit is a circuit where two points are connected with only 0 resistance wires, and the voltage difference between the two points is 0

Overload is the overload operation of the circuit element exceeding its own rated power, and in the case of the motor, overload refers to the resistance torque of the load exceeding the output torque of the motor, which is manifested as an increase in current;

The main differences between short-circuit protection and overload protection are:One of the differences: Nakazakura overload current will flow through the load.

and short-circuit currents.

No load will flow.

The second difference: the overload current is generally the rated current of the load.

The short-circuit current can reach more than ten times to dozens of times of the negative ear load current.

The third difference: the thermal shock and electrodynamic impact of the overload current on the line and switching appliances are not very large, but the impact caused by the short-circuit current of the hidden peib is much greater. Therefore, the ability of switching appliances to withstand the impact of short-circuit current is called dynamic and thermal stability.

Self-locking circuit with overload protection.

Overload is the overload, exceeding the rated load of the equipment itself, the phenomenon is that the current is too large, the electrical equipment is heated, and the long-term overload of the line will reduce the insulation level of the line, and even burn the equipment or line;

It means that the current in the circuit exceeds the rated load, which will cause damage to the electrical components, and if a protective circuit breaker is installed, the circuit breaker will trip.

When the current flows through the wire, it heats up the wire and increases the temperature. In electrical wiring, the amount of current that is allowed to pass continuously without overheating the wire is called the safe ampacity. If the current flowing through the wire exceeds the safe current carrying capacity, it is called wire overload, that is, the wire is overloaded.

1. The reasons for the occurrence of barricades are different.

A short circuit is a low-resistance short circuit between conductive parts of different potentials, which is equivalent to a closed circuit when the power supply is not under load and the Sakura is directly connected by the wire.

Overload is because the equipment is operating under too much load, exceeding the rated load of the equipment itself.

2. The performance is different.

A short circuit is manifested in a circuit in which the current does not flow through the electrical appliance, but is directly connected to the positive and negative poles of the power supply.

Overload is manifested as excessive current, large heat generation of equipment and lines, abnormal noise of equipment, etc.

3. The consequences are different.

Short circuit: Since the resistance of the wire is very small, the current on the circuit will be very large when the power supply is shorted. Such a large current, the battery or other power sources cannot withstand it, which will cause damage to the power supply; What's more, because the current is too high, the temperature of the wire will rise, and in severe cases, it may cause a fire.

Long-term overload of equipment can reduce the level of line insulation and even burn the equipment or line ridge balance path.

1.The fault current of the short-circuit fault is larger, the setting current action value of the short-circuit protection is close to the larger point of the wire bearing, and the overload protection is located on the motor control loop, and the thermal relay is generally used, and the setting value is a multiple of the rated value of the motor.

2.Short-circuit protection refers to the protection made by the insulation of the circuit has been destroyed, and overload protection is the protection when the circuit insulation is intact and overcurrent occurs.

3.The overcurrent value of short-circuit protection is generally large, and the overcurrent value of overload protection is relatively small. In the low-voltage short-circuit protection, the circuit breaker is used for protection, because it can break the large current, and the overload protection is protected by a thermal overload relay + contactor, and the breaking current is small.

4.Short-circuit protection and overload protection are two different types of protection circuits, but both generally exceed the carrying capacity of the wire.

Extended Pre-Ascension Materials:

Short-circuit protection is the protection of short-circuit faults caused by the electrical short-circuit of conductors of unequal potential in the power supply system. The principle of selection is that when the line power supply is normal and the maximum load is included, even if the impact of the maximum starting current of the motor is included, the short-circuit protection action should be made. At the same time, when there is a minimum short circuit in the line, the short circuit protection should act reliably (the sensitivity coefficient is not less than.

Overload protection is an overload protection device installed to prevent the main power supply line from overheating and damage to the protector due to overload. Overload is a broad term that can refer to an excessive load on an electrical device or an object subjected to excessive force. The protection of these over-the-top behaviors is collectively referred to as overload protection.

In the communication power supply system, the function of automatically disconnecting the power supply of the power supply equipment due to excessive load is called overload protection.

A short circuit is a fire caused by the positive and negative poles touching the sedan ant somewhere and causing a fire when the line is hot or closed. An open circuit is when the line is cut and no current is passing through. Leakage is caused by the absence of a grounding wire in an electrical appliance. An overload is a safe range value exceeded.

The short-circuit current is hundreds or even thousands of times the rated current, and the overload current is several times the rated current.

The meaning of the two is the same, the short circuit is the positive and negative electrodes are connected, and the overload is the excessive use of electrical appliances.

A short circuit must be overloaded, and an overload is not necessarily a short circuit", this sentence can be understood!

When the positive and negative poles are connected during a short circuit, the result is that the current is too large and the appliance may be burned out.

Overload is when the circuit has too many electrical appliances that cause excessive current or excessive power consumption. This may cause voltage instability.

It's big, but not to the same extent.

The overload may only be a few times to several times the calibrated amount, while the overload may reach thousands of amperes.

Some air switches have two kinds of protection, overload delay protection, overload delay protection for a few seconds to tens of seconds, and if it is restored during the delay time, it will not be protected.

Short-circuit protection, if there is a short-circuit phenomenon, protect immediately.

In the power system BAI, short circuit and overload (overload) are two concepts that are absolutely different. Overload means that the negative DAO charge current only exceeds the fixed current.

Within 20% of the right, as long as the temperature rise does not continue to rise, the relay protection will only send out an electric bell warning sound to remind the personnel on duty to pay attention, and the trip protection will not be started, and the operation can continue. The short circuit is absolutely different, the short circuit current (for infinity) will generally be more than 5 times the rated current, which is not allowed in the power system, the relay protection will trip immediately, and send out a beep to remind the personnel on duty to pay attention.

A short circuit in a circuit can be seen as an extreme case of circuit overload.

In a circuit, usually the voltage is constant, then specialized.

Current (i) = voltage (u) Load resistance (r) means that when the load resistance (r) is too small (for example, there are too many electrical devices connected in parallel), resulting in excessive current (i) and exceeding the capacity of the power supply equipment, an overload will be formed; When the load resistance (R) tends to zero, the current tends to infinity instantaneously, that is, a short circuit is formed.

The short circuit is not directly connected to the circuit through the electrical appliances, the current of the circuit will be very large, and the electric energy is directly consumed in the internal circuit of the electrical wire and the inner part of the power supply, which seriously damages the wire and the power supply, and is the smallest in terms of the probability of occurrence, which is to be avoided as much as possible. In the case of a large multiple of the rated current, it is sometimes treated as a short circuit, and more than 6 times is considered a short circuit.

Overload is sometimes a normal phenomenon, especially for the motor is necessary, and it is considered overload. In case of overload, it is permissible to return to normal state as long as it does not exceed the specified temperature rise.

It is two completely different plagiarisms, and the short circuit is the live line interphase bai

Or the direct short circuit caused by insulation damage between the ground, which causes the line to be overcurrent, is very destructive and will lead to major accidents such as disasters.

Overload, on the other hand, is caused by the use of a large load that exceeds the design requirements, or the load is faulty, and the damage is much less than that of a short circuit. However, prolonged overload may cause a short circuit to occur. So avoid overload operation.

Refer to it.

Overload and short-circuit shutdown.

In order to protect the halogen lamp as soon as a high current is detected in the half-bridge circuit, the low-voltage lighting controller contains a protection circuit that prevents the oscillator from starting to oscillate for a period of time when excessive current is detected. In a conventional bipolar transistor-based natural system, a resistor that senses current charges capacitor C, keeping the transistor in the conductive state for a period of time proportional to the value of C.

When the transistor is on, the oscillator does not restart oscillation.

However, this mechanism is not reliable, for example, if it is dimmed with a halogen lamp, it often goes wrong. While it responds well to extreme short-circuit situations, it often doesn't respond correctly to overloads.

The shutdown circuit in the IR2161 monitors the load current on the CS pins to detect short circuits or overloads. In the event of a short circuit, the system must be shut down for several cycles of mains power to prevent it.

The MOSFET chip is damaged due to excessive temperature. In order to do this, the CS pin has an internal threshold voltage. If the voltage exceeds this level for more than 50ms, the system is shut down.

Inrush currents that occur when the system is turned on can cause false triggering, and using an external triac phase modulation circuit to adjust the brightness can also introduce transient currents that can cause false triggering. To prevent both of these false triggers, a delay of 50ms is essential.

Figure 3: Leading-edge dimmer in action.

It also has a lower threshold voltage, which has a much longer delay time before shutting down the system. This can be used to achieve overload protection, for example, when too many halogen lamps are connected to the output. If the output is short-circuited at the other end of the cable and the resistance of the cable is considerable, it will also react to prevent the current from being too high to trigger the short-circuit protection circuit.

The threshold voltage for overload shutdown is approximately 50% higher than the maximum load, and the delay is about seconds. This is achieved based on a current waveform whose envelope is sinusoidal and contains a high-frequency square wave component with a duty cycle of 50%.

Both shutdown modes are automatically reset, and after about seconds of shutting down the system, the oscillator begins to oscillate again. Therefore, after troubleshooting, the system can start working normally again, without having to cut off the grid voltage and then turn it on again. It also provides an overload indication for the end user:

If there are too many halogen lamps connected to the system, all halogen lamps will flash continuously.

A short circuit is a phenomenon in which the phase line or between the phase line and the neutral line is directly conducted, resulting in a sharp increase in the instantaneous high temperature and high heat current. Overload is when the load exceeds the rated value of the equipment. The short-circuit protection is realized by a fuse, which can be disconnected instantly, and the overload protection is realized by a thermal relay, which requires a certain amount of action time and is a cumulative process.

Short-circuit protection is when the circuit fails, such as not passing through the load, the resistance of the wire is almost negligible, so the instantaneous extremely large current provides a cut off the power supply, preventing equipment damage and causing accidents.

Overload protection means that when the total current caused by the load in the circuit that is in the starting state at the same time exceeds the rated current that the wire can bear, the power supply is cut off to prevent the wire from being damaged.

The so-called overload protection is also called overcurrent protection.

The so-called overcurrent, that is, the current flowing through the electrical equipment and lines, not only exceeds its rated current value, but also exceeds its allowable withstand time.

There are two kinds of overcurrent, such as the start-up of the squirrel cage motor, the starting current is much greater than the rated current, but it does not exceed the allowable time, so it is allowable overcurrent.

Overload protection is all about fault overcurrent. A short circuit is also an overload and is a serious overload phenomenon. It will cause great damage to electrical equipment and wiring, and even cause fire.

Overload protection generally uses an anti-time overcurrent protection device, that is, the larger the current flowing through the protection device, the shorter the time limit of action. Fuses also have certain anti-time characteristics. In addition, there are bimetal disc thermal relays, etc.

Short-circuit protection is generally instantaneous. There are electromagnetic, electronic and other forms.