What is the difference between a short circuit and an open circuit? Short circuit protector principle introduction

First, the difference in line performance when a short circuit and open circuit fault occurs

There are two reasons for the failure of the appliance to be powered. One is that the circuit is shorted and the other is the circuit is open. Before we can repair a faulty circuit, we must have an accurate diagnosis of the short circuit and the open circuit. To accurately determine the circuit fault, we must have an accurate understanding of short circuit and open circuit faults.

Both of these faults are characterized by the fact that the appliance is not energized as the first feature, and the specific performance is different.

Performance when a short circuit occurs : The short circuit of the circuit is caused by lightning strikes and excessive power load. When a short circuit occurs, a current interrupts the sound of the wire. A relatively short circuit can damage the power supply and cause a fire. Therefore, we must avoid this phenomenon in practical applications.

The performance when the open circuit occurs : the open circuit is caused by the disconnection of the wire in a certain part of the circuit or the failure of the electrical contact caused by the poor contact. The specific performance is that the appliance is not powered and cannot work normally.

When a break occurs, there is no strong performance like a short circuit. In practical applications, we can also observe the performance of the line when the electrical power is cut off to distinguish the circuit faults of open circuit and short circuit.

The difference between the measured value of the ammeter when the short circuit and open circuit fault occur

Short-circuit fault current measurement value: The short-circuit fault is caused by excessive current, so if we use the ammeter to measure the short-circuited line, it will show a large current. If the current is too large, it must be a short circuit fault.

Open circuit fault current measurement value: There is no current in the circuit breaker, so there is no reading when measuring the circuit breaker with current change. In practice, we can distinguish and diagnose based on the difference between the two ammeter measurements.

The difference between the measured value of the resistance meter when the short circuit and open circuit fault occur:

Short-circuit fault resistance measurement value: If we connect the resistance meter to the circuit and find that the resistance in the circuit is very small and close to zero, then the short-circuit phenomenon must occur.

Open circuit fault current measurement value: If we connect the resistance meter to the circuit and there is no reading, an open circuit fault occurs. After diagnosing the cause of the fault, if it is a short circuit, we must first disconnect the power supply and then perform maintenance. If it is a short circuit, we can use the ammeter to perform a segmentation test on the line, and detect the fault point of the open circuit and then perform maintenance.

(Insulation damage caused by short circuit)

Second, the principle of short circuit protector:

1. Short-circuit protector introduction : During the operation of the power system, our current will be abnormally contacted. For example, when the neutral line and the live line are in contact, or the leakage current, or the short-circuit current flowing through the electrode is the largest, a short circuit will occur. Phenomenon, in a large-capacity electrical system, the short-circuit current can reach tens of thousands of volts, which seriously affects people's normal life, and also has very significant consequences, so it is necessary to use short-circuit protection equipment, short-circuit protection equipment When the current overheats too much, the current is automatically cut off, so that the circuit system can be protected.

2, the working principle of short circuit protection : short circuit protection is to use the transistor in the current to sample the output current, according to the change state of the voltage before and after the short circuit to determine whether the circuit is short circuit, if the current is greater than the actual current seven, there are two reasons, the first The reason is that the electrical equipment is too large, and the second reason is the short circuit equipment in the circuit. We use a short-circuit protector to add an LED as an indicator. If a short-circuit occurs, the LED will automatically illuminate. After the continent is removed, the power circuit can be restarted to resume normal operation.

3, short circuit protector Note: When using short circuit protector equipment should pay attention to two aspects of the problem, the first problem is to avoid short circuit protection circuit shadow. When the system is started, it is necessary to choose to ensure that the short-circuit protection starts to move longer than the system startup time, so that it will not affect the system startup. Second, choose the appropriate resistor and LED, so that it will not affect the input and output. The circuit voltage can also protect the normal operation of the circuit.

Trading Club also offers you a variety of circuit breakers to choose from to protect your circuit.