Why should a fuse be added to the neutral line in the control cabinet Does a fuse be needed for 24V

The neutral line in the control cabinet is generally not allowed to add a fuse, and the live wire must add a fuse. If both fire and zero are fused, then in the event of a short circuit, in case the neutral fuse is broken, but the fuse of the live wire is not disconnected. At this time, the electrician or operator will think that the control loop is out of power, but in fact, the control loop is still powered.

This can lead to a risk of electric shock.

If you want to realize that both the live wire and the neutral line are disconnected when the short circuit is shorted, then you can use the double pole micro-disconnection, and when the double pole micro-disconnection is disconnected, the live wire and the neutral line will be disconnected.

The 24VDC power module generally does not need a home fuse, because the general power module itself has overload and short circuit protection. However, specific to each circuit of 24V electricity, a fuse should be added, which is to prevent the failure of one circuit and affect other circuits.

The "neutral line in the control cabinet" you said may be the internal contactor, relay control line directly using the phase line to the neutral line 220V as the power supply (now generally use 380 220 control transformer isolation), if so, it is necessary to add a fuse, when the circuit is short-circuited, the fuse on the live wire and the neutral line can play a protective role (of course, if a direct short circuit to the ground occurs, the fuse of the neutral line will not be fused);

The 24V power supply, whether it is a rectified DC power supply or an AC power supply through the control transformer, must have a fuse in order to protect the equipment and lines of the upper level.

Switches and fuses are not allowed to be installed on the neutral line (i.e., neutral wire, zero trunk line) of the three-phase four-wire system neutral grounding power supply line, otherwise when the switch is pulled or the fuse is blown out, it is equivalent to the neutral line being broken, so that dangerous voltages may appear on the neutral line and threaten the electrical equipment and personal safety. For the zero branch line, that is, the zero line of the single-phase line supplied to the residential, office building, shop, warehouse, etc., since it only plays a working role here, it is advisable to install a switch and a fuse on the phase line and the neutral line at the same time. Here's why:

1) Compared with installing a fuse only on the phase line, it can increase the chance of the fuse blowing, which is conducive to short-circuit protection.

2) If only the switch and fuse are installed on the phase line, when the phase wire and the neutral line are connected to each other incorrectly (which is easy to occur when overhauling the line), the phase wire will be in an unprotected state. When a ground fault occurs on this phase wire, the fuse on the neutral line will not be blown (because the short-circuit current does not pass through the fuse), nor will the transformer total fuse be blown (because the fuse capacity is large), and the phase wire will always be in a ground fault state, which poses a threat to the system.

However, there is also a problem with the installation of fuses on both the phase line and the neutral line: when the line is short-circuited or overloaded, it is possible to blow the fuse on the neutral line first, and then the electrical equipment stops working, but the equipment is still energized, if you think that the equipment is out of power and go to overhaul, an electric shock accident may occur.

In order to be able to cut off the phase wire and the neutral wire at the same time, it is advisable to use a bipolar knife switch (with a fuse inside), or a knife switch with two fuses to avoid the danger of only cutting off the neutral line and not cutting off the phase wire.

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Problem description: Thank you! Analysis:

The fuse in the circuit can automatically blow when the current is too high. Ensure the safety of your home circuits. Some people think that since it is safe to install a fuse, wouldn't it be safer to install a fuse on both the live and neutral lines?

Not really. We know that, in general, there is no voltage from the neutral line to the ground, and the person standing on the ground touches the neutral line, and no current passes through the human body, so it does not endanger the safety of the person. The live wire has a voltage of 220 volts to the ground, and if you stand on the ground and touch the live wire, there will be an electric current passing through the human body and causing an electric shock accident.

If only the fuse is installed on the live wire (as shown in Figure 5 4), then when the fuse is blown, the lamp port, switch and connecting wire are detached from the live wire and only connected to the neutral wire. They have no voltage to ground, making them safe when accessing circuits.

If a fuse is installed on both the live and neutral wires, there is a possibility that the fuse on the neutral line will blow while the fuse on the live wire will be intact (as shown in Figure 5 5). At this time, although the circuit is automatically cut off, it will not cause accidents such as disasters, but the lamp port, switch and connecting wire are still connected to the live wire, and they still have a voltage of 220 volts to the ground. In this case, if you think that the power supply has been cut off and carelessly, touching it is most likely to cause an electric shock accident.

It is better and safer to have a fuse only on the live wire than on both the live and neutral wires. From this, we can think that the power switch must be installed in the live wire.

However, in places with ** and fire hazards, in order to reduce the hazards of short circuit and overload, a fuse can also be installed on the neutral line. In addition, some of the distribution boxes in the home are also equipped with fuses on both the live wire and the neutral line to avoid the danger caused by the mistake of the live wire and change when the residents modify the line by themselves. Therefore, when you have to touch the circuit, you must first try it with a voltage detector to determine which one is the live wire.

Summary. Hello, I am happy to serve you and give you the following answers: No, the hot fuse must be connected to the ** and neutral wire, otherwise a short circuit will occur, causing the circuit to burn out.

Workaround:1Check whether the thermal fuse is connected to the ** and neutral wires, if not, then connect the ** and neutral wires; 2.

Check whether the hot fuse is in good contact, and if it is bad, replace it with a new one; 3.Check whether the thermal fuse is overloaded, and if it is overloaded, replace the thermal fuse with a larger capacity; 4.Check whether the circuit has a short circuit, if there is, then check the circuit and rule out the short circuit; 5.

Check the circuit for leakage, and if so, check the circuit to rule out leakage. Personal tips: When installing the thermal fuse, be sure to check whether the thermal fuse is connected to the ** and neutral wire, and make sure that the contact is good to avoid short circuits and burn out the circuit.

Is it okay for the thermal fuse to only connect to the neutral line?

Hello, I am happy to serve you and give you the following answers: No, the hot fuse must be connected to the ** and neutral wire, otherwise a short circuit will occur, causing the circuit to burn out. Workaround:

1.Check whether the thermal fuse is connected to the ** and neutral wires, if not, then connect the ** and neutral wires; 2.Check whether the hot fuse is in good contact, and if it is bad, replace it with a new one; 3.

Check whether the thermal fuse is overloaded, and if it is overloaded, replace the thermal fuse with a larger capacity; 4.Check whether the circuit has a short circuit, if there is, then check the circuit and rule out the short circuit; 5.Check the circuit for leakage, and if so, check the circuit to rule out leakage.

Personal tips: When installing the thermal fuse, be sure to check whether the thermal fuse is connected to the ** and neutral wire, and make sure that the contact is good to avoid short circuits and burn out the circuit.

Excuse me, but please go into more detail?

Hello, I am happy to serve you and give you the following answers: No, the hot fuse must be connected to the ** and neutral wire, otherwise a short circuit will occur, causing the circuit to burn out. Workaround:

1.Check whether the thermal fuse is connected to the ** and neutral wires, if not, then connect the ** and neutral wires; 2.Check whether the hot fuse is in good contact, and if it is bad, replace it with a new one; 3.

Check whether the thermal fuse is overloaded, and if it is overloaded, replace the thermal fuse with a larger capacity; 4.Check whether the circuit has a short circuit, if there is, then check the circuit and rule out the short circuit; 5.Check the circuit for leakage, and if so, check the circuit to rule out leakage.

Personal tips: When installing the thermal fuse, be sure to check whether the thermal fuse is connected to the ** and neutral wire, and make sure that the contact is good to avoid short circuits and burn out the circuit.

Hello, happy to answer your questions! You can follow the steps to operate: the fuse is also commonly known as the fuse, it is an important protective element in the induction cooker, if the induction cooker finds a serious short circuit, the first to burn is the fuse, which cuts off the power supply to avoid damage to other components.

So how to detect the quality of a fuse? There are two commonly used methods: the first method is to observe whether the fuse is burned or burnt and blackened, and sometimes you can smell a burnt smell with your nose, which means that the fuse has been damaged.

The second method is to measure with the resistance level of the multimeter, adjust the multimeter function knob to the ohm level of 200 ohms, and then put the red and black pen of the multimeter on both ends of the fuse, if the measured resistance value is close to 0, it means that the fuse is normal. If the measurement is infinity, it can be judged that the fuse is damaged. Replacing the fuse with a new one can solve the problem, but before replacing the fuse, it is necessary to ensure that the other original components of the circuit remain normal, otherwise the new fuse will still burn out, which needs to be specially reminded.

Three-phase four-wire system.

In the circuit, because there is no guarantee that the load of each phase is exactly the same, the zero line is not allowed to break. That is, it is forbidden to connect the fuse on the zero line of the three-phase four-wire circuit.

In the home circuit is single-phase electricity.

There is no load imbalance problem. However, it is usually said that the fuse is only connected to the live wire, because if the fuse is also connected to the neutral line, once the zero line fuse is blown and the live wire fuse is not broken, there is still a 220V voltage on the electrical appliance, which may cause danger.

If the zero line is broken, it will only be charged when the electrical appliance is well insulated to the ground, otherwise the fuse on the live wire will also blow. Since it is insulated to the ground, as long as you don't touch it, there will be no danger, and the switch must be disconnected when overhauling the circuit.

In addition, due to the fault caused by leakage, the current on the live wire will be greater than the voltage on the neutral line, so the live wire fuse will blow first; Due to the failure caused by overload, the zero live wire is safe as long as one is broken.

Why are there two fuses in the home circuit.

There are two main reasons:

The first is to prevent users from reversing the zero live wire when modifying the circuit, causing potential safety hazards.

The second is that the "zero line is not electrified" is not absolute, the zero line is actually grounded at the transformer in the community, if the transformer is not well grounded, there will be voltage on the zero line, and once the zero line grounding is disconnected, the voltage on the first land of the zero line will also be close to 220V, at this time the fuse on the zero line can play a protective role.

The power supply and distribution line in daily life is composed of a "power live wire--- switch or fuse--- load --- power neutral line (earth)". Because the neutral line is grounded, people standing on the ground or non-insulating objects on the ground are connected with the earth, and the potential of people is the same as the neutral line, and there will be no voltage and current when people contact the neutral line, so it is safe. If a person touches the live wire, it constitutes a "power live wire--- switch or fuse--- load (person) - power neutral line (earth)" circuit, and the person will be electrocuted!

If the switch and fuse are installed in the live wire, when the switch or fuse is disconnected, the live wire is disconnected, and there is no power at the load end, but it is still connected to the neutral line (earth), and it is safe for people to come into contact. If the switch and fuse are installed on the neutral line, the circuit is still connected to the live wire after the neutral line is disconnected, and there is an electric shock, and people are at risk of electric shock.

Hello: Affirmatively:No, you cannotTarget.

If] is installed on the neutral line, and the switch or fuse is [The power supply cannot be disconnected】 …existsMajor hidden dangers!