Today, people use electric current to power a wide variety of devices. Depending on the power that the device requires, the voltage can be quite high. To protect expensive and powerful equipment, high-voltage fuses of 10 kV are installed.
General description of devices
It is worth saying that high-voltage fuses start at 1 kV. They protect equipment from defects such as short circuit currents and inadmissible overload currents.
These devices have several basic technical parameters, according to which they are chosen. Among them, the rated voltage, the rated continuous current and the dependence of the melting time on the magnitude of the current stand out. There is another parameter that is often referred to as breaking capacity. However, to characterize it, a characteristic such as rated cut-off power is used. High-voltage fuses of 10 kV, like any others, contain a fuse that is included in the protected circuit in a sequential manner.
Current limiting fuse
Those devices that are able to drastically reduce the current strength in the circuit if a short circuit occurs are called current-limiting. While too high a current begins to flow through this fuse-link, which occurs only during a short circuit, or a long overload occurs with an increased current, it begins to melt. First, it goes into a liquid, and then into a gaseous state. At the time of smelting of this metal insert, an arc will form at the high-voltage fuse of 10 kV, however, as in any other similar device.
The duration of burning of this arc, as well as the time required to extinguish it inside the fuse, will depend on the design of the device itself, as well as on the type of fuse. Only after the arc is completely extinguished does the chain break completely.
Burning time
The burnout time of this fuse-link in 10 kV high-voltage fuses is a very important indicator. This parameter depends on how much current will flow through the fuse. Most often, the obtained value is called either a protective or a temporary characteristic of the fuse insert. From this value, you can determine how long it will take the device to disconnect the circuit at the selected current value. Using special calculations, it will also be possible to find out the parameters for the selective operation of fuses and the relay protection of an electrical installation.
It is important to know that the current that can melt the fusible element also depends on the design of the device, on the physical data of the element itself, for example, on the material, shape, length, cross section. Many do not know, but in this case, the ambient temperature will also make a significant contribution. It is worth adding that a 10,000-volt high-voltage fuse can be operated long enough if either its rated or lower electric current passes through its fusible element. During the conductive electric current of the operating value, the insert will also heat up, but at the same time it does not lose its shape and structure at all.
Rated current and fuse features
It is worth mentioning that the device has a rated current of the fuse element, and there is a rated current of the fuse itself. In the first case, we mean the value of the current at which it does not melt the insert. In the second case, the currents that the current-carrying part of the device can withstand are meant. These values are most often indicated on the parts themselves, that is, on live parts, as well as on contact frequent inserts.
There are several key indicators that a high-voltage fuse must meet. This includes stability, reliability and selectivity. If everything is clear with the first two requirements, then by selectivity we mean that the fusible element must operate under rated load for a long period of time, it should not turn off the devices during short-term overload, which often occurs when the equipment is turned on, for example. There must be a reliable disconnection of the circuit during severe overload and the case of the fuse itself must not be destroyed. In addition, wherever a short circuit current arises, the device should only disconnect the part for which it is responsible. Usually in such cases, the device that is closest to the place of emergency overload should be the first to trip.
Limit and maximum breaking currents
High-voltage equipment has fusible inserts that will burn out at the moment when their temperature limit is reached. Most often, such protective devices are called borderline. Naturally, if the boundary current is close in value to the nominal or a little more than it, then in this case the fusible element is able to work normally at its performance.
There is another important parameter, which is called the limit breaking current. In this case, we are talking about the maximum current value that the selected fusible element can turn off.
It is important to know that this value must be either equal to or slightly larger in value than the maximum possible short circuit current in the protected circuit. If the fuse is chosen incorrectly for this parameter, then the duration of the arc can be too long, which will lead to the destruction of the cartridge of the device itself, and not just the fusible element.
PC devices
Most often, 10 kV FCT high-voltage fuses are used in indoor switchgears designed for the same voltage. For the same purposes, you can also use PC devices. For example, the PC series are fuses that belong to current-limiting devices.
The marking of these devices is disclosed as follows. The PC series means that it is a type of fuse with fine-grained quartz filler. The letter "T" indicates that the device is designed to protect power transformers. It turns out that the high-voltage fuses PKT are fine-grained quartz fillers designed to protect the power transformer up to 10 kV.
Microwave fuses
A high - voltage fuse for a microwave is just as necessary as in any other network with expensive equipment. Microwave ovens are a rather complicated household device in their design. The metal construction of the fuse for this device is as follows: a metal thread in the role of a fusible insert located in a glass bulb, as well as special tips on the ends of the bulb to make it convenient to install a protective device. If the current value goes to the nominal value, then the metal thread begins to glow. The heating rate increases with the passage of current. When the temperature of the filament reaches a certain value, the thread breaks, which is why the entire device is de-energized.
Microwave Fuse Types
In the microwave oven there are as many as three different types of fuse - this is a network and two high-voltage fuses.
The high voltage fuse for the microwave oven serves as protection for an element such as a magnetron. This is a high voltage transformer that needs protection. The protective element itself is structurally located next to it, but at the same time, if you pay attention to the circuit, you can notice that it opens the circuit between the input and output of the high-voltage unit.
As for the second fuse of a similar type, it is available only for those microwave ovens that have an electronic control panel. Moreover, such a panel should be powered by a small transformer of low power. He will be engaged in converting the electric current of the home network into the voltage that is required for the panel to work.
Advantages of the PCT Series
There are several main advantages why the PCT series is popular. This may include, for example, the fact that the cartridge is made of high-quality and heat-resistant porcelain, which is additionally covered with waterproof glaze. It uses quartz sand, which is characterized by a high degree of purification. In addition, a special filling technique is used to achieve a very dense distribution of grains of sand. This is important since this factor provides a very effective arc extinction.
In the end, it is worth adding that under the dimensions of a high-voltage fuse of 10 kV, we mean the dimensions of its cartridge in length and diameter.