Contents
In the process of using electrical appliances, they need to organize reliable protection. After all, often during their use, they are subjected to pulsed voltage surges, a sharp increase in current, short circuits and other dangers.
All this can not only disable expensive equipment, but also lead to more disastrous consequences – ignition and subsequent fire.
Electrical protection levels
Not surprisingly, today more and more devices connected to the electrical network are equipped with high-quality protection.
Basically, such protection of electrical appliances, which can consist of one or more levels, and from a technical point of view in different devices can be implemented in different ways, guarantees automatic disconnection from the power source in case of a short circuit, protecting subnetwork equipment from damage, and the electrical appliance from heating and ignition.
As the complexity of the protected device grows, so does the functionality of its protection mechanisms. For example, there are voltage stabilizers.
But such devices are quite an expensive luxury in our time, although if you think logically, then, for example, a plasma TV costs a lot more.
Simple and at the same time popular examples of them are fuses familiar to everyone, as well as current control relays less familiar to ordinary citizens.
See also:
Circuit breakers
The simplest means of protecting electrical appliances are fuses that protect equipment and wiring from sudden voltage drops.
Many people have already forgotten that there is such a way to protect electrical appliances, but in vain, because it works, although it is a little inconvenient.
They are installed in special cartridges, which can be located in a variety of places – switchboards, inside devices connected to the network, in network filters.
A typical fuse consists of a porcelain or glass body with metal contacts attached to it at both ends, connected by a thin wire.
Old models of fuses outwardly resemble the screw base of an incandescent lamp, while their modern counterparts have lost this similarity.
When the current flowing through the fuse exceeds the allowable value, it heats up and melts the wire, which bursts and breaks the circuit.
As a result, dangerous voltage does not have time to reach the equipment and damage it.
In fact, the fuses are disposable – after the wire breaks, they cannot be repaired and must be replaced. They can only be used in low-voltage networks with voltages up to 1000 volts.
See also:
Current control relay, device and principle of operation
More complex and more advanced devices for protecting electrical appliances from current that has gone beyond the rated values.
Their use is especially justified in conditions where power surges and short circuits occur frequently, and the operation of replaceable fuses is impractical, both in terms of cost and convenience.
See also:
For example, such relays are actively used in production. They consist of a specially shaped armature mounted on an axle, one end of which is provided with a spiral-shaped spring.
The design also includes an electrical steel core equipped with a magnetizing winding.
The controlled current, passing through the core, magnetizes it, due to which its poles attract the armature to themselves. He, in turn, tries to pull the axle behind him, in an attempt to turn it.
But the axis is firmly held by a spring that prevents its movement. As soon as the current exceeds the allowable rating, the strength of the electromagnet increases, as a result of which the armature overcomes the resistance of the spring, thereby turning the axis. As a result, the contact bridge installed on the insulating washer near the armature closes the fixed contact, and the circuit breaks.
Unlike disposable fuses, the current monitoring relay is considered a reusable protection device. As soon as the current level drops back to nominal values, the strength of the electromagnet drops, and the armature becomes weaker than the helical spring.
The axle returns to its normal position and chain integrity is restored. The relay continues to function normally, automatically connecting the protected devices to the power source.
See also:
Summing up
Both at home and at work, people periodically have to deal with the unstable behavior of the current in the electrical network.
Voltage fluctuations can ruin expensive equipment, as well as lead to much more serious consequences, such as a fire.
There can be many reasons for this – old wiring, electrician errors, and various external factors.
Therefore, in order to prevent the harmful effects of such drops, it is important to take care of appropriate protection in advance. Choosing the right protective device is the key to your safety.