Voltage dips in the network are a serious problem for many devices, because they can reduce the quality of the devices, as well as cause a malfunction in the devices connected to such a network. This phenomenon is much more common than a regular interrupt. Therefore, you should know what the dangerous voltage dips are, what are the reasons for their occurrence, how to protect yourself from this type of problem and how to deal with them. This is exactly what this article will be about.
Content:
- What is voltage dip
- Causes of failures
- Huge pressure
- Network origin
- Protection methods
What is voltage dip
According to European standards, a voltage dip is a sharp drop in effective voltage values to between 90 percent and 1 percent of the specified voltage. After that, there is a rapid rise or restoration of tension. Such dips are short-term, their duration is from half a period to one minute.
The normal operating state of the mains voltage should not fall below 90 percent. If there is a drop of only 1 percent of the set effective value, then this is an interrupt.
Accordingly, failure and interruption are not the same thing. The interruption appears only after the fuse has blown. Thus, a power outage in the power grid spreads in the form of a dip throughout the distribution network.
Causes of failures
Huge pressure
When connecting some consumers to the network, a large load is created. Such devices include, for example, powerful electric motors, which, when starting, use significantly higher currents than the rated ones. If the wires are designed only for the rated current, then the starting currents can seriously reduce the voltage in the network.
This phenomenon is directly related to the reserve of the power grid completely in accordance with the power, as well as with the resistance at the point of common connection, and in exact accordance with the resistance of the wire. Voltage dips caused by inrush currents have low voltage drop data, and at the same time are characterized by a sufficiently large duration in comparison with the gaps caused by faults in the distribution network, and can last from 1 to 10 seconds.
There are methods for eliminating problems with devices that have occurred due to the resistance of the wires. Devices with a large load can be connected to the network using common connection points or using a special secondary winding of the power transformer. However, if the problem is impedance at the common connection point, then more serious action must be taken to protect and correct the problem.
One of the options for solving this problem is to use a specialized converter frequency, with its help, a decrease in the magnitude of dips is achieved due to the distribution of additional load. Another additional solution to this problem can be the use of devices due to which the circuits are powered with less resistance. However, it should be noted that this solution is costly.
This problem poses a rather serious danger to electrical consumers and can lead to bad consequences, for example, a motor burnout in an electrical appliance. If the problem of failures could not be solved by the methods given above, then their effect on the devices can be eliminate with the help of stabilizers, electronic regulators, as well as dynamic reducing agents voltage. It is also important to remember that dips can be in any network, regardless of the voltage class.
Network origin
Power distribution is a complex process. From the network topology, the generator load at a specific point of the common connection, as well as the relative magnitude resistance depends on the level of impact of a certain damage in a certain area on other areas electrical network.
The duration of the failure that appears directly depends on how long it takes for the protective system to detect and, subsequently, eliminate it. This usually takes a couple of milliseconds. However, it should be remembered that there are damages that are accidental, for example, if a tree falls on overhead power lines. However, the speed of elimination depends on the nature of the fault and the parameters of the line and protections. If this is a line with an isolated neutral, then with a single-phase earth fault, the damage can be eliminated in up to two hours - for the time when the damage is found by personnel. The two-phase circuit, as a rule, is disconnected in a fraction of a second by the action of the protection against damage.
In the event of a complete shutdown of a certain area for a sufficiently long time with the help of automation, which serves as protection, all devices located on the site, must be completely de-energized until the problem is eliminated, and a check is carried out by specialists, and the power supply is restored to the damaged plot. An autorecloser can simplify this situation, and at the same time, it can contribute to the occurrence of more failures. Automatic reclosing restores the power supply after a time delay in the event of a protective automatics actuation. The time delay depends on the requirements for the power supply in the electrical network. For responsible consumers, the time delay is fractions of a second, for other categories of consumers, the time delay can be increased to several seconds.
In case of complete elimination of the damage, the equipment is restarted, and the power supply in the emergency section goes into a stable, normal state. However, if the damage was not eliminated during automatic reclosing, then the protective devices and with a minimum time delay de-energize the damaged area of the electrical networks. To prevent the development of an emergency, re-switching on the de-energized section is allowed only after the damage has been identified and eliminated.
However, if the damage was not corrected by means of a secondary activation, then it is necessary to re-enable the protective automatics. The repetition of this process will correspond to the number of times the user starts the automatic rotary switch program. It should be borne in mind that for each attempted secondary launch in all other sections there will be a second voltage dip, which means that other users will experience a whole series of failures.
Protection methods
So, you have learned what this phenomenon is, now let's talk about how protection against voltage dips in the network can be organized. If you need to protect a low-power load, it is enough to install an uninterruptible power supply (UPS). This solution can be applied even at industrial facilities for emergency shutdown of technological processes and safe storage of information.
If you need to protect a powerful load from voltage dips, in this case it is necessary to use specialized systems that carry out dynamic voltage recovery. Such systems are able to compensate for the missing part of the voltage, but this type of protection works for a short time. That is why they are not able to protect against prolonged voltage dips in the electrical network.
That's all that I wanted to tell you about what the voltage dips in the network are, what are the reasons for their occurrence and how you can protect the equipment from this phenomenon. It should be noted that computer equipment is most sensitive to failures. Therefore, if this phenomenon is observed in your network, be sure to protect the electronics with the above methods.
It will be helpful to read:
- What is the danger of a break in the neutral wire
- How to protect against overvoltage in the network
- How to choose a UPS
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