Modern human life is unthinkable without electricity, which has greatly expanded the boundaries and possibilities of our existence. In order to fully satisfy one's own needs, electrical energy must have a number of quality indicators. The main one is the voltage, which is regulated using the transformer antapf. What is this functional element of power equipment and how it works, we will understand further.
What is antsappa: definition and purpose
Ansapfa of the transformer is a PBV switch located on the high voltage side. Designed to correct the transformation ratio. In a simple sense, the process involves changing the number of turns in the winding, which, according to physical laws, corrects the voltage.
This element allows you to change the voltage level by +/- 10%. The level depends on the power of the power equipment, its technical features. Adjustment of the antapf of the transformer 10/0, 4 kV is carried out only when the equipment is taken out for repair (switching without excitation).
It is not possible to make adjustments at any convenient time, since the operation requires de-energizing subscribers. That is why on powerful transformers of power substations from 110 kV and above, another device is used, called on-load tap-changer.
Voltage regulation under load is considered to be an advanced antapf that allows you to change the number of turns without shutting down. For the comfort of compliance with the modes by dispatching personnel, the on-load tap-changer is supplemented by telemechanics.
Anzapf device
Ansapfa transformer is a simple device in the form of a coiled connection, which is paired with a switch and winding on the high side. Adjustment is carried out in two directions: upward (reduction) and downward (addition). All this is characterized by the physical law of Ohm, which assumes a proportional ratio of resistance to voltage level.
To understand the position of the transformer antapf, you need to look at the symbols on the nameplate. Each step assumes a 2.5% change, up or down. A spring device is used to maintain the stability of the contact resistance.
Note that over time, the insulation resistance may decrease, so the transfer of the devicemust be done at least 2 times a year. Once a year, physical measurements of the windings should be made using a megger or other equipment from the insulation service.
Schematic diagram
Schematic representation of the antapf is shown below. Some transformers may differ in position and direction of movement, other parameters remain unchanged.
On-load tap-changer: how it works
As noted above, the adjustment of the transformer pin can be performed through the tap changer. A special type of switching involves constant voltage adjustment depending on the time of day and load. Regulation is carried out in the range from +/- 10 to 16%. In some cases, a fully automatic mechanism is installed that supports the desired mode of operation on its own. Other options depend on operational control from the control room or the OPU.
As for the principle of operation, it is performed as follows:
- There is an antapf, which changes the number of windings by unscrewing the spring. Under normal conditions, 33 turns implies a change in the number of turns by 1 unit. The degree of regulation is largely determined by the pitch detuning.
- To automate the process, a mechanical motor is connected, which is tuned to perform exactly one operation. From the control panel, a signal is sent to the electric motor, after which the regulation takes place.
- For a faster response, you need to usetelemechanics, which provides the process from the control room.
Types of on-load tap-changers
There are several types of voltage adjustment, among which stands out:
- OLTC with current-limiting reactors. This is an old-style transformer mount, which assumes the presence of two contactors and a reactor. During the operation, the two contacts are short-circuited before changing to another position. A reactor is used to limit the negative impact.
- OLTC with limiting resistors. It is applied at new transformer substations. The method involves a trigger contactor, which involves changing the number of turns through the spring. This reduces the voltage level transformation time and the negative effect on the equipment.
OLTC and remote control: automation of voltage correction
Switching the antapf of a transformer is an extremely important procedure, especially for substations from 110 kV and above. As noted earlier, the process involves the activation of the on-load tap changer, the switching of which can be displayed on the dispatcher's console. For this, telemechanics is used, which is capable of sending a signal to increase or decrease the voltage level via a fiber optic cable.
The general scheme involves the following elements in the chain:
- The presence of a server room that sends and receives a signal to the substation, as well as a computer in the control room. The transfer of information involves the use of a conductor, where most oftenoptical fiber is used. Twisted-pair cases are also common here, but the information transfer rate is significantly inferior.
- At the substation in the telemechanics cabinet, the cable is connected to the block that interacts with the on-load tap-changer. There are two kinds of raise/lower commands at the output. After the operation, a response is given to the server, which manifests itself in the execution or non-execution of the task.
- To determine the voltage level, telemetry is displayed on the computer. When adjusted, the latter should change up or down depending on the signal sent.
Automation and telemechanics provide significant comfort in maintaining regime instructions. Building a system largely depends on the technologies and technical means used. It should be noted that building an automated system of work is the next step in the comfortable regulation of the mode according to the schedule.
Video: mechanical operation of the on-load tap-changer
We invite you to watch a video that shows the mechanics of the on-load tap-changer. Specialists calibrate the adjustment under voltage, counting the number of revolutions completed.
Conclusion
Ansapfa transformer is an element of a power transformer that allows you to adjust the voltage level. The device has a simple mechanism of action based on Ohm's law of resistance. The general principle of adjustment involves changing the number of turns of the winding, however, the process is carried out with or without repayment of the PBB through the tap changer.
The choice depends on the power equipment, its power andsome other features. Adjustment of the antapf of the transformer 10/0, 4 in most cases is carried out only with repayment. For high-voltage substations, where a large number of subscribers are expected to have no electricity, an on-load tap-changer is used. The quality of electrical energy largely depends on such a simple device, which was discussed in the presented article.
