Capacitive currents occur in high-voltage transmission lines during emergency operation, this happens when one of the phases breaks to the ground. These capacitive currents form an electric arc while destroying the insulation of the suitable cables and the entire relay protection. In order to avoid this, arc suppression reactors are used. They help reduce the effects of the electric arc.
Arc suppression reactor
In modern power supply schemes, numerous protection systems and equipment are used. To avoid interruptions in power supply to consumers, one of the special means of protection for single-phase earth faults is used - arc suppression reactors. They are electrical devices designed to compensate for the capacitive component of the current when shorted to ground.
Reactors are used mainly in networks with insulated neutral voltage from 6 to 35 kV. In networks with voltages from 110 to 750 kV, a grounded neutral is used.
Types and composition of reactors
Arc extinguishing reactors, like any specialized equipment, are divided into some categories.
According to the accuracy of adjustment, reactors are divided into several types:
- uncontrollable - do not have the ability to control, they are made individually according to the specified parameters;
- step-controlled reactors have several specific tuning programs;
- devices with smooth adjustment - this is the most practical type of arc suppression reactors, allows you to select the optimal parameters for better protection.
According to the configuration method, they distinguish:
- with step adjustment with soldering from the main winding; adjustment takes place stepwise - depending on the number of turns;
- plunger allow you to adjust the inductance depending on the location of the core in the coil;
- reactors with additional magnetization have an external source of inductance amplifying the main one.
For management, reactors are divided into:
- Without control. Reactors are quite difficult to maintain; adjusting the inductance in them is usually a lengthy process that involves disconnecting the reactor itself from the network. These are mainly step reactors.
- With a controlled drive. They allow you to adjust the inductance remotely without disconnecting them from the network.
- With automated control. This view allows you to automatically adjust the inductance depending on the operating conditions of the network.
Arc suppression reactors are a conventional transformer. Depending on the conditions, dry and oil-filled are made, with a constant gap between the core and the coil, as well as with a variable one.
Operating principle
In order to avoid interruptions in power supply to consumers, compensation of the active component is used by alignment with the inductive component.
The principle of an extinguishing reactor is based on this. Inductive and capacitive currents are opposite in phase, equal in value, and relative to the energy source are mutually compensated at the point of earth fault, which leads to the attenuation of the electric arc.
This allows you to keep live parts intact, as well as to avoid equipment failure in the event of an earth fault.
The operation of an electric current network with an isolated neutral does not exceed 6 hours, which is enough to find and fix a malfunction on the transmission line. Quick troubleshooting is the key to the stable operation of consumer equipment.
Specifications
In accordance with the rules of technical operation of electrical equipment, extinguishing reactors are used in networks of 6-20 kV when installed on reinforced concrete as well as metal supports, and in all networks above 35 kV at a current of 10 A. They are also used in networks without reinforced concrete and metal supports at voltage for 6 kV and a current of 10 A, as well as 10 kV at a current of 20 A.
Sometimes it is allowed to apply the compensation of the capacitive component with the inductive component in networks of 6-10 kV at a current below 10 A. The rules also indicate that at a ground fault current of more than 50 A, at least 2 reactors are used.
Application
The principle of operation of arc suppression reactors is a modern technological process, provided by digital control systems. This allows you to more accurately and easily remotely adjust the necessary parameters, collect all data on the circuit, archive them and keep statistics. All this makes it possible for the maintenance personnel to carry out the analysis and in the shortest possible time to find and eliminate the malfunction. Arc suppression reactors are very important in protection systems, since an earth fault in an electric current network is the most common type of malfunction.
Compensation of the network by the capacitive component using inductive is a necessary and common measure. A downtime of an enterprise due to a power outage results in large financial losses for it. Therefore, the use of this type of protection is very important.