In high-voltage transmission lines, capacitive currents occur during emergency operation, this happens when one of the phases breaks to the ground. These capacitive currents form an electric arc, destroying the insulation of suitable cables and all protective relays. To avoid this, arc extinguishing reactors are used. They help to reduce the effect of an electric arc.
Arc-quenching reactor
In modern power supply schemes, numerous protection systems and equipment are used. To avoid interruptions in the power supply of consumers, one of the special means of protection for a single-phase earth fault is used - arc-suppressing reactors. They are electrical devices designed to compensate for the capacitive component of the current in the event of a ground fault.
Reactors are mainly used in networks with isolated neutral voltage from 6 to 35 kV. In networks with voltage from 110 to 750 kV,grounded neutral.
Types and composition of reactors
Arc reactors, like any specialized equipment, are divided into several categories.
According to the adjustment accuracy, reactors are divided into several types:
- unmanaged - do not have the ability to regulate, they are made individually according to the given parameters;
- Step-regulated reactors have several specific tuning programs;
- smoothly adjustable arcing reactors are the most practical type of arc quenching reactors, allowing you to select the optimal parameters for better protection.
According to the setting method, they are distinguished:
- with step adjustment with taps from the main winding; adjustment occurs in steps - 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 bias have a third-party source of inductance amplifying the main one.
According to management, reactors are divided into:
- No control. Reactors are quite difficult to maintain, tuning the inductance in them is usually a lengthy process that involves disconnecting the reactor itself from the network. These are mainly stepped reactors.
- With controlled drive. They allow you to adjust the inductance remotely without disconnecting them from the network.
- With automated control. This type allows you to automatically adjust the inductance innetwork conditions.
Arc reactors are a conventional transformer. Depending on the conditions, they are made dry and oil-filled, with a constant gap between the core and the coil, as well as with a variable one.
Operation principle
In order to avoid interruptions in the power supply to consumers, the active component is compensated by equalizing with an inductive component.
This is the basis of the principle of the arc-quenching reactor. The inductive and capacitive currents are opposite in phase, equal in value, and with respect to the energy source cancel each other out at the earth fault point, resulting in the extinction of the electric arc.
This allows you to keep the current-carrying parts intact, as well as to avoid equipment failure in case of a ground fault.
The operation of the electrical network with an isolated neutral does not exceed 6 hours, which is quite enough to find and fix a fault on the transmission line. Fast troubleshooting is the key to stable operation of consumer equipment.
Features
In accordance with the rules for the technical operation of electrical equipment, arcing reactors are used in networks of 6-20 kV when installed on reinforced concrete and metal supports, and in all networks above 35 kV at a current of 10 A. They are also used in networks that do not have reinforced concrete and metal supports at a voltage of 6 kV and a current of 10 A, andalso 10 kV at 20 A.
Sometimes it is allowed to use compensation of the capacitive component using the inductive one in networks of 6-10 kV at a current below 10 A. The rules also indicate that at least 2 reactors are used when the earth fault current is more than 50 A.
Application
The operating principle of arc quenching reactors is a modern technological process provided with digital control systems. This allows you to more accurately and easily remotely adjust the necessary parameters, collect all data on the closure, archive it and keep statistics. All this makes it possible for the maintenance personnel to analyze and find and eliminate the malfunction as soon as possible. Arc suppression reactors are very important in protection systems, since ground faults in the electrical network are the most common type of fault.
Compensation of the network for the capacitive component using the inductive component is a necessary and common measure. Downtime of the enterprise due to a power outage results in large financial losses for it. Therefore, the use of this type of protection is very important.
