OPN-10 overvoltage limiter

Surge arrester OPN-10 with polymer insulation (OPNp-10). The advantages of polymer insulation over porcelain include:

  - significantly smaller weight and overall characteristics;

  - simplification of installation;

  - explosion safety;

  - resistance to shock and vibration influences;

  - lack of combat during transportation;

  - high hydrophobicity of the surface;

  - high electrical and discharge characteristics;

  - resistance to climatic factors;

SPECIFICATIONS

Mains voltage class, effective value, kV - 10;

The highest long-term permissible operating voltage (Unr), effective value, kV - 11.5; 11.9; 12.0; 12.7;

Throughput current, A - 300; 400; 550;

Remaining voltage with a current pulse of 1/10 µs, amplitude of 10 kA, kV, not more than - 39.8

Leakage distance, mm - 447;

For the production of the OPN-10 surge arrester polymer case, we made a four-place mold, which allows us to produce surge arresters in a quantity that allows us to fully satisfy the needs of customers.

IMPULSE VOLTAGE

Each electrical installation has insulation corresponding to its rated voltage. The operating voltage applied to the installation may differ from the rated voltage, however, reliable operation is ensured only if it does not go beyond the values of the highest operating voltages. Often the cause of failure of electrical equipment is the presence of voltage pulses.

A voltage pulse is a sharp change in voltage at a point in the electrical network, followed by the restoration of voltage to its original or close to it level over a period of time up to several milliseconds. Voltage impulses arising in electrical networks are divided into switching and lightning.

The energy source of switching voltage pulses is the energy stored in the reactive (inductive and capacitive) elements of the system, which causes the appearance of pulses in transient modes during normal and emergency switching. The values of impulse switching voltages depend on the parameters of the electrical system, the characteristics of the switching devices, as well as the phase of the current at the moment of switching. Lightning surges are caused by lightning strikes into or near an electrical installation.

Switching impulse voltage values can reach 20 kV even in domestic networks. There is no need to talk about the consequences of such an impact on electrical equipment. The situation is often complicated by the fact that in many cases the operation of electrical machines is carried out in difficult conditions (pollution, moisture insulation, frequent starts and stops of units), which makes the insulation of electrical equipment particularly vulnerable due to its accelerated wear and decrease in electrical strength.

VARISTOR AND VOLT-CURRENT CHARACTERISTICS

Valve arresters are used to protect equipment from surge voltages in different countries. However, in recent times, the use of non-linear semiconductor resistors called varistors has been recognized as the most effective (and cheaper) means of protection against impulse voltages of any kind.

Volt-ampere characteristics

A distinctive feature of the varistor is a symmetrical and pronounced non-linear current-voltage characteristic. Due to this, varistors allow you to simply and effectively solve the problems of protecting various devices from impulse voltages. The basic principle of the varistor operation is quite simple: the varistor is connected in parallel with the protected equipment, i.e. during normal operation, it is under the influence of the operating voltage of the protected device. In the operating mode (in the absence of impulse voltages), the current through the varistor is negligible, and therefore the varistor under these conditions is an insulator.

When a voltage pulse occurs, the varistor, due to the non-linearity of its characteristic, sharply reduces its resistance to fractions of an ohm and shunts the load, protecting it and dissipating the absorbed energy in the form of heat. In this case, a current can flow through the varistor for a short time, reaching several thousand amperes. Since the varistor is practically inertialess, after the voltage pulse is extinguished, it again acquires a very large resistance. Thus, the inclusion of a varistor in parallel with electrical equipment does not affect its operation under normal conditions, but it “cuts off” dangerous voltage pulses, which fully ensures the safety of even weakened insulation.

The most widely used are varistors based on zinc oxide, which is due, firstly, to the relative simplicity of their manufacture and, secondly, to the good ability of zinc oxide to absorb high-energy voltage pulses. Varistors are made according to the usual "ceramic" technology, which includes pressing varistors (most often in the form of a disk or washer), firing them, applying electrodes, soldering leads, and applying electrically insulating and moisture-proof coatings. In some cases, this technology allows manufacturers to produce varistors for individual orders.

EXPLOSION PROOF TESTING OF OPN-10 LIMITERS

Before launching OPN-10 surge arresters into serial production, they must be tested for explosion safety. Three surge arresters are tested, two with high current and one with low current. For explosion safety tests, the column of varistors must be shunted with a copper wire with a diameter of not more than 0.5 mm. The diameter of the wire is selected so that the wire burns out before reaching 30 electrical degrees from the moment the electric current appears in the circuit. It is possible to induce an arc without shunting the varistors. A voltage of 1.6 ... 1.7 times the highest long-term permissible operating voltage is applied to the ONP-10 surge arrester, followed by connecting the device to a high current generator. Surge arrester ONP-10, which will be tested, must be fixed in accordance with the operating instructions.

The OPN-10 test surge arrester must be surrounded by a cylinder with a height of at least 0.3 m, with a diameter that is equal to the outer diameter increased by its double height, but not less than 1.8 m.

The test voltage of the surge arrester OPN-10 must be from 0.77 to 1.0 of the rated voltage of the device, but it is allowed to carry out tests at a voltage of less than 0.77 of the rated voltage.

When testing the surge arrester OPN-10 with a high short-circuit current, it is necessary that the effective value of the periodic current component for 0.2 s does not decrease below 75% of the test current value that is expected. The short-circuit power factor should be no more than 0.1.

When testing the surge arrester OPN-10 with a high short-circuit current at a voltage of more than 0.77 of the rated voltage of the device, it is necessary to shunt it with an external conductor. The parameters of the surge arrester circuit are selected so that the power factor is less than 0.1 and the value of the short-circuit current of the periodic component is expected, with a tolerance from zero to plus 20%, for the maximum instantaneous current value was at least 2.6 times greater than the effective values of the periodic component.

After setting the circuit parameters, the outer conductor is removed and the sample is tested. At a voltage less than 0.77 of the rated voltage of the surge arrester OPN-10, it is necessary to withstand in the short circuit, the parameters of which must be selected so that the value of the effective periodic component of the short circuit current flowing through the tested surge arrester OPN-10 is not less than the value specified in the regulatory documentation.

Thus, the maximum momentary value of the short-circuit current should not be less than the value of the effective periodic component than y 1.7 times. When testing the surge arrester OPN-10 with a short-circuit current of a small value, the effective value of the current should be 800 ± 80 amperes, measured after 0.1 s from the moment the short circuit began. Surge arresters ONP-10 can be considered to have passed the test if, during the destruction of the device, all parts remain in the zone limited by the cylinder.

We deliver orders throughout Ukraine, except temporarily occupied territories and war zones. Delivery is carried out by transport and logistics companies chosen by you.

The terms of delivery of the order depend on the availability of goods in the warehouse. If at the time of placing the order, all the selected goods are available, then we will deliver the order within a few days, depending on the remoteness of your region. If the ordered product is not in stock, the maximum delivery time of the order may be several weeks. But we try to deliver orders to customers as quickly as possible, and 90% of customer orders are shipped within the first almost immediately. In the event that part of the goods from your order did not arrive at the warehouse after the specified period during the discussion with the manager, we will definitely inform you about it.

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