First, the arrester
Overvoltage limiter. When an overvoltage occurs, the voltage between the two terminals of the blaster does not exceed the specified value, which is to protect the electrical equipment from overvoltage damage; after the overvoltage, the system can quickly return to the normal state.
2, valve piece
A resistor having nonlinear volt-ampere characteristics exhibits low resistance at overvoltage. This limits the voltage on the arrester and is high impedance at normal power frequency voltages, limiting the current through the arrester.
3. The rated voltage of the arrester
It is the maximum allowable power frequency voltage applied to the terminals of the arrester. The arrester designed according to this voltage can work correctly under the specified over-voltage in the specified operational load test. It is an important parameter indicating the operating characteristics of the arrester. But it is not equal to the system rated voltage.
4, the residual voltage of the arrester
The maximum voltage between the terminals when the discharge current passes through the arrester.
5, lightning impulse current
An 8/20 waveform inrush current. Due to the limitation of equipment adjustment, the measured value of the time is estimated to be 7 to 9 us, and the median time of the wave tail is 18 to 20 us.
6, operating the inrush current
When the apparent wavefront time is greater than 30us and less than 100us, the wave tail is like the inrush current twice as long as the apparent wavefront time.
7, square wave impulse current
The maximum value rises rapidly, remains substantially constant for a specified period of time, and then quickly drops to a zero-value shock wave.
8, steep wave impulse current
It has an inrush current with an apparent wavefront time of 1 us.
9. Inrush current withstand capability (impact current forced current capacity)
In the case of a specified waveform (square wave, lightning, line discharge, etc.), the varistor is resistant to the ability to pass current, expressed in terms of the magnitude and number of currents.
10, action load test
It is used to determine the ability of the arrester to reliably repeat the action under specified conditions. The experiment of simulating lightning overvoltage action is called lightning impulse action load test. The experiment of simulating the operation of the overvoltage action becomes the operational impact action load test.
11, the protection range of the arrester
The maximum allowable length between the arrester and the protected device appears, and the overvoltage on the protected device does not exceed the specified value within this range.
12. The continuous current of the arrester
The current flowing through the arrester at continuous operating voltage, expressed as a peak or rms value.
13. The continuous running voltage of the arrester
The RMS value of the power frequency voltage that is permanently applied to the arrester terminals during operation is allowed.
14, lightning arrester power frequency reference voltage
The maximum peak value of the power frequency voltage on the arrester measured at the power frequency reference current divided by 2
15. DC reference current of the arrester
The tributary reference current of the arrester is a certain current value near the inflection point of its volt-ampere characteristic curve. The value of the change is related to the material and size of the resistor, and its value is about 1~20mA.
16, the pressure ratio of the nonlinear resistor
The ratio of the residual voltage (peak) at the nominal current of the nonlinear resistor to its reference voltage (peak).
17, pressure release level
The ability of the arrester to withstand internal fault currents. Under the specified short-circuit current, the porcelain pottery with the pressure relief device arrester will not explode (ie, the debris will not fly out of the specified range during the explosion). The pressure release current level is expressed as the effective value of the power frequency current.
18, pollution tolerance
The anti-staining performance of the arrester is mainly related to its overall structure. The creepage distance of the outer surface of the set is related to the shape of the shed. The contamination of the surface of the set, in addition to its surface flashover, can also cause uneven voltage distribution along the resistor. This causes partial overheating of the resistor and causes damage. Regular cleaning and application of the house paint can also improve the anti-fouling ability of the arrester.
Second, the difference between surge protector and arrester
1, the application field can be divided from the voltage level.
The rated voltage of the arrester is <3kV to 1000kV, low voltage 0.28kV, 0.5kV.
The rated voltage of the surge protector is k1.2kV, 380, 220~10V~5V.
2, the protection object is different: the arrester is to protect the electrical equipment, and the SPD surge protector is generally to protect the secondary signal loop or the end of the power supply circuit such as electronic instrumentation.
3. Insulation level or pressure level is different: the withstand voltage level of electrical equipment and electronic equipment is not an order of magnitude, and the residual voltage of the overvoltage protection device should match the withstand voltage level of the protection object.
4. Different installation positions: The arrester is generally installed on the primary system to prevent direct intrusion of lightning waves and protect the overhead lines and electrical equipment. The SPD surge protector is installed on the secondary system, which eliminates lightning waves in the arrester. After direct intrusion, or the arrester does not have the supplementary measures to eliminate the lightning wave; therefore, the arrester is installed at the incoming line; the SPD is installed at the end outlet or signal circuit.
5, different flow capacity: lightning arrester because the main role is to prevent lightning overvoltage, so its relative flow capacity is larger; and for electronic equipment, its insulation level is much smaller than the electrical equipment in the general sense, it is necessary to SPD on lightning overvoltage It is protected by operating overvoltage, but its through-flow capacity is generally small. (SPD is generally at the end and will not be directly connected to the overhead line. After the current limit of the upper stage, the lightning current has been limited to a lower value, so that the SPD with a small flow capacity can fully protect the flow. The value is not important, the important thing is the residual pressure.)
6, other insulation levels, the focus of the parameters, etc. also have large differences.
7. The surge protector is suitable for the fine protection of the low-voltage power supply system. Various AC/DC power supplies can be selected according to different specifications. The power surge protector has a large distance from the front-end surge protector, so that the circuit is prone to oscillating overvoltage or other over-voltage. Fine power surge protection for terminal equipment, combined with the pre-stage surge protector, the protection effect is better.
8. The main material of the arrester is mostly zinc oxide (one of the metal oxide varistor), and the main material of the surge protector is different according to the anti-surge level and the classification protection (IEC61312), and the design is different. Ordinary lightning arresters are much more precise.
9. Technically speaking, the arrester does not reach the level of the surge protector in terms of response time, pressure limiting effect, comprehensive protection effect, and anti-aging characteristics.
Third, from the nominal discharge current:
The arrester current discharge current In is from 1.5kV, 2.5kV, 5kV, 10kV, 20kV. 8/20us nominal lightning current,
The surge protector nominal discharge current is from 5kA, 10kA, 0.5kA, 20kA, 30, 20, 120kV.
Fourth, the test standards and requirements, the difference is very big
Because the lightning arrester is connected to the electrical primary system, it must have sufficient external insulation performance and the appearance size is relatively large, and the surge protector can be made small due to the low voltage. For example, from the appearance volume, the arrester is mainly made of silicone rubber. Ceramics, iron cans, bulky, heavy weight surge protectors with a small amount of silica gel, epoxy, plastic casing, metal and ceramics, metal and plastic.
Fifth, the place of use
Lightning arresters are mainly used in power stations, lines, substations, power generation, capacitors, motors, transformers, neutrals, steel, and railways.
Surge protectors are mainly used in low-voltage power distribution, cabinets, low-voltage electrical appliances, communications, signals, machine stations, and computer rooms.
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