Surge arresters VS Surge protectors
Do you know what’s the different with surge arresters and surge protectors?
Jiangxi Yikai electric tell you the difference of them.
Both the surge arrester and the surge protector are used as originals commonly used in electrical equipment to prevent overvoltage,
especially to prevent lightning overvoltage, but there are still many differences in the application of the two.
Today I will introduce the specific differences between these two types of products.
1. surge arrester
1). surge arrester
Overvoltage limiter.
When an overvoltage occurs, the voltage between the two terminals of the lightning arrester does not exceed the specified fixed value,
which protects the electrical equipment from overvoltage damage; after the overvoltage effect, it can quickly restore the system to the normal state.
2). Valve
Resistors with non-linear volt-ampere characteristics exhibit low resistance during overvoltage.
Thereby limiting the voltage on the lightning arrester, and presenting a high resistance under normal power frequency voltage, can limit the current through the arrester.
3). Rated voltage of lightning arrester
It is the effective value of the maximum allowable power frequency voltage applied between the terminals of the arrester.
The arrester designed according to this voltage can be determined to work correctly under the temporary overvoltage in the specified action load experiment.
It is an important parameter that shows the operating characteristics of the arrester
But it is not equal to the rated voltage of the system.
4). Residual pressure of lightning arrester
When the discharge current passes through the arrester, the maximum voltage between its terminals.
5). Lightning impulse current
An 8/20 wave surge current.
Due to the limitation of equipment adjustment, the actual measured value of apparent Boqian time is 7 ～ 9us,
and the median time of wave tail is 18 ～ 20us.
6). Operation surge current
The apparent wavefront time is greater than 30us and less than 100us,
and the wave tail at the half-peak time is almost an inrush current twice the apparent wavefront time.
7). Square wave impulse current
Shock wave that rapidly rises to the maximum value, remains roughly constant within a specified time, and then quickly drops to zero.
8). Steep wave impulse current
It has an inrush current with an apparent wavefront time of 1us.
9). Inrush current withstand capability (impulse current forcing capacity)
In the case of prescribed waveforms (square wave, lightning, and line discharge, etc.),
the ability of the non-linear resistor to withstand the passing current is expressed in terms of current amplitude and frequency.
10). Action load test
It is used to determine the ability of the arrester to repeat reliably under specified conditions.
The experiment to simulate lightning overvoltage action is called lightning impulse action load test.
The experiment that simulates the operation overvoltage action becomes the operation shock action load test.
11). Protection range of lightning arrester
The maximum allowable length between the lightning arrester and the protected equipment appears,
and the overvoltage on the protected equipment within this range does not exceed the specified value.
12). Continuous current of lightning arrester
The current flowing through the arrester at a continuous operating voltage is expressed as a peak or effective value.
13). Continuous operating voltage of lightning arrester
In operation, the effective value of the power frequency voltage that is permanently applied to the arrester terminals 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 is divided by 2.
15). DC reference current of lightning arrester
The tributary reference current of the arrester is a certain current value near the inflection point of its volt-ampere characteristic curve. The modified value is related to the material and size of the resistance sheet, and its value is about 1 ~ 20mA.
16). Pressure ratio of nonlinear resistors
The ratio of the residual voltage (peak) at the nominal current of the nonlinear resistor to its reference voltage (peak).
17). Pressure release level
Ability of surge arrester to withstand internal fault current. Under the specified short-circuit current, the ceramic pottery with the pressure release device lightning arrester will not explode (that is, the fragments will not fly out of the specified range during the explosion). The pressure release current level is expressed by the effective value of power frequency current.
18). Pollution tolerance
The pollution resistance of the arrester is mainly related to its overall structure. The creepage distance of the outer surface of this set is related to the shape of the umbrella skirt. In addition to the flashover on the surface of this set of surface contamination, it will also cause uneven voltage distribution along the resistor sheet. It can cause partial overheating of the resistance sheet and cause damage. Regular cleaning and application of house paint can also improve the anti-fouling capability of the arrester.
2. the difference between surge protector and lightning arrester
1). In terms of application, it can be divided by 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 less than or equal to 1.2kV, 380, 220 ~ 10V ~ 5V.
2). Different protection objects
Lightning arresters protect electrical equipment, and SPD surge protectors generally protect secondary signal circuits or power supply circuits for electronic instruments and meters.
3). Different insulation level or withstand voltage level
The withstand voltage level of electrical equipment and electronic equipment is not on an order of magnitude.
The residual voltage of the overvoltage protection device should match the withstand voltage level of the protected object.
4). Different installation positions
Lightning arresters are generally installed on the primary system to prevent direct intrusion of lightning waves and protect overhead lines and electrical equipment; SPD surge protectors are mostly installed on secondary systems after the lightning arresters have eliminated the direct intrusion of lightning waves There are no supplementary measures when the lightning wave is eliminated; therefore, the lightning arrester is mostly installed at the incoming line; the SPD is mostly installed at the terminal outlet or signal circuit.
5). Different flow capacity
Because the main function of the lightning arrester is to prevent lightning overvoltage, its relative flow capacity is large; while for electronic equipment, its insulation level is much smaller than that of electrical equipment in the general sense, so SPD is required to protect against lightning overvoltage and operating overvoltage. But its flow capacity is generally not large. (SPD is generally at the end and will not be directly connected to the overhead line. After the current limiting effect of the previous level, the lightning current has been limited to a lower value, so that the SPD with a small flow capacity can completely protect the flow. Value is not important, what matters is residual pressure.)
6). Surge protector is suitable for fine protection of low voltage power supply system.
The power surge protector has a large distance between the terminal equipment and the pre-stage surge protector,
which makes it easy to generate oscillating overvoltages or induce other overvoltages on the line. It is suitable for the fine power surge protection of terminal equipment, and it is used in conjunction with the pre-stage surge protector, the protection effect is better.
7). Different materials
The main material of the lightning arrester is mostly zinc oxide (a type of metal oxide varistor), and the main material of the surge protector is different according to the anti-surge level and graded protection (IEC61312), and is more designed than the ordinary anti-surge The lightning device is much more sophisticated.
8). Technically speaking, the arrester can not reach the level of the surge protector in response time, voltage limiting effect, comprehensive protection effect, anti-aging characteristics and so on.
9). Other insulation levels and the focus on parameters are also quite different.
3. Speaking from the nominal discharge current
The discharge current In of the arrester index ranges from 1.5kV, 2.5kV, 5kV, 10kV, and 20kV. The nominal lightning current of 8 / 20us, the nominal discharge current of the surge protector is from 5kA, 10kA, 0.5kA, 20kA, 30, 20, 120kV.
4. Test standards and requirements are very different
The lightning arrester is connected to the electrical primary system with sufficient external insulation performance, and the appearance size is relatively large, but the surge protector is connected to the low voltage, and the size can be made small. , Ceramics, iron cans, large, heavy weight surge protector with a small amount of silica gel, epoxy package, plastic shell, metal and ceramic, metal and plastic.
5. Place of use
Lightning arresters are mainly used in power stations, lines, distribution stations, power generation, capacitors, motors, transformers, neutral points, steelmaking, and railways. Surge protectors are mainly used in low-voltage power distribution, cabinets, low-voltage electrical appliances, communications, signals, machine stations, and computer rooms.