1, according to the principle of work:
(1) Switch type lightning arrester:
Its working principle is that it exhibits a high impedance when there is no instantaneous overvoltage, but once it responds to a lightning overvoltage, its impedance mutates to a low value, allowing the lightning current to pass through. Devices used for such devices include: discharge gaps, gas discharge tubes, thyristors, etc.
(2) Limit pressure type lightning arrester:
Its working principle is that when there is no instantaneous overvoltage, it is high impedance, but with increasing surge current and voltage, its impedance will continuously decrease, and its current-voltage characteristic is strongly non-linear. Devices used for such devices include: zinc oxide, varistors, suppression diodes, avalanche diodes, and the like. Today's surge arresters are mostly limited pressure type.
(3) Shunt type or turbulence type lightning protector
Shunt type: In parallel with the protected device, it exhibits low impedance for lightning pulses and high impedance for normal operating frequency.
Turbulence: In series with a protected device, it exhibits a high impedance for lightning pulses and a low impedance for normal operating frequencies.
Devices used for such devices include: choke coils, high-pass filters, low-pass filters, quarter-wave short-circuiters, and the like.
2, according to use points:
(1) Lightning protection device : lightning protection device for AC power supply, lightning protection device for DC power supply, lightning protection device for special power supply (wind power, solar energy), etc.
(2) Signal lightning protectors : digital signal lightning protection devices, analog signal lightning protection devices, and antenna feeder lightning protection devices.
(3) Combination lightning arresters : SPDs that protect a variety of signals and power supplies at the same time, such as lightning protection devices that integrate video protection against lightning and power supply lightning protection at the camera end in the surveillance system. The lightning protection device that provides both Ethernet signal and power protection at the same time in communication.
3, according to lightning protection points:
Class B SPD: General nominal current is above 30KA. Switch type and pressure limiting type.
Class C lightning protector: The general nominal current is between 15~20KA, all of them are pressure limiting type.
Class D lightning arrester: Generally nominal current is between 5~10KA, all of which are pressure limiting type.
Construction lifts are usually used in combination with tower cranes on the construction site. The general load is 0.3-3.6 tons, and the operating speed is 1-96m/min. There are many types, which can be divided into two types according to the operation mode: non-paired weight and paired weight.
Construction elevator is often used in the construction of manned cargo construction machinery, mainly used in the city high-rise and super high-rise in all kinds of buildings, also known as construction elevator.
Construction Lift,Building Hoist,Construction Elevator,Heavy Duty Lifting Equipment
Jinan Shanghangda Machinery Co., Ltd. , https://www.shdmachines.com