SPD Technical Parameter

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Technical Parameter of Surge Protective Devices

>>>Nominal voltage [ Un ]

The nominal voltage of the system to be protected, for ac voltages it is indicated as rms value.

 >>>Rated voltage [ Uc ]

The maximum continuous voltage which may apply on the Surge Protective Devices terminals during the non-conductive state, and also the state to be returned to after surge discharges.

  >>>Nominal current [ IL]

The highest permissible operational current which may be permanently conducted by the load terminals.

 >>>Nominal discharge current  [ In ]

The maximum peak current of 8/20μs wave form, which may be conducted for many events through the SPD terminals.

 >>>Max. discharge current  [ Imax ]

The maximum peak value of surge current 8/20μs, which can be discharged safely by the Surge Protective Device.

 >>>Lightning impulse current [ Iimp ]

A simulated lightning current of 10/350μswaveform, which lightning protective devices can discharge for several times without damage to itself. 

 >>>Voltage protection level [ Up ]

The instantaneous maximum peak voltage across the Surge Protective Device terminals during the surge current discharge.

 >>>Follow current extinguishingcapability [ It ]

The maximum rms main follow current(brought on by the surge current discharge),which may be extinguished by the Surge Protective Device at the presence of Uc

>>>Short-circuit withstand capability

With upstream backup fuse, the maximum short-circuit current which the Surge Protective Device can withstand. 

 >>>Combined impulse [ Uoc ]

It is generated by a hybrid generator(1.2/50μs, 8/20μs) with a virtual  2Ω, the open-circuit voltage of the generatoris defined as Uoc , it is mainly used for Surge Protective Devices Class III.

 >>>Operating temperature range [ Tu ] (Nominal temperature range)

The temperature range where the devicescan be normally used.

 >>>Response time [ tA ]

Response time mainly characterize the response performance of the surge protective devices.The response times could change within a certain limits,depending on the steepness du/dt of theimpulse voltage or di/dt of the impulsecurrent.

 >>>Data transmission speed [ Vs ]

It indicates how many bytes are transmitted at one second (unit: bps), it is the reference value for selecting the correct Surge Protective Device at data transmission system, and is determined by the transmission mode. The data transmission speed is deduced by the frequency bandwidth,in the information system the theoretical relation between the transmission and the frequency bandwidth is: Vs=2fG (Vs=1.25fG in practical application)

>>>Bandwidth [ fG ]

Bandwidth defines the frequency-against performance of a Surge Protective Device,bandwidths are frequencies causing an insertion loss (a ) E of 3dB under certain condition.

 >>>Return loss [aR ]

Return loss indicates at high-frequency applications, forward & reflective ratio ofthe wave at the protective device.
 >>>lnsertion loss [ aE ]

Insertion loss is defined by the relation of the voltage value before and after the insertion of the Surge Protective Device at a given frequency.


Personal lightning protection

– When lightning occurs

1. Stay indoors and close the doors and windows.If you are working outdoors, you should take shelter under a building.

2. Do not use TV, music center etc. without lightning protective devices. Do not touch the water taps. If it is not equipotential bonded.

3. Keep away from conductor or similar metal devices, such as antenna, water pipe, steelgrid,metal door and window, external walls of buildings. Unless they are all equipotential bonded.

4. Do not use telephone, if it is not protected for lightning strike.

5. Keep away from water or other open ground and look for a shelter. Do not swim or doother sports in the water, and do not play ball games outdoors.

6. Do not stand at the top of mountain or building. Do not touch other object with good electrical conductivity.

7. Do not deal with the flammable material in the open container.

8. Keep away from the trees and masts when you are in the wilderness.

9. Do not hold an umbrella or golf clubs across your shoulders in open ground.

10. Do not ride a motorcycle or a bicycle in open ground, especially in wet weather.