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my surge protection 'cpd', such as it is...

psychicwarrior
Good morning all


I have obtained the following [I feel as the] 'best we can do for now' information from the DNO. They were helpful in my test case request for info.


"...address 1:

LV underground - 362m

HV underground to primary-  2000m

No Surge protection devices


address 2:

LV underground to substation - 110 m

HV UG from substation to HV pole is 823m then 301m 11kV overhead then 190m HV UG to the primary substation.

Distance to cable termination with surge protection device from secondary substation is 1124m (823m 11kV UG + 301m 11kV Overhead).  The nearest cable

termination does not have surge protection installed. ..."


In relation to the risk assessment equation variables dealing with distribution cable lengths  ie. the Lpal Lpcl Lpah Lpch, how would one fit the given values into the variables ?


For addr1, ignore the HV (e.g. use zero for Lpah Lpch),  then take Lpcl as 362 and Lpal as 638 ?


For addr2, i'm not sure on this one ?


Thanks for your input.

Habs


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  • 0
    Here's a quote from the "BEAMA GUIDE TO SURGE PROTECTION DEVICES":

    Note: SPDs for data communication signal and telephone lines (‘Lightning Barriers’) are fitted into the line (i.e. in series). This introduces a small impedance into the line and a capacitance across the line. For twisted pair signalling below 1MHz, this generally causes no problems. However, at higher frequencies this impedance and capacitance would cause problems. Protectors for these systems need to be specially designed to have lower line capacitance and impedance. For impedance matched systems (e.g. coaxially wired computer networks such as Ethernet) it is essential that the protector is impedance matched, in order to avoid reflections.



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  • 0
    Here's a quote from the "BEAMA GUIDE TO SURGE PROTECTION DEVICES":

    Note: SPDs for data communication signal and telephone lines (‘Lightning Barriers’) are fitted into the line (i.e. in series). This introduces a small impedance into the line and a capacitance across the line. For twisted pair signalling below 1MHz, this generally causes no problems. However, at higher frequencies this impedance and capacitance would cause problems. Protectors for these systems need to be specially designed to have lower line capacitance and impedance. For impedance matched systems (e.g. coaxially wired computer networks such as Ethernet) it is essential that the protector is impedance matched, in order to avoid reflections.



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