I seem to recall looking at substations down under that incorporate surge counters. In my head they were CTs around the earth conductor with filters to remove leakage and bounce, but I could be wrong. As such they wouldn't be as sophisticated (i.e. accurate) as some integrating device as described by Mike but I presume that when used in sufficient quantity across a fleet - such as a DNO's network - experience will show that for a specific type of location and spec of SPD it's time to consider scheduling replacement after XX events.

Quick Google search throws up these:

www.powerandcables.com/.../

Thanks for the link, those are really interesting. I like the idea that 'we could not be bothered to give you a primary winding and terminals' becomes a design advantage making it easier for the user - and the primary is then an optional accessory.

Clearly this is looking for fairly sizable pulses compared to the domestic SPD - the energy just  to fire the counter itself is probably 10-100 millijoules.  (expecting a fraction of a watt for 10 milliseconds or so on the solenoid to operate the ratchet and increment the mechanism, based on ones I have used elsewhere)
I presume from the sensitivity curve there is some internal diode plus capacitor peak hold/pulse stretcher plus resistive bleed down to generate the clocking voltage. I'm not sure why they chose a 6 digit counter - any pulse that it will survive a million of is no where near worth counting as a significant event...

Still a fun thing.

Do you have a feel for the suggested clock count when a replacement is ordered ?

Mike

No worries (c: And indeed the ones I saw were for EHV circuits with devices sat next to a transformer.

To be fair I'd probably rather route the conductor through a window than have a break in the conductor, given the choice.

mapj1 said:

Do you have a feel for the suggested clock count when a replacement is ordered ?

Not the foggiest, sorry.

Saw them in situ (not the make/model I linked to) and worked them back to some SLDs I had available to confirm what they were and that was as far as I got; they weren't required on our project (as the supply circuit was short and cabled) so didn't get to dig any further. I'd expect the count action threshold would depend on the sensitivity of the counter, the nature of the line, characteristics of the OVPD etc balanced by risk appetite i.e. network-specific experience. They were installed on the terminations of OHLs for circuits spanning large chunks of the NT in Oz so fairly frequent surges I expect.