[OZAPRS] Problems with APRS in SE Qld

Ray Wells vk2tv at exemail.com.au
Thu Oct 18 07:31:53 EST 2007


Dave Ingram wrote:

>Andrew Rich wrote:
>  
>
>>And what gets me is this.
>>
>>Those owners of the offending digis have installed UI-DIGI.
>>
>>Which has a remote function. You can change the parameters remotely.
>>
>>They stick until you have a power bump.
>>    
>>
>
>Which is happening quite a lot these days with the storms. I don't know
what
>backup power is setup at the digis, but a UPS (even the $100 DSE ones)
might
>be a good investment.
>
>Most outages are 20 seconds when the 11kV feeder has auto-reclose. If the
>wires are on the ground, the lights stay out, but if the problem is a
>lightning strike, windborne debris or wildlife then the 20s pause is
often
>long enough for the problem to go away or fall down.
>
>  
>
Twenty seconds before a reclose seems a long time. We ran five seconds 
with lockout occuring on the third trip, but different authorities have 
different thinking. We ran a nominal 11,000 volts while our adjoining 
neighbour ran 10,500. That only became a problem when a tie between the 
two systems was installed. When I suggested that we run 10,750 on that 
section so that consumers only saw a "one-tap" increase, i.e. 6 volts 
instead of 12, I was reminded of the additional I squared R losses a 250 
volt reduction on the 11kv would cause. Our Chief Electrical Engineer 
was frugal!

Ray vk2tv
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