[BC] Tower Location Change For WLAN 1390

[PeterH]

On Apr 16, 2010, at 6:21 AM, RichardBJohnson at comcast.net wrote:

> In the days when Part 15 was created, circa 1960, the around-town  
> distribution was 2300 volts!

Since almost the beginning, LADWP, my employer, as an EE, in an  
earlier lifetime, has used much, much higher voltages: 4,800 volts  
for general distribution, 34,500 volts for sub-transmission and  
commercial/industrial distribution, and 138,000, 230,000, 287,500 and  
500,000 volts ac and 1,000,000 volts dc for transmission.

Almost all transmission within the city itself is 230,000 volts,  
whether underground or overhead.

> Then, using the same wires and same insulators, the distribution  
> was upped to 4200 volts!

The process is called "Wye-ing up".

Wye-ing up retains the same line-to-ground voltage, hence it can  
retain the same wires, insulators, and spacings.

Changing a 2300 volt ? system to a Wye system would result in the  
voltage being 1.732 * 2300 = 3983, or 4000 volts, not 4200 volts.

A more likely combination would be 4,200 volts for Wye, and 4,200 /  
1.732 = 2424.871, or 2,400 volts for ? .

2,400 volts is one-half of 4,800 volts, LADWP's long-time standard  
for ? distribution.

In fact, all of LADWP's circuits, of whatever type, are ? , not Wye.

Wye lines are generally the result of Wye-ing up, as Wye lines are  
inherently less reliable, as well as being lower in cost, both  
compared to ? lines.

I suspect the present problems with electric distribution and  
transmission system noise, on AM radio, can be traced to inadequate  
maintenance of Wyed-up lines.