150 The N.Z. Journal of Science and Technology. [Mar. 
Table 10. 
Corona Loss. 
Voltage between phases, 66,000; spacing, 6 ft.; size of wire, 7/14; 
diameter, 0-24"; distance, 100 miles; frequency, 50 cycles per 
second. 
- J Symbol. 
Ref. 
Disruptive critical voltage to neutral 
Distance between centres 
Radius of conductor 
Ratio d/a 
Log d/a 
Value of <5 
Value of m for seven-strand cable 
cm. 
cm. 
No. 
No. 
No. 
No. 
183 
0-3048 
600 
6-3959 
1 
0-83 
Vo 
d 
a 
5 
m 
V 0 = 21100 m . 5 . a log _ 
a 
= 21100 x 0-83 x 0-3048 x 6-3969 .. 
Effective voltage between phases 
• • 
• • 
E 9 
Volts 
Volts 
34.200 
59.200 
Vo 
Visual critical voltage 
• . 
• • 
Vi 
V a .. 
No. 
0-552 
4 / a 
0 301 0 301 
1 + = 1 + U dU1 - 1 + 0-545 
Va 0-552 
No. 
1-545 
Value of m for seven-strand cable 
No. 
0-72 
m 
Vi — 21100 x m fl + 0 \ a log ^ 
V va J a 
E 10 
= 21100 x 0-72 x 1-545 x 0-348 x 6-3969 
Effective voltage between phases 
Volts 
Volts 
45,800 
79,400 
V 
Loss through ionization 
* V 5 - 0 00532 x 
d 1 600 
= 0-00552 x 1 .. 
24-5 
0-000225 
c 
Working voltage to neutral 
(V - V 0 ) 2 x 10- 6 = 4000 2 x 10- 6 
W = C . n (V - V 0 ) 2 x 10-6 
= 0-000225 x 50 x 16 per mile per wire 
Loss per 100 miles on three phases 
Volts 
Kw. 
Kw. 
38,200 
16 
* 0-18 
54-0 
V 
E 11 
j 
