MIL-HDBK-1004/10

where

R

= electrolyte-to-anode resistance

V

P = electrolyte resistivity

L = anode length

K = shape function

For 2- by 60-inch anodes:

R

= 22/5(0.0234) = 0.103 ohms

V

c)

Weight of anodes required:

W = YSI

where

W

=

weight of anodes required

Y

=

10 years

S

=

1 lbs/A yr (includes efficiency factor)

I

=

14.7 A current required

W

=

10 x 1 x 14.7 = 147 pounds

Each 2- by 60-inch anode weighs 44 pounds, thus ten anodes would

have a life significantly longer than 10 years.

d)

Resistance of dc circuit:

The resistance for ten widely spaced anodes is

1/R = 1/0.103 + 1/0.103 + 1/0.103 + 1/0.103 + 1/0.103 + 1/0.103 + 1/0.103

1/0.103 + 1/0.103 + 1/0.103

R = 0.010 ohms

Resistance of feeder conductor:

200 feet of HMWPE Size #4 (0.254

ohms per M feet) (refer to Table 10):

R = 0.254 x 0.2 = 0.05 ohms

e)

Sizing of rectifier:

Requirements:

dc current - 14.7 A

Anode circuit resistance - (0.01 + 0.05) = 0.06

dc voltage = IR+3 = (14.7 x 0.06) +3 = 3.882 (say 4)

A standard rectifier in this range has an output of 18 A at 4 V. Figure 88

shows a typical installation of impressed current anodes on a pier structure.

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