MIL-HDBK-1004/10
l)
Current division between main and stub anodes:
(1)
Area of tank bottom protected by stub anodes (see
Figure 99):
2
2
As = B(r
-r
)
2
1
where
r
= 13 feet (radius of protected segment)
2
r
= 2.5 feet (radius of riser)
1
A
= 3.1416 (169 - 6.25)
s
A
= 3.1416 x 162.75
s
A
= 511.3 ft
s
(2)
Maximum current for stub anodes:
I = 2.0 x 511.3
Is = 1022.6 mA or 1.02 A
s
(3)
Maximum current for tank bowl = 15.2 A.
(4)
Maximum current for main anodes:
I
= 15.2 - 1.02
m
I
= 14.2 A
m
m)
Rectifier voltage rating:
(1) Electrical conductor to main anodes. Wire size No. 2 AWG,
0.159 ohm/1,000 feet (refer to Table 10), estimated length 200 feet:
R
=
200/1000
x
0.159 = 0.032
(2)
Voltage drop in main anode feeder:
E
=
IR
where
I = 14.2 A
R = 0.032 ohm
E = 14.2 x 0.032
E = 0.45 V
(3)
Voltage drop through main anodes:
E = IR
165
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