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ETL 1110-9-10(FR)
5 Jan 91
e. Calculate number of anodes (N) or length of bare anode wire
(LB).
1)
For required design life
Since ceramic anodes are not consumed during their
life, the quantity of ceramic material beyond that
required to form a coating is not relevant. The number
of
anodes
or
length of
anode wire required
is
determined from the total current required and the
manufacturer's published current rating for a given
life. For rod, strip, tube and disk anodes:
Number of anodes required =
Total current required
(eq l-2a)
Manufacturers rated
current for specific
size, environment and life.
2)
For wire anodes:
Total footage of anode =
Total current requirement
(eq l-2b)
Manufacturers rated current
capacity per foot of wire
for a given environment and
life.
The number calculated will determine the minimum number
of anodes or anode wire length required.
f. Calculate the total circuit resistance (RT).
electrolyte resistance (RN) plus the interconnecting wire
(RC).
RT = RN + Rw + RC
(eq 1-3)
A criterion of 2-ohm maximum groundbed resistance is often
used to limit the rectifier output voltage and the associ-
ated hazards of overprotection. When the total required
current is low, a higher total resistance is often
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