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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