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ETL 1110-9-10(FR)
5 Jan 91
d)
Calculate total
circuit
resistance
(RT)
from
equation 1-3:
RT = RN + RW + RC
RT = 2.26 + 0.04 + 0 = 2.30 ohms
Since the design requirements call for a maximum
groundbed resistance of 2.5 ohms and RT = 2.30
ohms, the design using fourteen 2-in. by 60-in.
packaged ceramic anodes will work.
8)
Calculate the rectifier voltage (VREC) from equation
1-17:
VREC = (I) (RT) (120%)
Where:
I = 8.2 amp (Current requirement from step 2,
paragraph 2-3b)
previous calculation)
120% = Rectifier voltage capacity design safety
factor.
VREC
= 8.2 amp x 2.30 ohms x 1.2
VREC
= 22.6 V
c. Select rectifier.
Based on the design requirement of 22.6 V and 8.2 amp, a
rectifier can be chosen.
A 12-amp, 24-V unit is selected
because this is the nearest standard commercial size
available.
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