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ETL 1110-9-10(FR)
5 Jan 91
Copolymer of chlor-tri-fluorethylene and ethylene
(Halar)2
To
protect
the
insulation
itself
and
to
facilitate
handling,
cables
for
deep
anode
groundbeds also have an outer jacket of high-
molecular weight polyethylene extruded over the
Kynar or Halar insulation.
c)
Since
the
tank
bottoms
are
bare,
their
resistance-to-earth
is
considered
negligible,
therefore, RC is taken as zero.
d)
Calculate total circuit resistance
(RT)
from
equation 1-3:
RT
= RN + RW + RC
RT
= 0.470 + 0.116 + 0.0
RT
= 0.586 ohm
This is well below the design requirement and,
therefore, this groundbed with 6 - 1/4 in. by 6 ft
ceramic anode rods with total backfill column
length of 111 ft will be used.
7) Calculate rectifier voltage (VREC) from equation 1-17:
VREC = (I) (RT) (120%)
Where:
I =
35 amp (Current requirement from step
2, paragraph 2-4b)
RT
=
0.586 ohm (Total circuit resistance
from previous calculation)
120%
=
Rectifier capacity safety factor
VREC =
35 amp x 0.586 ohm x 120%
VREC =
24.6 V
c. Select rectifier.
____________________
2
Registered trademark of Allied Chemical Corp.
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