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DC
FIELD TESTING
 KERITE
RECOMMENDED DC FIELD TEST
VOLTAGES
The table below provides the recommended
DC field test voltages for Kerite cables rated 600V through 138kV.
Test values are based on cable rated voltage and are provided for
new installations less than 5 years old, and for over 5 years old
in dry environments. For cables over 5 years old in wet environments,
contact the factory for recommendations.
Column 3 lists
test voltages to be used shortly after a cable installation has
been completed.
Column 4 lists
maintenance DC test voltages that may be used during the first five
years after installation for cable above or below grade.
Column 5 lists
maintenance DC test voltages that may be used for cables installed
above grade, dry locations, five or more years after installation.
Column 6 covers
cables installed below grade, wet locations, five or more years
after installation and recommends anyone contemplating DC Testing
should consult the factory first.
DC
Field Test Voltages
Shielded and Non-Shielded Cables
Refer
to IEEE Standard 400 dated 1991 or later for additional details.
| (1) |
(2) |
(3) |
(4) |
(5) |
(6) |
| |
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DC FIELD
TEST VOLTAGES (kV - Conductor to Ground)
Maintenance Test Voltages |
Rated
Voltage
kV rms
(phase-
to-phase) |
System
BIL
kv
(peak) |
New
Installations |
First
5 Years
After Installation |
5
Years or more
After Installation |
Any
Location |
Any
Location |
Above
Grade
Dry Location |
Below
Grade
or Wet Location |
| 0.6 |
|
10 |
8 |
8 |
C |
| 2.0 |
|
20 |
16 |
16 |
O |
| 2.5 |
60 |
25 |
20 |
20 |
N |
| |
|
|
|
|
S |
| 5 |
75 |
35 |
25 |
25 |
U |
| 8 |
95 |
40 |
30 |
30 |
L |
| 15 |
110 |
55 |
40 |
40 |
T |
| |
|
|
|
|
|
| 25 |
150 |
80 |
60 |
60 |
F |
| 35 |
200 |
100 |
75 |
75 |
A |
| 46 |
250 |
120 |
90 |
90 |
C |
| |
|
|
|
|
T |
| 69 |
350 |
170 |
125 |
125 |
O |
| 84 |
425 |
200 |
150 |
150 |
R |
| 115 |
550 |
226 |
170 |
170 |
Y |
| 138 |
650 |
240 |
180 |
180 |
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The above table
lists the recommended DC installation and service test voltages
for Kerite cables. Make certain that the ends of cables are clean,
disconnected from any apparatus, and positioned to minimize surface
leakage current and corona. Care should be taken to prevent generation
of very high stress by accidental flashovers at terminals or sudden
grounding after the test. The voltage should be reduced to 1/4 of
full value by discharge through a resistor before solid grounding.
Conductors should be grounded for minimum durations equal to twice
the test time.
Caution:
When testing non-shielded cables, ground any metallic objects
in the vicinity of the cable being tested to prevent voltage pickup.
Field testing
is primarily a go, no-go test. The measured leakage current is very
dependent on temperature and unless terminals are properly prepared
and/or guarded against surface leakage and corona, the value recorded
may have little relation to the true leakage through the insulation.
Refer to IEEE Standard 400 dated 1991 or later for additional details.
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