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What is Partial Discharge?
A Partial Discharge is a partial electrical
breakdown in the dielectric material which does not bridge the
dielectric between the conductor and the concentric neutral. The
unit of partial discharge measurement is the Pico Coulomb (pC). The
general factory acceptance criteria for newly manufactured MB XLPE
cables is 5pC.
The PD levels during site
measurements, depend on type of cable, type of
joint/splice/termination. A good PILC oil impregnated may display a
PD level of 100pC. A XLPE dielectric on the other hand could not
continue operating at this level. Dry type terminations may
discharge at 200pC for years without failing (but they will
eventually fail). |
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Today P.D. diagnostics
provides the Technician with a non-destructive means of evaluating
the cable and the accessories. These partial discharge locations
continue to discharge slowly breaking down the dielectric like a
silent cancer. It is just a matter of time, which varies from hours,
to days or even years before the cable or accessory will fail. By
locating these P.D. sites timorously, corrective measures can be
taken before the cable fails thus avoiding Power Failures and
Customer Outages.
Model PD30
consists of the following:
PD Detection and Location for MV Cables Bulletin (PDF) |
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HV Filter +
Coupling Capacitor |
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Rated
Voltage |
33 kV (peak) |
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Rated
Current |
1 Amp |
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Filter
Capacitance |
20 nF |
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Dimensions |
550mm (L) x
660mm (H) x 250mm (D) |
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Weight |
30 kg |
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Calibrator |
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Display
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100-> 10.000 pC |
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Weight |
2 kg |
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Partial
Discharge Detector |
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Display |
Backlit LCD |
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Resolution |
128 x 240 pixels |
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Input Impedance |
10kΩ/50pF |
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Lower Cut-off |
40kHz, 80kHz or
100kHz |
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Upper Cut-off |
250kHz, 600kHz or
800kHz |
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Synchronization |
0.1Hz, 0.02Hz,
0.05Hz |
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Auto Zero
Crossing |
Yes |
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Triggered Noise |
Manual + Auto |
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Dimensions |
250mm (L) x 150mm
(H) x 300mm (D) |
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Weight |
3 kg |
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Software |
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Microsoft
Windows |
9X/NT/2000/XP |
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PD Mapping +
Location |
Yes |
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