PD3060
- Partial
Discharge Detection and Location for MV Cables
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).
Today P.D. diagnostics provides
the Technician with a non-destructive means of eveluating 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 timeously, corrective
measures can be taken before the cable fails thus avoiding Power Failures and
Customer Outages.
