Nonlinear conductivity and interface charge behaviors between LDPE and EPDM/SiC composite for HVDC cable accessory

Interface charges are easy to accumulate between two different dielectrics with various characteristics, which may cause accelerated degradation of insulation systems. Ethylene-propylene-diene terpolymer (EPDM) is used mainly for HVDC cable joint, which is the most vulnerable part of the cable syste...

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Bibliographic Details
Published in:IEEE transactions on dielectrics and electrical insulation 2017-06, Vol.24 (3), p.1566-1573
Main Authors: Jin Li, Du, B. X., Kong, X. X., Li, Z. L.
Format: Article
Language:English
Subjects:
Accessories
cable accessories
Conductivity
Dielectrics
Direct current
Doping
Electric charge
Electrical resistivity
EPDM
Ethylene
HVDC
HVDC transmission
Insulation
interface charge
LDPE
nonlinear conductivity
Particulate composites
Permittivity
Power cables
Propylene
SiC
Silicon carbide
Space charge
Stresses
Underwater cables
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Summary:Interface charges are easy to accumulate between two different dielectrics with various characteristics, which may cause accelerated degradation of insulation systems. Ethylene-propylene-diene terpolymer (EPDM) is used mainly for HVDC cable joint, which is the most vulnerable part of the cable system because of the interface. Particles with nonlinear conductivity can be doped into the polymer matrix to modify the interface charge behaviors through altering the conductivity under combined stresses. In this paper, silicon carbide (SiC) particles were dispersed into EPDM with 0, 10, 30 and 50 wt% respectively. The space charge behaviors at the interface between LDPE and EPDM filled with SiC particles was measured under 15 and 30 kV/mm. Besides, dielectric constant, dc conduction and trap distribution were introduced to elaborate the suppression mechanism with SiC doping. The SEM results show that the particles are well distributed in the EPDM. The permittivity increases with the fillgrade and the dc conductivity shows an obvious nonlinear trend under various electrical fields. SiC doping can effectively suppress the interface charge accumulation under different stresses. The suppression mechanism is attributed to the nonlinear conductivity and more shallow traps of EPDM/SiC composite. As a consequence, the approximate SiC doped EPDM can availably suppress the interface charge accumulation and offers a possible method for the improvement of cable accessory performance.
ISSN:1070-9878
1558-4135
DOI:10.1109/TDEI.2017.006198