Electric Field Enhancement during Voltage Polarity Reversals in Lapped HVDC Cables.

This paper aims at investigating the effect of fast and slow Voltage Polarity Reversals (VPRs) on the electric field distribution inside the insulation thickness of lapped cables. Two types of lapped cables, i.e., oil-filled cables and Mass Impregnated Non-draining (MIND) cables are investigated. The results show that fast VPRs lead to the greatest field enhancement during the transient. The longer the relaxation period during the slow VPRs, the lesser the fatigue applied on the insulation. Oil-filled cables have greater field enhancement during VPRs, while in MIND cables the transient lasts longer.