Analysis of deterioration by partial discharge of XLPE using GCMS and FTIR
Deterioration of polymeric dielectrics by partial discharge (PD) might occur at defects in an insulation layer. To elucidate the mechanism of deterioration by PD, measurements were conducted of the gas components produced during deterioration and the substances created on the surface of cross-linked polyethylene (XLPE) samples subjected to PD. Gas component measurements were performed using an experimental apparatus including GC-MS. Results of gas analyses showed that carbon dioxide (CO2) was produced when the XLPE sample is subjected to the PD in a N2+O2 gas atmosphere. The amount of generated CO2 was confirmed to increase concomitantly with the period of voltage application. The FTIR spectroscopic analysis of substances on the surface of deteriorated XLPE revealed carbonyl compounds on the surface of the deteriorated samples. The deterioration was suppressed when a phenolic antioxidant was added: 44-thiobis-3methyl-6tert butyl phenol. The process of deterioration by PD and the effect of the antioxidant on the deterioration by PD were also discussed.
Effects of antioxidants on electrical tree generation in XLPE
The authors have performed experiments at ambient and elevated temperature in order to study the effect of antioxidants and UV absorbers on tree generation in cross-linked polyethylene (XLPE) insulation. On the basis of the experimental results, the inhibition of electrical tree generation by these antioxidant additives is examined in detail, and the mechanism responsible for tree inhibition is discussed.
OPTIMIZATION OF LOW EMITTANCE LATTICES FOR PETRA III
The reconstruction of the existing 2.3 km long storage ring PETRA II into a 3rd generation synchrotron light source (PETRA III) calls for an horizontal emittance of 1 nm rad. In addition the on- and off-momentum dynamic acceptance should be large to ensure sufficient injection efficiency and beam lifetime. We present three different types of lattices for the arcs of PETRA: a so-called TME lattice and a FODO lattice which both are newly designed to reach the specified emittance and the present FODO lattice with damping wigglers. The different lattice types have been compared through tracking calculations, including wiggler nonlinearities. Only the relaxed FODO lattice with damping wigglers meets the acceptance goals.