The stability of an EPR (ethylene-propylene rubber) compound, used as power cable insulation (138 kV) and for downhole pump (petroleum well) cables, was studied under various conditions of thermal stress. Samples were subjected to temperatures in the 50-300 degrees C range, for periods as long as 1000 h. After these treatments, electric and tensile strengths of the samples were determined, and the samples were also examined by spectroscopic (photoacoustic, infrared) methods. Gases evolved during rubber heating were analyzed by gas chromatography. It was found that: (1) electric strength is reduced: 17% of original value after 1 h at 300 degrees C and 40% after 1000 h at 200 degrees C, but no changes were found after 1000 h at 150 degrees C; (2) paraffin, used as a processing additive in the compound, exudes at temperatures as low as 50 degrees C; the exudate is more oxidized than the input material; (3) Pb/sub 3/O/sub 4/, which is also a constituent of the compound, is reduced to PbO at higher temperatures; and (4) methane is prevalent in the gaseous mixture released by the heated compound.
展开▼
机译：在各种热应力条件下，研究了用作电力电缆绝缘（138kV）和用于井下泵（石油井）电缆的EPR（乙烯 - 丙烯橡胶）化合物的稳定性。将样品在50-300℃范围内的温度下，周期为1000小时。在这些处理后，确定样品的电气和拉伸强度，并通过光谱（光声，红外）方法检查样品。通过气相色谱分析橡胶加热期间进化的气体。结果发现：（1）电力减少：1小时后，在300摄氏度为300℃后，1小时后的原始值为40％，但在150摄氏度下1000小时后没有发现变化; （2）石蜡，用作化合物中的加工添加剂，在低至50℃的温度下散发;渗出物比输入材料更氧化; （3）Pb / sub 3 / O / sub 4 /，其作为化合物的组分，在较高温度下降至PbO; （4）甲烷在由加热的化合物释放的气态混合物中普遍存在。
展开▼
