Research on a gravity heat pipe for high voltage vacuum interrupter

Recently, development of high voltage vacuum interrupter with large nominal current attracted many interests due to high global warming effect of SF₆ gas. In order to enhance the nominal current, a gravity heat pipe was proposed to be installed as a stationary current-conduction rod in a high voltage vacuum interrupter. The heat pipe is composed of a concentric tube, of which the outer tube is made of oxygen-free copper and the inner tube is made of stainless steel. The bottom of the stainless steel tube was connected to the copper tube by holes. Transient and static thermal performance of the heat pipe was tested, and its thermal resistance was compared with a solid cooper rod with the same dimension. Experimental results show that thermal resistance of the heat pipe is about 1/3 of that of the copper rod, and it decreases slightly with rising of heat flux. Thermal simulation on a 126kV/2000A vacuum interrupter was done respectively when the stationary current-conduction rod is the gravity heat pipe and the copper rod. Simulation results reveal that in the heat pipe installed case, temperature of the contact is 67degC lower than that in the copper rod installed case.