Experimental Study on Explosion of Arc Discharge in the Oil Compartment of OLTC

In order to study the pressure propagation properties of the oil compartment of on load tap changer (OLTC) after arc discharge, an arc fault test platform was built, and a large current short circuit test was conducted for a 1:1 oil compartment model. The change curves of pressure and temperature with time at different monitoring points were measured, and the pressure transmission properties in the explosion process caused by arc fault in the oil compartment of OLTC were analyzed. The results show that, the pressure wave generated by arc discharge fault propagates around in spherical form, and the top cover of the oil compartment close to the arc discharge position first reaches the peak pressure of 1.99 MPa at 0.83 ms. Subsequently, the connection structure of the top cover flange began to crack, and the connection structure of the oil compartment tap cover was completely broken at 1.24 ms. Since the discharge in the oil compartment was still continuous after the top cover is broken, the bottom of the oil compartment was also damaged at 40 ms. The connection structure of the oil compartment top cover is one of the weak points of mechanical failure in the case of arc discharge fault, which should be paid more attention in the mechanical strength design of converter transformer.