engleski

SHOCK AND VIBRATION OF TRANSFORMER FOR EMU TRAINS

Traction transformers are used for a power supply of EMU (electric multiple unit) or electrical locomotive from the catenary system. They are installed on a vehicle and must be placed in an area defined by the requirements of designers due to customer specifications. Due to 100% low-flow access on the vehicle (new KONCAR’s low floor EMU), transformer is placed on the roof of the train. Transformer consists of active part (magnetic core and windings) and transformer tank (including accessories and cooling unit). The tank holds all transformer mass and through its structure the transformer is fixed to the vehicle. Main transformer is the heaviest single component of the vehicle, therefore its optimization has the utmost importance for designers. Transformer dimensions (volume and weight) must meet severe mechanical constraints of train overall without impairing vehicle’s performance and reliability. This particular unit has total mass of 3460kg and dimensions of 0.8 (H), 2.1 (W) and 2.3 (L) meters. According to the last edition of IEC standard for traction transformers, shock and vibration withstand test is classified as a type test and should be performed on every new transformer design. Numerical analysis was performed by finite element method using parabolic elements with intermediate nodes. Dynamic analysis was performed by using 14 different loading models. Von Mises stresses at the region where maximum values occur are presented for simulated condition that corresponds for the 3g half-time shock directed to the driving direction. Experimental control of numerical results is done by measuring strains during simple pressure probe. At the bottom panel, where maximum displacements occur, the differences were less than 3%. The shaking table of six degrees freedom MASTER (MultiAxes Shaking Table for Earthquake Reproduction) was used as the excitation and processing equipment. During the tests the unit was fixed to the steel platform of the shaking table by means of two plate supports. Every accelerometer was identified for each measuring position by a number. During the tests the unit was in non-operating conditions. Test objective was to analyse the dynamic behaviour of the unit, which was subjected separately along three perpendicular axes (X longitudinal driving direction, Y lateral and Z vertical) to the 15 different dynamic types of loading. Mono-directional excitation tests consisted in resonance search test, simulated long life random test and half shine shock test. Results of the half shine test by 3g pulse excitation during 50ms are shown in control diagram. Time histories of measurements channels 1 and 2 are shown in diagrams. Conclusion Remark: Experimental measurements verified the design numerical simulations and proofed the reliability of the product, important for customer.

transformer; EMU train; stress analysis; vibrations

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