Introduction:

In power transformer applications, a power supply interruption during a tap change is not acceptable, and the transformer is fitted with a more complex on-load tap-changing (OLTC) mechanism. A mechanical tap changer physically makes the new connection before releasing the old using multiple tap selector switches, but avoids creating high circulating currents by using a diverter switch to temporarily place a large diverter impedance in series with the short-circuited turns.

Challenges:

Mechanism analysis of 400 components assembly involving different contacts, springs, joints ,couplers and CAM follower with contacts needs to be simulated using flexible body dynamics was a challenging task.

Scope of Work:

1.All the forces and spring stiffness calculations will be done on the assembly of single module diverter switch by using flexible body dynamics and contact analysis (One phase)
2.The Mechanism should be simulated considering three module assembly diverter switch. (Three-phase)
3.Cam should be designed for 72 Deg rotation in 60ms which is dependent on proper stiffness selection of the pre-compressed spring

Engineering Solution:

Contact force (271N) calculated and deferred 4% with theoretical(280N) calculations. The Proper stiffness of the spring(3.5N/mm) was iterated to achieve 72 Deg rotation in 55.9ms which is below 60ms.