Custom Case Study
Installation and operating reliability are critical objectives for remote applications like wind turbines. With lost energy production and high maintenance costs being major issues for alternative energy applications, engineers continue to prioritize improvements to provide long term reliability to the utility companies that operate these wind farms.
Due to their high energy levels, larger sized wind turbines have typically used multiple low voltage tubular AC capacitors in parallel, with a feed-through connection. The connection system for these capacitors is a small M5 screw that is susceptible to vibration forces. In addition, the security of the actual connection can be easily overlooked during the assembly process.
Customers are also keen to avoid using oil-filled capacitors in the electronics system of the turbine, due to the potential damage caused in the event of a failure of the capacitor seal. However, the excellent performance of oil-filled capacitors has been an important factor in their application selection and usage.
To meet these requirements, Vishay ESTA developed a new triangular-shaped LVAC capacitor assembly. This capacitor system contains three 3-phase capacitors (one in each of the three corners) and utilizes a new three-terminal, triangular-shaped connection system.
The capacitor anodes themselves use a dry solid resin that is based on the same natural oil as existing single-anode discrete capacitors, but with an added hardener. This removes liquid oil from inside the capacitor, a key customer goal.
This system also uses a triangular interconnect system with three much larger M10 bolts for connections. These M10 bolts are much less likely to be mis-assembled or visually overlooked when incorrectly attached.
The required base area for a triangular casing is about the same as for three individual tubular capacitors — each with an 84 mm diameter — but the terminal connection area is now more than three times that of individual tubular capacitors. This easily provides sufficient space for the three solid 20 Nm M10 counter-nut bolts, and therefore an improved vibration-proof connection.
If the system requires even higher power levels, the paralleling of such triangular capacitors with feed-through connections is still possible due to the delta-shaped arrangement of the bolts.
Using a solid resin material, based on the previously used oil, offers an additional benefit. The solid structure provides superior heat dissipation and also a fixed and rigid anode winding position inside the triangular form factor. This means the tear-off fuse wires that are attached to the winding elements inside the capacitor are less susceptible to the high vibration forces often seen in oil-filled capacitors used in wind turbine applications. This is a very important benefit, given the high vibration forces that are seen inside the wind turbine.
Please fill out the form and submit to get started.
