Transformer Winding Insulation for Partial Discharge Control
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Solution Overview
Problem
Transformers in medium or high voltage systems face challenges in reducing volume while maintaining reliability, as partial discharges can corrode insulating materials due to ozone and moisture, and existing methods to control partial discharge either increase cost or volume, or compromise power density.
Innovation Solution
A transformer design featuring a magnetic core with a window, where windings pass through without contact, and additional insulating parts on the outer surfaces to reduce electrical field strength and enhance insulation, using silicone rubber paint or gel to increase dielectric constant and prevent partial discharges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the transformer volume is reduced to improve power density, then the power density increases, but the risk of partial discharge increases due to reduced insulation distance
Solution Approach 1:
The patent changes the dielectric parameter by applying silicone rubber paint or gel coating on the winding surfaces. This coating increases the dielectric constant and reduces the electrical field strength in the insulation gap, allowing reduced physical distance while maintaining the same partial discharge resistance. The parameter change from air gap to coated gap enables volume reduction without compromising reliability.
Solution Approach 2:
The silicone rubber paint or gel acts as an intermediary substance between the windings and the air environment. This intermediary layer modifies the electrical field distribution and provides enhanced insulation properties, allowing the transformer to achieve higher power density by reducing overall volume while maintaining adequate insulation performance through the mediating coating material.
2Reliability
If potting material is used to seal the transformer to control partial discharge, then the partial discharge is controlled, but the cost increases and volume increases
Solution Approach 1:
Instead of applying potting material to the entire transformer (global treatment), the patent applies silicone rubber paint or gel coating only on the critical winding surfaces where partial discharge occurs (local treatment). This local quality approach provides the necessary partial discharge control exactly where needed, without the excessive volume and cost penalties of complete potting.
3Reliability
If the distance between windings is increased to reduce electrical field strength, then the partial discharge is controlled, but the transformer volume increases notably
Solution Approach 1:
The patent changes the electrical parameter of the insulation medium by applying silicone rubber paint or gel coating. This coating increases the dielectric constant and reduces the electrical field strength within the existing gap distance, eliminating the need to increase the physical distance between windings. The parameter change allows maintaining compact volume while achieving the same field strength reduction that would otherwise require larger spacing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively reduces the risk of partial discharges between windings and the magnetic core, enhancing the transformer's insulating performance and power density without increasing volume or cost, thereby improving reliability and safety.
Implementation Method 1
the second winding has a first insulating part disposed on an outer surface of the second winding facing the first winding... using silicone rubber paint or gel to increase dielectric constant and prevent partial discharges
Data Source
AI summary
A transformer includes a magnetic core, a first winding and at least one second winding. The magnetic core has a window through which the first winding passes through without contacting the magnetic core. The second winding passes through the window of the magnetic core and is wound on the magnetic core. The second winding has a distance from the first winding, and the second winding has a first insulating part disposed on an outer surface of the second winding facing the first winding.