Partial Discharge & Corona

Why your system needs protection from Partial Discharge

Partial Discharge is the result of a breakdown in the insulation system. Though it usually starts very small, once it begins the deterioration of the insulation system is progressive. When voltage stress reaches a critical level, Partial Discharge will “bloom” and create a Corona. The ionized gas of a Corona is chemically active. In air this generates corrosive gases such as ozone (O3) and possibly nitric acid, causing extreme damage to the magnetic device and related circuit. Eventually, Partial Discharge will cause system failure.

The Partial Discharge Cycle

As voltage stress increases, anomalies in the insulation system will result in Partial Discharge or Corona inception. As voltage stress is reduced, Corona extinction occurs. The Partial Discharge cycle repeats rapidly during the operation of the coil.  Excess energy dissipated during these repeating cycles causes deterioration of the insulation system. The result is premature failure of the coil.

Magnetic devices operating at relatively low voltage levels can exhibit Corona; a localized discharge resulting from gaseous ionization in an insulation system when the voltage exceeds a critical value. That critical value can be exhibited at levels as low as 300V.

Partial Discharge Cycle

BICRON Corona-Free Transformers

Bicron has served customer needs for high-efficiency protection from Partial Discharge for more than 30 years.  Our approach to achieve Corona-Free products is driven by special design protocols and we use proprietary materials developed specifically for this purpose. Our operators and assembly teams are highly trained and every VoltBoss™ series transformer design includes a corona-free level specification. Partial Discharge and Corona-free levels are verified by actual testing.

BICRON's Testing Protocols Verify High-Performance

Applied Voltage or Dielectric Test:
A high AC or DC test voltage is applied between the windings, and from the windings to the ground. The test is designed to verify the adequacy of the system in terms of coupling capacitance (AC) or resistance (DC).
Induced Voltage Test:
The induced voltage test reveals defects that might eventually result in a shorted turn and excessive excitation current. This test is important when winding layers are not insulated.

Partial Discharge (Corona) Test:
The partial discharge test is a nondestructive method of identifying the potential for premature insulation breakdown. The test is capable of detecting small defects in the insulation system that could lead to catastrophic transformer failure. 

Bicron’s VoltBoss™ transformers are designed, constructed and tested to ensure moisture and vibration resistance, heat dissipation, and insulation integrity.  It is our ability to mitigate Partial Discharge that decisively sets us apart from other transformer producers.

Visit our webpage for our VoltBoss™ series high-frequency transformers to learn more about Bicron’s Corona-Free products.

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