Download the technical brochure for IEEE bushings. PDF
Download the technical brochure for the IEC bushings. PDF
FGRBLW-Tough Series
Dry Type Paperless RIF® Transformer Bushing up to 345 kV
RIF® provides state of the art technology for bushings: delivering reliable long-term performance, reduced risk, and lower cost of ownership.
Non-oil, non-gas, paperless, non-porcelain, explosion-free, maintenance-free and environmentally friendly
Solid construction – For tough environments
RHM International has pioneered the next generation of bushing technology: resin impregnated fibers wrapped in a condenser graded structure. Unlike previous alternatives, RIF® bushings have a completely solid construction without any insulation paper – with no room within the core structure for water ingress during operation in tough environments. In addition to the lowest risk of failure, RIF® bushings are projected to last longer without the need for costly maintenance or replacement – and with zero risk of explosion. The RIF® bushing’s robust construction provides the utility or transformer manufacturer with the quality and reliability they are looking for in a bushing at a very cost competitive price.
A simple and rigorously controlled production process allowing design flexibility with consistent Quality and one of the best lead times in the industry.
Sound and robust engineering choices
The internal electrical and mechanical stresses of the capacitive core have been decreased significantly by our patented capacitive core internal stress division cushion technology. Our stress-free design significantly improves resistance to cold and heat impulses with a high mechanical load-bearing capacity.
Other direct benefits include very low dielectric dissipation and partial discharge values which remain consistently low once in operation.
Key causes for the accelerated aging of bushings are therefore largely mitigated which results in a reliably longer lifespan.
Silicone Rubber external insulation
As for all of our products, the material of choice for outside insulation is exclusively top quality silicone rubber. Silicone rubber is a growing choice throughout the industry because of its lightweight and pollution resistant characteristics.
Built-in monitoring of core insulation: Tracking the bushing's condition while in operation with LED pre-alarm
The flexible production process of RIF® has allowed RHM to create a built-in large value C2 capacitance (i.e. safe very low voltage across the connection) that acts as a sensor for any leakage current that would be generated by a defective condenser layer. This sensing is connected to an outside LED light that will turn on at a pre-determined leakage current threshold value. The Pre-alarm occurs weeks before such damage could become mission critical for the transformer and require de-energization of the equipment. Concurrently, it is “fool-proof” as the bushing comes operation-ready and does not require any intervention to set up the monitoring before or after installation.
If needed, this same interface can be connected to a control room for continuous monitoring.
Customer benefits:
- Totally safe, no risk of explosion.
- Totally maintenance-free, low cost of ownership.
- Superior resistance to mechanical and thermal stresses.
- Environmentally friendly – no risk of toxic leakage.
- Sealed and impervious to water and pollution.
- Easy storage simplifies grid management
- Built-in monitoring of core insulation condition with early fault alarm fosters full visibility in asset management and avoids emergency situations.
More Information
View our technical papers:
Brochure for IEEE Bushings
Brochure for IEC Bushings
Transformer Bushings FAQs
What is a dry-type transformer bushing?
A dry-type transformer bushing is a high-voltage bushing that does not rely on paper and oil or gas insulation.
What is RIF® insulation?
RIF® is RHM’s proprietary Resin Impregnated Fiberglass insulation system that uses fiberglass thread impregnated with epoxy resin wrapped between capacitive screens to make a finely graded capacitive condenser core. The outer insulation for the RIF® bushing are silicone rubber sheds that are adhered directly to the condenser core. This ensures there is no gap or opening in the overall bushing structure and eliminates the need for filler fluid or material.
How do RIF® transformer bushings reduce operational risk?
RIF® transformer bushings are designed as solid, dry-type, paperless bushings that provide long term electrical (low partial discharge, low dissipation factor) and mechanical performance. Because they do not use oil, gas, porcelain, or insulation paper in the same way as conventional designs, they can reduce risks related to leakage, explosion, water ingress, and maintenance.
What is built-in insulation condition monitoring?
RIF® bushings are considered to be maintenance-free. However, the RIF® bushing can be supplied with an optional built-in insulation condition monitoring system that detects changes in capacitance due to failing capacitive screens to provide an early warning before the issue becomes more serious. An LED sensor mounted on the test tap which is normally lit GREEN indicating normal status will turn to RED indicating a possible deteriorating condition inside the bushing.
Are RHM transformer bushings suitable for tough environments?
RIF® bushings have a proven record of operational reliability at very low and high temperatures. All the required industry standard environmental tests including temperature cycling tests have been performed and passed. RIF® bushings offer the customer an explosion-resistant design with a proven record for reliability under all types of extreme operating conditions from tropical wet, sub-arctic, and desert climates to seismically active zones.
What is the difference between RIS and RIF® Bushings
Even though the RIF® bushing falls within the RIS category of bushings it is a distinctive technology that offers many unique advantages over the RIS bushings currently on the market. The RIF® bushing technology is the more mature bushing technology, introduced to the market in 2003 and having over 24,000 units installed worldwide. The RIS bushing is a relative newcomer which was introduced to the market in 2014. A major difference between RIS and RIF® is how the condenser core is manufactured. The RIS bushing condenser cores are wound with synthetic fabric after which the wound condenser core is encapsulated under vacuum where it is impregnated with epoxy resin, cured and shaped. The RIF® bushing condenser core is made from a continuous wrapping of fiberglass threads that have been impregnated in an epoxy resin bath. There is no casting and full control of every inch being wrapped. The final wrapped condenser core is then heat cured after which it is machined into its final shape. This simpler manufacturing process introduces minimum internal stresses in the capacitive core that can affect the long-term operational life of the bushing while enabling custom designs to be produced with very little impact on the price and lead time.
