Braking resistors bring lasting reliability to marine applications

REO UK has released the cost and space-saving potential of water-cooled braking resistors with a successful vessel project in the marine industry. The company supplied its REOHM series BWD158 water-cooled braking resistor for the design of a luxury vessel, with the resistor capable of ensuring long-lasting safety and reliable performance in a compact, simple-to-integrate footprint.

The vessel features a diesel-electric propulsion system that will give a top speed of 18 knots and a maximum range of 4900 nautical miles. To guarantee that the drive system can safely decrease speed, stop or even reverse throughout voyages, braking resistors are crucial to dissipate unwanted power safely. The new device was selected by the team developing the vessel.

The range of aluminium-clad, water-cooled resistors are manufactured for applications where reliability is vital, even under high loads. The resistor offers an operating voltage up to 1kW and, due to its modular design, maybe parallel and series connected to enable a continuous power dissipation of up to 60kW.

The resistors do not need additional housing as the design is robust and possesses an ingress protection rating of IP65, assuring protection against water jets and all dust. The aluminium housing is anodised to provide corrosion resistance, and all connections and fixings are stainless steel or anodised aluminium to give longevity.

“Developing power electronics for marine or offshore applications is no easy task due to the harsh nature of those environments,” said Steve Hughes, managing director of REO UK. “Accounting for these conditions often involves costly design adjustments, especially with essential components like resistors. In effect, it becomes something of an inconvenient balancing act between cost, size and performance.

“Conventional wire-wound resistors can be used in marine applications, but they are usually housed in separate enclosures, and the windings should be non-corrosive. This usually means that they are larger and more expensive than standard products. When you add to this the complexity of safely water cooling them, the cost of applying them in anything other than the simplest of applications spirals.

“These are all challenges that we overcome with the BWD158. Its robust and IP65-rated design immediately reduces the installation size and complexity, and the in-built safety features — such as the capability to operate coolant free for short periods — ensure that it provides the reliability required at sea. These features make it the ideal choice for marine applications, allowing engineers to forego the balancing act.”