 |
 |
| Home> Dynamic braking> Marine braking resistors |
Applications
Electrical drive systems are being used more and more on ships, oil rigs, crane barges and vessels of all types, for every type of powered application: main propellors and bow thrusters, driving winches and windlasses, cranes, lifts, conveyors and jacks, cable laying and tensioning.
Advantages of electric braking
An important benefit from using an electric drive is that reliable systems of regenerative and dynamic braking are available to complement or replace traditional mechanical braking systems. The advantages of electric braking include control, reliability, mechanical simplicity, weight saving and in some cases the opportunity to make use of the regenerated braking energy.
Range
Cressall Resistors’ wide range of resistor technologies and long experience in this field means that we have suitable brake resistor designs for all of the above applications, with braking powers from a few kW up to many MW (needed, for example, for some crane and main propulsion brakes) and cooling methods which include liquid, forced air and natural convection. We have standard products of all types.
Design considerations
The majority of our designs make use of suitably rated Incoloy-sheathed mineral insulated elements. These are less vulnerable to physical damage, prevent accidental contact with live, possibly high, voltages, and are thus considered much safer to use in these environments. Applications in areas of heavy pollution, exposed to flammable liquids or gases, or severely corrosive environments would also justify the use of a sheathed element. Use of marine-grade stainless steels for all metalwork including fasteners and fittings is standard.
For brake resistors operating at more than 2kV, sheathed elements are unsuitable and we employ live elements. Normally, cooling is by simple natural convection, but if the heat losses after braking would impose unacceptable loads on the ship’s air conditioning system we add an air-to-water heat exchanger to transfer the brake energy to the ship’s chilled water system.
 |
| A 1MW fresh water-cooled brake resistor for marine use. |
Fresh water
Most ships have a chilled water system, which circulates cool water throughout the vessel, used for both air conditioning and equipment cooling. It is usually straightforward to incorporate resistors of the type shown into these circuits.
Our standard range has the following features, using vessels, cable box and fittings constructed from 316 grade stainless steel:
Sea water
Construction and ratings as our fresh water designs but with titanium-sheathed elements in higher-grade stainless steel vessels, suitable for continuous duty in hot sea water.
Fan cooled
These units are suitable for deck mounting on their included anti-vibration mounts, with enclosures and all fittings and fan in 316 grade stainless steel:
| Fan cooled brake resistors, power ratings and dimensions | ||||||
|
power (kW, max) |
length mm |
base width mm |
total width mm |
height mm |
fan motor kW |
fan dia. mm |
| 300 | 1888 | 722 | 1098 | 1181 | 3.6 | 710 |
| 600 | 2203 | 1016 | 1341 | 1840 | 7.5 | 710 |
| 1000 | 2950 | 1016 | 1341 | 1840 | 9 | 800 |
| 1500 | 3656 | 1216 | 1541 | 1840 | 18 | 900 |
Air cooled: natural convection
For small inverter drives we offer our standard ES range, intended for indoor use and usually incorporated within or on the roof of the drive system control panels. Standard enclosures are in galvanized sheet steel but optionally 304 or 316 grade stainless. For higher powers we have custom-built designs, optionally with air-to-water heat exchangers to dissipate the brake energy via the ship’s chilled water system.
Cressall Resistors Ltd, Evington Valley Road, Leicester, LE5 5LZ U.K. Tel: (+44) (0)116 273 3633