Cressall

Marine & Offshore

Air cooled resistors for marine and offshore electrical drives

Air cooled resistors: 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.

Recirculating Marine Braking resistors

The closed air/closed water (CACW) system can be used within a braking resistor to limit the braking resistor energy absorbed by the resistor being transmitted into the surrounding machinery room where an increase in ambient temperature could have detrimental cooling effects on other installed equipment.

Using CACW can ensure up to 95% of the braking resistor energy is removed from the air and transmitted into the cooling water supply of the ships system over a period of 30 minutes after energy application.

For large vessels, where many Mega Joules are involved, preventing this energy going into the ambient air can limit the air changes per hour required in the machinery room, keeping the room as close to its normal temperature level as possible.

Closed air closed water recirculating dbr.

The Cressall closed air/closed water recirculating dynamic braking resistor installed in Royal Navy warships.

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:

  • Total continuous power: 200kW – 1500kW
  • Maximum number of electrically separate sections: 14
  • Voltage rating: 800V DC or 690V 3 phase AC
  • Elements: Mineral insulated with Incoloy sheath, test voltage 2.5kV.
  • Cable box: IP56 complete with automatic anti-condensation heater and terminals for one capillary thermostat per section, one PT100 temperature sensor and an airflow sensing switch.

Fan cooled dynamic braking resistor

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