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.
The Cressall closed air/closed water recirculating dynamic braking resistor installed in Royal Navy warships.
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 brake resistors, power ratings and dimensions