Tunnel Thruster

Designed for easy installation and maintenance. Factory complete with tunnel section

Applicable for Dynamic Positioning and manoeuvring of the most advanced and sophisticated vessels for world-wide operations

Standard or customized Tunnel Thrusters

Brunvoll's portfolio of in-house expertise enables us to develop effective solutions for challenging projects. Our design engineers work together with the yard’s hull design team to achieve cost-effective thruster installations.

  • All Brunvoll Tunnel Thrusters are available in L- and Z-drive configurations
  • Electric motor on bed frame in vertical or tilted position
  • Electric motor on separate foundation with vertical intermediate shaft
  • Brunvoll offers a variety of tunnel extensions

Thruster design with features for heavy duty operations and low life cycle cost

Robust design, generous dimensions, and attention to details make for trouble-free performance.

Brunvoll focuses on excellent technical solutions to ensure that our thruster units can handle all the challenges of the marine environment

  • Replaceable propeller blade bearing liners
  • Various propeller blade materials and designs available
  • Controllable  pitch propeller and fixed pitch propeller versions available
  • Thruster gearbox can be removed from tunnel with propeller blades in place
  • The tunnel is made of thick steel plate reinforced with stiffener rings

Advanced multiple sealing system

  • An advanced multiple sealing system is used for the propeller shaft to provide an ideal environment for the working parts
  • Non-polluting sealing solutions available for use of Environmentally Acceptable Lubricants (EAL). Limited amounts of EAL required
  • The design complies with US EPA Vessel General Permit (VGP)

A variety of Thruster Tunnel options

The Brunvoll standard Thruster Tunnel is a rigid and robust construction with ring stiffeners and a modular motor foundation.

We may also add on a variety of options such as:

  • Extra landing bars adopted to tank top and hull frames
  • Extra ring stiffeners adapted to centre girder
  • Tunnel extensions, either straight cut or cut to suit hull lines
  • Protection grids

Customized solutions – trunk mounted tunnel thruster

  • Thruster unit arranged in a trunk with a bolt in tank top plate
  • Heavy steel structure and bottom guiding arrangement and support by conical studs
  • Reduces the yard’s installation work and responsibility
  • Brunvoll trunk-mounted tunnel thruster unit can be removed for easy service access and repair without dry-docking the vessel

Starter characteristics

Direct On-Line starter

Starting current:

5-10x Nominal motor current (IN)

Pros:

Low price and high starting torque

Cons:

High in-rush current

Description:

The Direct On-Line (DOL) starter consists of a contactor and a protection device such as a circuit breaker. The contactor is energized when the start button is pressed, and the full line voltage is connected to the motor. Motor is started with propeller in zero pitch position (IZP).

Click the images to enlarge

Star-Delta starter

Starting current:

2-3x Nominal motor current (IN)

Pros:

In-rush current reduced with approx. 60% compared with DOL

Cons:

Reduced starting torque

Description:

The star-delta starter method applies reduced voltage to the motor, thus reducing current, during startup. This method requires that both ends of motor winding terminals are available. When connected in star each winding has less voltage (1 / √3 ~ 60%), and thus will have reduced starting current and torque. When full speed is reached the motor is connected in delta, having full torque available. Propeller pitch can be increased, and load applied when motor is connected in delta. Motor is started with propeller in zero pitch position (IZP).

Click the images to enlarge

Auto-Transformer

Starting current:

2-3x Nominal motor current (IN)

Pros:

In-rush current reduced with approx. 60% compared with DOL

Cons:

Reduced starting torque

Description:

Auto-Transformer also applies reduced voltage in steps to the motor during startup. The transformer voltage ratio can be designed to the application, typically having a 50-70% motor voltage during startup. The motor consumes less current at a lower starting voltage. For example, with a 50% tap on the Auto-Transformer, the motor draws half its rated current, or about 25% of what it would draw with a DOL starter. Motor is started with propeller in zero pitch position (IZP).

Click the images to enlarge

Electronic soft starter

Starting current:

2-2,5x Nominal motor current (IN)

Pros:

In-rush current reduced 

Cons:

Reduced starting torque.
Based on electronics

Description:

An electronic soft starter is a starting device that controls the way electricity is provided to the motor by using active switching devices such as thyristors. The device works in both in-line and in-delta configuration modes in three-phase motors. 

This starting method is ramping up the motor voltage in the starting sequence resulting in a reduced start-up current, allowing for a smooth and surge-free increase in motor torque. The voltage dips, stress, and wear and tear on the mechanical parts are all reduced as a result. Due to the thyristors there will be harmonic distortion of the current, and the influence on system voltage will depend on starting current and system impedance. Motor is started with propeller in zero pitch position (IZP).

Click the images to enlarge

Frequency converter starter

Starting current:

0,5x Nominal motor current (IN)

Pros:

In-rush current reduced.
Full speed and torque control

Cons:

THD generated, filters required.
Based on electronics

Description:

This is an electronic-controlled approach for starting asynchronous motors smoothly. It controls the frequency and current for the motor with electronics inverter circuits, avoiding large startup current. The thruster system's mechanical parts will be protected from high load because of the smooth start-up, and the this will also reduce the load on generators during startup compared to line-starter options. Depending on required performance torque and current may be below nominal values during startup. This is the high-end solution for the starting the thrusters, giving benefits such as smooth start, better energy economy, reduced wear and tear and process optimization.  Other benefits include motor speed stability during load changes and a longer motor life overall. Motor is started with propeller in zero pitch position (IZP).

Frequency converter starters may have different interface towards the main switchboard where 6-pulse rectifier is the most common, but both 12/24 pulse and Active Frontend (AFE) are used.6-pulse starters are the most common type, widely used due to the compact design and availability.The disadvantage with the 6-pulse starter is the increased THD during startup, particularly in smaller power system with large thrusters this might be an issue. 

To mitigate the THD a 12 or 24 pulse transformer and rectifier may be chosen, typically used for larger thrusters in larger ships. 
Frequency converter starters with active front end guarantees sinusoidal current and does not require a transformer. The AFE rectifier and LCL filter is more spacious than the 6-pulse rectifier and is suitable for high end solutions and ships with relatively small power system compared to thruster power.

Click the images to enlarge

Complete system deliveries

One source - one responsibility

For optimal performance Brunvoll takes responsibility for delivering complete systems and for providing support throughout the lifetime; from design, production, installation and commissioning, through daily operation.

Ask us for a complete thruster system including:

  • Electric drive motor, asynchronous or Permanent Magnet type
  • Starter or VFD for the motor
  • BruCon Control, Alarm and Monitoring system
  • BruCon Joystick and DP

Compile your vessel from Brunvoll's  product range

The wide product range of Brunvoll gives a unique configuration flexibility of integrated propulsion, manoeuvring and automation systems, see Propulsion Systems.

TUNNEL THRUSTERS

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Contact

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Joar Heggset

Joar Heggset

Sales Manager, Brunvoll AS

+47 916 30 640
joar.heggset@brunvoll.no

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