Electric Azimuth Propulsion

Propulsion Systems for Efficient Propulsion, Positioning and Manoeuvring

Brunvoll's wide product range constitutes a great configuration variety of tailored propulsion systems for all types of vessels

Azimuth Propulsion

The ideal propulsion system for vessels requiring extensive manoeuvring and positioning during main working conditions.

Brunvoll's range of azimuth propulsion units includes pull open and push ducted versions with FP/CP propellers.

We supply complete systems consisting of propulsion units, tunnel thrusters, controls, automation and drives.

Azimuth Pull Open Propellers

A typical system for double ended ferries can be two Brunvoll Azimuth CPP pulling propulsion thrusters in a battery-electric system with a diesel genset for charging of batteries for redundancy purpose.

The Azimuth thruster can be connected to a permanent magnet motor powered by the battery pack, which is normally charged by shore connection.

All system configurations are designed and optimised for the actual vessels. Safety and redundancy is at the highest level to ensure operational uptime regardless of area of operation.

Typical ship types are coastal ferries, offshore support vessels, and other vessels operating in a combination of transit and port mooring.

Azimuth Push Ducted Propellers

An efficient heavy duty propulsion system ideal for vessels with need for efficient bollard pull in towing or pushing operations.

Typical ship types are cable laying vessels, SOVs, tugs and other vessels with requirements to a combination of transit and DP operations.

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
No items found.

Technical Information

Interested in further information about this product?
Download the product sheet available to see more

References

Selected Brunvoll references

No items found.
See all references
Related content

Read more

Related Products

See all products

Contact

Please contact us for any further information you may require about this solution

See all contacts
Arne Tennøy

Arne Tennøy

Sales Manager, Brunvoll AS

+47 916 76 811
arne.tennoy@brunvoll.no
Bernt Rune Riksfjord

Bernt Rune Riksfjord

Sales Manager, Brunvoll AS

+47 911 26 221
Bernt.Riksfjord@brunvoll.no
Per Olav Løkseth

Per Olav Løkseth

EVP Sales, Brunvoll Group

+47 900 27 063
per.olav.lokseth@brunvoll.no

Curious about this product?

Request for information about our solutions, products and services

Send request