Comsys – Perfecting Power

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Guarantee THD compliance for your vessel

The benefits of using ADF Power Tuning on a ship or rig are many, including:

  • Less hassle during retrofits
  • Doubled mean time between failures
  • Reduced running cost
  • Lower capital expenditures


THD compliance and common issues

It’s no secret that ships operate on weak grids with large dynamic loads. Common power quality problems for ships, harbor cranes, and marine vessels are reactive power, imbalances, flicker, and harmonics—which can cause power failures and damage sensitive equipment.

A unique challenge for the marine industry is meeting the class requirements that define strict rules regarding harmonics. This is complicated by the increased use of variable-frequency drives (VFD), which are commonly used to conserve energy, but, as a side effect, enhance harmonics. In the past, the common low harmonic solution has been to compensate large loads individually through the use of AFE drives or multipulse drives with a phase-shifting transformer, but these solutions are unnecessarily heavy and complicated.

Six advantages for you

1. Seamlessly meeting standards

The ADF product range has been certified according to most marine standards, such as DNV GL, ABS, and BV.


Additionally, these regulatory bodies mandate THD (total harmonic distortion) limitations for operating vessels. Non-compliance comes with heavy fines or even a demand to cease operations. The highly dynamic capabilities of ADF technology make this solution ideal for achieving THD limits.

2. Take advantage of standard six-pulse drives

ADF Power Tuning can be applied to the main bus bar. Because of this, all loads in the systems can use standard six-pulse drives. There is no longer a need for different types of front end units.

Six pulse drive

Standard six-pulse drives are less expensive and easier to source and service—not to mention reliable. Combined with the modular structure of ADF Power Tuning, we enable dependable redundancy.*

*By using multiple modules and the multi-master functionality, ADF Power Tuning enables you to maintain significant compensation, even if one power module fails.

3. Simplify your THD mitigation

By applying a stack of filter modules on the main bus bar, we eliminate the need for THD compensation on individual drives. And the modular central filtering units keep the harmonics on the bus bar within class requirements.

4. Double the mean time between failure of large drive functions

With ADF Power Tuning, you can expect your MTBF (mean time between failures) to double. Unlike AFE (active front-end drives), ADF Power Tuning is connected in parallel (in shunt) with the drive on the bus bar, making drive function completely unaffected even in the face of a filter failure.

With ADF Power Tuning, you can expect your MTBF (mean time between failures) to double.

5. Save fuel

A typical MPSV (multi-purpose supply vessel) consumes about 4,500 – 7,000 tons of fuel per year. The efficiency of typical diesel electric propulsion indicates that about 5% in losses occur through the active front-end (AFE) drives or multi-pulse drives.

If ADF Power Tuning is implemented, the losses of energy compared to AFE are 30%-40% lower. And with reduced energy demands comes decreased fuel consumption.

If ADF Power Tuning is implemented, the losses of energy compared to AFE are 30%-40% lower.

6. Minimize hassle when retrofitting drive equipment

A common problem when installing drives on an existing vessel is the increase in harmonics on the ship’s grid. This can be especially disruptive because the grid is often not sized for such changes in electrical loads. Additionally, there is often a space constraint, making it challenging to fit conventional low harmonic drives, particularly large AFE drives.

While the common solution to this issue has been to use AFE drives or multi-pulse transformers for large loads, with ADF Power Tuning, the filter is decoupled from the drives. This makes it possible to be placed anywhere and greatly simplifies installation, providing flexibility in decision-making and space-utilization.

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Feel free to download the pdf about Comsys ADF Technology
Feel free to download the pdf about Comsys' ADF Technology.