Electrical power runs almost everything on a modern ship, from propulsion motors and thrusters to pumps, cranes, navigation equipment and accommodation services. Marine engineers therefore need confident command of electrical network and machine calculations. This course builds that confidence through a structured, calculation-focused approach. It starts with the component laws for resistors, capacitors and inductors and the reasons sinusoidal supplies are used, then develops phasors, RMS values and power relationships. It moves on to balanced three-phase systems in star and delta, including starting methods and the consequences of connection faults, before showing how to extract efficiency, torque, pole count, slip and equivalent-circuit values from machine nameplate data. The course closes with transformer equivalent circuits and the no-load and short-circuit tests used to determine their parameters.
Course at a glance: Duration 20 hours · Self-paced online · 6 sections, 30 lessons, a 121-page downloadable course book
What you will learn
- Apply Ohm’s law and the capacitor and inductor laws to AC and DC circuit calculations.
- Use phasors, RMS values and the power triangle to analyse AC networks, including parallel RLC circuits.
- Calculate line and phase quantities and three-phase power in star and delta connections.
- Explain star-delta starting and the effect of reconnecting windings at the wrong voltage.
- Derive efficiency, torque, pole count, synchronous speed and slip from machine nameplate data.
- Size power factor correction and interpret equivalent circuits for synchronous and asynchronous machines.
- Determine transformer equivalent-circuit parameters from no-load and short-circuit test results.
Inside the course: a high-level summary, section by section.
AC and DC networks
The course begins with the component laws that govern every electrical network. Resistors obey Ohm’s law, while capacitors and inductors relate current and voltage through rates of change, which gives them very different behaviour under DC and AC supplies. A capacitor blocks steady DC once charged but passes alternating current; an inductor does the reverse. Understanding these laws is the foundation for all later work on machines and transformers.
The course explains why sinusoidal supplies matter. Sinusoids remain sinusoids when passed through linear components, so AC circuits can be analysed with phasors, rotating vectors that capture both magnitude and phase. RMS values relate alternating quantities to the equivalent heating effect of DC, and complex impedance combines resistance and reactance in one quantity. The power triangle links active power, which does useful work, reactive power, which is exchanged with magnetic and electric fields, and apparent power, which determines the current the supply must carry. The sign of the phase angle matters as much as its size: whether current lags or leads tells you whether a load is inductive or capacitive.
Balanced power in three-phase systems is introduced by showing that the time-varying terms in the instantaneous power of the three phases cancel, leaving constant total power. That smoothness is one reason three-phase systems are used for motors and generators. A complete method for a parallel RLC network, from waveform to power triangle, consolidates these skills, followed by exam-style AC and DC practice.
Three-phase systems
The second section deals with star and delta connections. In a star connection, line current equals phase current while line voltage exceeds phase voltage by a factor of root three; in a delta connection, the reverse applies. Because the impedance of each phase does not change when a machine is reconnected, the applied phase voltage is decisive. Moving a motor from star to delta at the same line voltage therefore raises phase voltage and can cause a large increase in current and power.
This principle is used deliberately in star-delta starting, where a motor is started in star to limit inrush current and then switched to delta for normal running. It is also behind a common fault scenario, where a winding intended for star is accidentally connected in delta, overloading the machine. The course develops a clear calculation sequence: identify the connection, decide which values are line and which are phase, convert to per-phase quantities and then compute currents, power and power factor. Three-phase practice problems apply this sequence.
Machine nameplates
Electrical machines are specified by their nameplates, and the course shows how much information can be derived from them. From rated output, line voltage, line current, power factor and efficiency, you can find the electrical power consumed, losses and nominal torque. The speed relationship is the heart of the section: synchronous speed depends on supply frequency and the number of poles, so the nameplate speed reveals the pole count and whether the machine is synchronous or asynchronous. An induction motor runs slightly below synchronous speed, and the difference, expressed as slip, is an essential operating parameter.
Equivalent circuits translate nameplate data into per-phase models. Depending on machine type and the purpose of the calculation, a parallel or series resistance-inductance representation may be used, and the course explains how to choose and calculate each. Power factor correction shows how capacitors can supply reactive power locally, reducing current drawn from the generators and cables. Machine variants and nameplate practice, together with a worked power factor correction example, complete the section.
Transformers
Transformers are used throughout ship electrical systems to step voltages up or down between generation, distribution and consumers. The course introduces the transformer equivalent circuit, separating the ideal transformation from the elements that represent losses and imperfections. Series resistance and leakage reactance represent winding losses and flux that does not link both windings, while parallel elements represent core losses and magnetising current.
A phasor diagram shows how these elements affect voltages and currents under load. The no-load test, performed with the secondary open, measures core losses and magnetising current and determines the parallel branch. The short-circuit test, performed at reduced voltage with the secondary shorted, measures winding losses and determines the series elements. Practice problems and a worked transformer test example show how to move from measured values to a complete equivalent circuit and then predict efficiency and voltage regulation.
Applying the methods on board
On a ship, these calculations are not academic exercises. They underpin generator loading decisions, motor starting arrangements, cable sizing, protection settings and the investigation of faults. A marine engineer who can move confidently between nameplate data, three-phase quantities and equivalent circuits can check whether a motor is overloaded, understand why a bow thruster trips on start, judge the benefit of power factor correction and interpret transformer test reports from shipyards and service providers.
Why this matters in practice
Electrical systems on ships are becoming larger and more complex, with diesel-electric and hybrid propulsion, high-power thrusters and battery systems increasingly common. Engineers from mechanical backgrounds often need to strengthen their electrical calculation skills to work safely and effectively in this environment, and this course provides a structured route to doing so.
Key takeaways
You leave able to analyse AC and DC networks with phasors and power relations, calculate star and delta three-phase quantities, extract machine performance from nameplates, size power factor correction and determine transformer parameters from standard tests.
How you study
The course is delivered fully online and is self-paced, so you can fit roughly 20 hours of study around professional commitments. Lessons combine clear explanation with examples, diagrams and short interactive checks, and the main sections end with graded quizzes (4 in total) so you can confirm you can apply each method before moving on. A 121-page course book can be downloaded and printed for offline reading and later reference.
Course contents
- AC/DC Fundamentals: Component Laws; Why Sinusoids Matter; Phasors and RMS; Balanced Power; Parallel RLC Method; AC/DC Exam Practice
- Three-Phase Networks: Star Connections; Delta Connections; Accidental Delta Fault; Star-Delta Starting; Three-Phase Practice
- Nameplate Calculations: Reading Nameplates; Efficiency and Torque; Poles and Speed; Equivalent Circuits; Power Factor Correction; Machine Variants; Nameplate Practice
- Transformers: Equivalent Circuit; Loss Elements; Phasor Diagram; No-Load Test; Short-Circuit Test; Transformer Practice
- Summary: Key Takeaways
Who this course is for
This course is for engineering graduates and practising engineers who need a solid grounding in marine electrical calculations, including marine and mechanical engineers working with electric propulsion, ship electrical systems or offshore installations, electro-technical officers and students preparing for electrical engineering examinations. Basic algebra and familiarity with circuit concepts are helpful.
Frequently asked questions
How long does Electrical Networks and Machines for Marine Applications take?
The course is designed for about 20 hours of study. It is self-paced and fully online, so you can spread it over a few weeks or complete it more quickly.
What is covered?
The course is organised into 6 sections with 30 lessons, moving from foundations to applied methods, as summarised above.
Is there material to keep after the course?
Yes. A downloadable 121-page course book accompanies the lessons for offline reading and later reference.
How is progress checked?
Each main section closes with a graded quiz (4 in total). The quizzes test understanding of the concepts and methods explained in the lessons rather than memorisation, and you can review the relevant lessons before attempting them.
Can I record this study for my own professional development?
Yes. The course notebook includes a self-assessment of the course objectives before and after study, a reflection page and a learning log, which you can use to keep your own record of professional development.
Duration: 20 hours
Related courses: B07 – Propeller-Engine Matching & Ship Resistance; B01 – Introduction to Marine Engineering & Naval Architecture; B02 – Marine Engineering 1; B10 – Onboard Noise and Vibration
Enrol
Study at your own pace and work through the full course material, worked examples and section quizzes. Enrol in B03 – Electrical Networks and Machines for Marine Applications →
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