Articles: AC Electrical Components

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Forcing A Shore Power Plug to Fit

Putting around peg into a square hole. Why it is a bad idea.

Pros and Cons of a Traditional Isolation Transformer

A marine isolation transformer is a versatile device that can be used to provide galvanic isolation from shore power systems, to enhance electrical safety and eliminate corrosion caused by stray currents. Some isolation transformers can also be used for raising the shore voltage to deal with voltage drop. Another common use is to adapt the vessel’s internal power system voltage to a higher or lower shore power supply. If isolation transformers are so useful why is every boat not equipped with one?

Negative Battery Switching Troubles

We recently had to trouble shoot a problem on a boat that had negative battery switching instead of positive. In North America, everything is switched (and fused) on the positive side of the battery. In Europe, some boats have both positive and negative battery switching (i.e. Beneteau) however, we have never seen a negative only battery switching before.

ELCI Breaker with an Inverter/Charger

Equipment Leakage Circuit Interrupter (ELCI) breakers are fairly new in the North American marine industry. Older boats are not equipped with them however they are now in the ABYC standards for new boats and refits. They are similar to a GFI outlet (like in your bathroom) but they protect the whole boat and trip at a higher level, 30mA instead of 5mA.

Thermal vs. Magnetic Circuit Breakers

Thermal circuit breakers respond to over-current situations, as their name implies, by the circuit generating an inordinate amount of heat causing the bimetal contacts inside the breaker to disengage due to unequal expansion. A magnetic circuit breaker responds to over-current situations by a loading coil inside the breaker lifting the contacts apart when the current flow through the coil is sufficient to overcome the spring force holding the contacts together.

Engine Starter Circuit

A common calamity for which we often get requests for a service call is the engine failing to start or even “turn over”.

Electromagnetic Fields on Your Boat

Electromagnetic forces (EMF) are one of the four fundamental forces in nature, and although they exist naturally, they can also be created. Any wire carrying any amount of electrical current will generate a magnetic field,

Alternators

Early electrical pioneers discovered that passing a magnet in close proximity to coiled wire induced an electrical charge, and that a rotating magnet in front of coiled wire created alternating current. This electrical principle is the basis of an alternator. An alternator is a rotating machine designed to produce alternating current that can then be rectified to produce directional current that can be used, or stored for later use in a battery.

Tachometer Signals

Tachometers all look pretty much the same, but there is some variation between the methods that tachometers get their signal information. The function of a tachometer is to display the RPM (revolutions per minute) of the engine. Typical RPMs will be in the 10s of hundreds, so the method for counting the revolutions must be quick and accurate.

Plugging Into Shore Power

It is easy to become complacent when it comes to plugging an electrical cord into a socket. This convenient arrangement for making an electrical connection has become such a casual part of our lives. It is commonplace to just plug-in if it fits and sometimes, with a little encouragement, it can be made to fit.

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