Re: Galvanic Isolators
Galvanic Isolators<br /><br />A galvanic isolator is a fairlyinexpensive device installed between the AC safety ground and the DC bonding system that prevents low voltage current leaks from coming aboard via the green line. Installed in series with the grounding wire, the isolatorcombines opposing pairs of diodes that block current due to low voltages, up to about 1.5 volts, which pretty much covers galvanic corrosion. Any higher voltages are allowed to pass retaining the integrity of the grounding wire. Its not perfect, and some isolators are better than others. If the isolator fails in the open position, the danger of electrocution becomes high. A good high quality isolator should be fine, so keep this in mind when you go shopping for one. get one that is rated at least 130 percent of the amperage involved. (40 amps for a 30 amp system.) <br /><br />The ABYC tech commitee prefers the Isolation Transformer. The Isolation Transformer is installed in the shore power supply circuit and it creats a physical barrier within the circuit. Incomin AC power is fed into the primary winding and transferred magnetically to the secondary winding. There is no direct connection between a boats electrical (DC) system, and the shore (AC) system. This is the way to go, no ifs, ands, or butts about it. With both circuits isolated--the green wire stops at the incoming side of the transformer--galvanic current cant pass through. Moreover, AC and DC dont share a common ground, therfore protecting against electrocution. Transformers also negate reverse polarity, and can allow you to use cheaper single pole breakers because you boat will then meet ABYC standards for polarization and protection against shoreside loose wire current anomalies. So why dont we use em? Theyre heavy and expensive.
