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 DEI Marine Galvanic
Isolator Models
DEI Marine Galvanic Isolator Resources
Whenever a boat is connected to shore power,
the hull and drive system is connected to the shore grounding system and to
other adjacent vessels (also connected to shore power) via the grounding
conductor in the shore power cable. This connection, while required for
safety, creates a galvanic corrosion cell involving the dissimilar metals
between boats and between a boat and the shore grounding system, as shown in
the following diagram below:
Four Components are Needed
for Corrosion:
1) Anode – a metal surface which gives
up metal ions (corrodes).
2) Electrolyte – a medium which conducts ionic current between the
anode and cathode.
3) Cathode – a metal surface that picks up metal ions.
4) Metallic Bond – a metallic path that allows current to flow from
cathode to anode.
A simple method which virtually eliminates
this galvanic corrosion problem is to insert an appropriately rated and
certified DEI Galvanic Isolator in series with the grounding conductor of
the ship-to-shore power cable. The function of the Galvanic Isolator is to
provide AC continuity of the grounding conductor (required for safety in the
event of an AC fault) and to block the flow of corrosion-causing galvanic
current.
DEI Galvanic Isolators (GI) are fail-safe,
solid-state DC isolation / AC coupling devices with ratings and
characteristics that significantly exceed those of all known galvanic
isolators designed for marine applications. The proven fail-safe
construction assures that the galvanic isolator never compromises the
integrity of the grounding conductor, even in the unlikely case of the
product failing.
 ABYC
Certified
In the marine industry, the criteria for
galvanic isolators is defined by the American Boat and Yacht Council (ABYC)
Standard A-28, which has a publication date of July 2008 and an effective
date of July 2009. Due to recommendations to the A-28 galvanic isolator
standards committee concerning the need to retain safety grounding under all
conditions, as required by the U.S. National Electric Code for all similar
applications outside of A-28, this standard now makes provision for
fail-safe galvanic isolators.
To be considered "fail-safe," an independent
laboratory must confirm that the isolator will either remain fully
functional or remain a permanent, effective grounding path if it fails when
subject to the maximum current rating. Per the new A-28 standard, galvanic
isolators meeting the fail-safe requirement will not require a monitoring
system since the integrity of the grounding wire will not be compromised
should the isolator fail. All galvanic isolators not meeting the fail-safe
criteria will still require a monitoring system to alert the boat owner that
their grounding system may be compromised.
Fail-Safe
Plus & Fail-Safe Max Technologies
DEI offers a Fail-Safe Plus® (FSP) or
Fail-Safe Max® (FSM) model for each rating except for the 100A and 200A
models, for which only the Fail Safe Max model is offered. Fail-Safe Plus
models not only meet the fail-safe test criteria in the new A-28, but also
have considerably higher fault current ratings than are required and have
very substantial lightning current current ratings, which are not even
required by A-28; hence, the "Plus" designation unique to DEI.
Fail-Safe Max models provide even higher AC
fault ratings than Fail-Safe Plus models and will still be fully functional
when tested to the A-28 fail-safe fault criteria, thereby providing the
ultimate in performance; hence, the "Max" designation. The FSM models will
fail in the safe mode, at a level in excess of the A-28 fail-safe definition
- a point at which the grounding conductor would have previously failed.
DEI Marine Galvanic Isolator Features
& Characteristics
- Fail-safe construction with Fail-Safe Plus™
and Fail-Safe Max™ technology
- Certified to ABYC A-28 July 2008 publication
- Highest AC fault current ratings available
- Ignition protected
- Maintenance-free solid-state design
- Rated for high levels of lightning current
- Very low DC leakage current allowed
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