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Wrenches, What are you using when you need a shunt larger than the standard 500A/50mV? The application: four Sunny Islands and a Radian in a large grid-tie with backup system. Total current flow through B- is rated 850A (using 125A SI DC breakers) or 1,050A (using 175A DC breakers) on a single large battery bank. Given uncertain continuous amperage, I should use a 1,000A shunt or even a 1,200A shunt, as Deltec recommends never exceeding 67% of a shunt's current rating for long. Deltec makes both; see http://www.deltecco.com/MKC-DC.html. The shunt will be installed inside of a Nottagutter-8, with a Midnite shunt bus on each side. The shunt will be used with the Sunny Island master to control overall SOC and charging parameters; there's no plan for a Tri-Metric in this system, as a Sunny Webbox will handle online monitoring per the customer's wishes. The 1,000 and 1,200A series MKC Deltec shunts are the same physical dimensions as the common 500A/50mV units. However, the larger units are still 50mV. Ralph Heisey of Bogart Engineering, in his "Information on Shunts" reference article (http://www.deltecco.com/MKC-DC.html), tells us to match the ratio of voltage drop to current - that is, just as a 500A shunt drops 50mV, a larger shunt with 1,000A flowing through it should drop 100mV. But all of the larger Deltec shunts are still rated 50mV. Who has done this and resolved the issue? What shunt did you use? Thank you, Allan --
Allan Sindelar al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder and Chief Technology Officer Positive Energy, Inc. 3209 Richards Lane (note new address) Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com
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