Abyc positive ground isolator8/30/2023 If a motor gets into what is known as a locked-rotor state (meaning the motor is jammed-for example, a centrifugal bilge pump with a piece of trash in the impeller), its current draw can rise sharply, potentially overloading the circuit and/or melting down the pump housing. One situation needs particular attention. In the rest of the world, a conductor's cross-sectional area is typically given in mm² which makes calculations more intuitive. To avoid confusion, the best practice is to use AWG-sized cables in all applications in the U.S. SAE sizing is acceptable in DC circuits, but is not acceptable in AC circuits. For a given conductor size (e.g., 16-gauge), SAE-rated cables have approximately 10% less copper than AWG-rated cables. One is American Wire Gauge (AWG) the other has been developed by the Society of Automotive Engineers (SAE). cable sizes counterintuitive, but there are also two different conductor-sizing formulas using the same numbering system. The European system simply measures the diameter, or cross-sectional area, of the copper in a conductor and uses that. Eventually, the system gets down to 0 and runs out of numbers, at which point as conductors get even bigger the zeros are stacked up (e.g., 00, commonly written as 2/0, or 000, written as 3/0, and so on). conductor sizes are counterintuitive-the bigger the conductor, the smaller the number. These are widely available and not that expensive.Ĭable Sizing: ISO versus ABYC, and AWG versus SAE If a battery system requires a very high AIC rating, Class-T fuses will do the job. (Lithium-ion batteries, for example, may be capable of creating short-circuit currents of tens of thousands of amps.) E-11 provides a table and procedure for determining the necessary AIC rating for that all-important first fuse in a DC system, and for the main breaker in an AC system. The primary fuse on any relatively large battery bank needs to have an AIC rating of at least 5,000 amps and, in some cases, much more than this. The ABYC’s E-11: AC and DC Electrical Systems on Boats has detailed prescriptions. The ABYC requires AC and DC circuit breakers to have a minimum AIC rating of 3,000 amps in most circumstances, and 5,000 amps in some. If the current goes above the AIC level, the device may arc across or form some other conductive path, and fail to do its job. This is typically thousands of amps, and tells us the maximum current the device can safely interrupt if it gets hit by an enormous spike, such as might occur with a dead short across a battery or in the event of a lightning strike. Buried in the small print is another amperage known as the Ampere Interrupting Capacity (AIC). The primary rating for fuses and circuit breakers is the amperage at which they are designed to blow or trip.
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |