Which Systems Require a Shunt / Current Limiters

[Mark L]

I am currently installing firewall components including some current limiter bases. I have a 60amp B&C alternator and a SD-20 stand-by alternator planned. It is my understanding that I would install a current limiter for each however with 2 different fuses. It is my understanding I would come off the contactor & then bar the 2 together?

I notice that a number of buiders will intall a shunt near this arrangement. Is it correct that this is only for location of an ammeter point and/or is there another purpuse? Which systems require this? I notice most who have intalled this plan on a Dynon EFIS. What about AFS? Garmin? Others?

[shuttle]

Hi Mark,

The current limiter is used in lieu of a CB on the instrument panel and avoids you having to bring the big wire from the alternator all the way to the panel. As long as the limiter is inline between the alternator and the rest of the electrical system you should be fine. You'd have one limiter per alternator (though I've seen some folks have a second limiter covering the path upto the panel).

Yes, the shunt is to provide input to the ammeter. I don't know about others, but AFS uses a shunt for the first alternator but uses an alternative method for the second ammenter - a Hall Effect Transducer. This is described on page 70 of the AFS manual v7.2 available here: http://www.advanced-flight-systems.c...cksupport.html

Steve

[Loboflyer]

Apologies if you already knew this, but it was an 'ah hah' moment for me when I learned about it:

Additionally, the ANLs (limiter) or fuses for each alternator should be closest to wherever they tie into the battery, not closest to the alternator. The reason for this is that the battery is the source of electricity non grata (unwelcome current) if something were to fail in the alternator, for example, a shorted diode, or the wires leading to it.