Xantrex Freedom 30 backfeed question please

When it comes to electrical systems aboard boats, Arild Jensen knows his stuff. Here's where to ask the simplest or most complex questions about marine electrics.

Xantrex Freedom 30 backfeed question please

Postby TheAussies » Sat Nov 19, 2011 1:50 pm

Hello Arild
We'd like to ask you a question concerning backfeed on an Xantrex Freedom 30 Inverter/Charger please.
Our question is: If we accidentally turn on a 30amp breaker that allowed inverted AC power to feed to the Inverter/Charger's AC input line what will happen? Is the Inverter/Charger protected against permanent damage in the event this were to happen?
In our case we think it's important to note that the Inverter/Charger's internal transfer relay is not used. So even though that relay closes when the Inverter/Charger sees AC input power that transferred power is not sent anywhere. In theory then the Inverter/Charger might try to jump to charge mode, but we assume it cannot charge and invert at the same time. So what happens please?
We'll try to describe the electrical set up on our boat. Our main AC panel has four main breakers, 'Shore 1' (bow), 'Shore 2' (stern), 'Generator' and 'Inverter'. Pieces of timber are slid along such that only one of these breakers could possibly be turned on at any one time. There's an Allen Bradley Cat 700-HG42A1 SerA relay in the inverter circuit (2 poles x 30A), with the inverter off that relay in it's NC condition allows L1 and L2 shore or generator AC power to feed to those minor breakers which can be inverter fed, the other minor breakers are fed directly from L1 and L2 (including a minor breaker to feed the Inverter/Charger's AC input). When the inverter is on that relay operates to allow inverter power to feed to the selected L1 and L2 minor breakers (Like 'Galley Outlet' etc.). We have added an arrangement whereby with the flick of a switch (actually two switches, one for each of L1 & L2) we can direct inverter power to the input side of all the minor breakers. That allows us to run our watermaker or water heater etc. whilst we are underway, with our 200A alternator making up the used power. We have tested these things and they work, but of course we have to be careful, to think before we turn stuff on, preferably to wait till our batteries are near fully charged. We have a 1500 Ahr house battery bank (six new Lifeline 8D AGMs), and three 235 watt solar panels. But one risky aspect of what we have done is that it is possible to accidentally turn on our Inverter/Charger's AC input power feed breaker when operating in invert mode, thereby feeding inverter AC power to the AC input side of our Inverter/Charger. What would happen please if we made that error?
Thanks very much from the Aussies Pauline and Rodney Kirk-Burnnand.
'Two By Two' Nova Scotia 47
TheAussies
 
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