08-06-2010, 01:22 PM
(08-06-2010, 06:53 AM)greensky52 Wrote: Thanks, Peter~But how do you know the addition relay is parallel with the 1st relay, but not in series with the 1st relay?
That is where your underpinning knowldge needs to come in. You cannot expect the question to tell you everything. A feed end relay is connected across the rails in the same what that a normal TR is connected across the rails, so assuming the rail impedance is negligable, the circuit model has them in parallel.