04-10-2009, 04:48 PM
Did anyone else attempt thetrak circuit question this year and discover that the track relay could never pick as:
Vsupply = 50V
Rfeed = 100 Ohm
Ipickup = 500mA,
Given Vsupply and Rfeed, the maximum circuit current could only ever be 500mA, meaning the relay could never pick with ANY additional resistance in the circuit.
I think there must have been a typo, given that the question was asking for the calculation of ballast resistance, did anyone else get stuck doing this question?
I was too far in to attempt a different question, so had to make the most of it. If it was a typo, what is the process now?
Vsupply = 50V
Rfeed = 100 Ohm
Ipickup = 500mA,
Given Vsupply and Rfeed, the maximum circuit current could only ever be 500mA, meaning the relay could never pick with ANY additional resistance in the circuit.
I think there must have been a typo, given that the question was asking for the calculation of ballast resistance, did anyone else get stuck doing this question?
I was too far in to attempt a different question, so had to make the most of it. If it was a typo, what is the process now?