1the device formed by a P-N junction is called a _
diode
2the negative pole of a battery is connected to the n-type material and the positive pole to the p-type. this is called _
forward bias
3if the polarity of the applied voltage were reversed, with the negative pole of a battery being connected to the p-type, the junction potential would be augmented and no current would flow. this is called _
reverse bias
4type of rectifiers
single and three phase
5types of single phase rectifiers
half wave
full wave
bridge wave
6types of three phase rectifiers
6 pulse - 6 recti
6 pulse - 12 recti
12 pulse recti
7single phase rectifier; electrons flow through the xray tube from the cathod to the anode
when the voltage reverses during the inverse half of the alternating cycle, the rectifier stops current flow
half wave rectifier
8single phase rectifier; both halves of the alternating voltage are used to produce x-rays, so the xray output per unit time is twice as large as it is with half wave rectification
full wave rectification
9this design employs a delta-wound primary transformer with a wye-wound secondary transformer. the output of the secondary windings is rectified with the 6 solid state recti
6 pulse 6 recti
10there are 3 max and min voltages in one complete cycle (1/60 sec). when rectified, there will be 6 positive max voltages per cycle
6 pulse 6 recti
11this circuit is still a 6 pulse circuit
has fixed potential to ground, an advantage over the six-rectifier circuit
6 pulse 12 recti
12looks similar to the 6 pulse, the difference is that the secondary is not a double wye connection; it is a wye and a delta connection
12 pulse recti
13when a delta and a wye winding are connected together in the secondary, the output of the data will lag the wye by 30 degrees. the result of this is that the output of one winding will fill in the ripple of the other
12 pulse recti
14is the variation in the voltage across the xray tube expressed as a percentage of the maximum value
ripple factor
15single phase circuit, the ripple factor is _ because the voltage goes from 0 to a maximum value with each cycle
100%
16a 6 pulse circuit has a ripple factor of _
13.5%
17a 12 pulse circuit has a ripple factor of _
3.5%
18when the 3 phase generators are operated under load, the ripple factor is _
accentuated
19always greater than the theoretical ripple
load ripple factor
20the load ripple factor of the 12 pulse - 3 phase system is about _
5%