e. A tap from L2 is fused by F2 and becomes L2P. Then it goes through circuit
breaker CB27, becomes L2F, and through another normally closed pole of Re-1 on the
other side of the coil for Re-20.
f. Depressing the MAINS push-button switch will apply the incoming line voltage
to Re-20, closing its contacts, and supply the autotransformer with incoming power.
Inside the MAINS push-button switch is a lamp which illuminates when the switch is
g. Autotransformer taps A3 and A14 supply the auxiliary power transformer with
a constant 240vac. Taps A4 and A13 supply 128vac for the fluoro-kvp control.
h. Lead AC is the common of the major kvp selector switch and connects to one
side of the 0.375Ω (3/8Ω) damping resistor. A portion of this resistor is shunted by
contactor Re-24. When low ma stations (below 200ma) are selected, the full
0.375Ω-resistor is inserted in series with P2 lead to the high-tension transformer to
prevent "ringing" in the high-tension waveform. When either 200-ma or 300-ma stations
are selected, contactor Re-24 is closed and only 0.075Ω is inserted.
i. When the autotransformer is energized, 115vac is generated, which closes
relay Re-1. The coil of relay Re-20, main contactor, now transfers to the normally open,
now closed poles of Re-1 which are supplied via T1A and T2L with 240vac.
j. The kvp selection is via leads A1 and A15 from the autotransformer. Lead
AM at this point supplies voltage to the silicon-controlled rectifier (SCR) timer contactor
for radiographic exposures. This output of the SCR timer contactor supplies P1 to the
high-tension transformer. Leads AC and AM in conjunction with circuit breakers CB23
and CB24 supply the kvp meter circuit.
k. The autotransformer is connected to the major kvp selector via taps A1
through A13, and to the minor kvp selector via taps A14 through A20. All voltages from
the autotransformer can be measured at the terminals of the major and minor kvp
selectors. The following table lists the autotransformer terminals and the voltage at that
terminal with respect to terminal A14.
AC to AM = 288vac
A1 = N/A
A6 = 204vac
A11 = 119vac
A16 = 5.6vac
A2 = 272vac
A7 = 187vac
A12 = 102vac
A17 = 8.5vac
A3 = 255vac
A8 = 170vac
A13 = 85vac
A18 = 11.3vac
A4 = 238vac
A9 = 153vac
A14 = 0vac
A19 = 14.1vac
A5 = 221vac
A10 = 136vac
A15 = 2.8vac
A20 = 17.0vac
All voltages should be within 2 percent.