Unit 5: Secondary Circuit Flashcards
Which transformer is located in the Secondary Circuit? what type is it?
high voltage step up transformer;
mutual induction;
what does the step up transformer do in the secondary circuit?
converts the low voltage that’s delivered by the autotransformer
x-ray exposures require voltage in the levels of:
kilovoltage
x-ray photon production uses extremely high levels of _______ and extremely small amounts of ________
voltage (kVp);
current (mA)
Power formula:
P = IV
When it comes to a fixed amount of voltage being sent to a transformer, what is the relationship between voltage and current?
as voltage goes up, current goes down and vise versa
on the step up transformer, what side are there more windings on?
the secondary
the primary side is measured in:
the secondary side is measure in:
volts (V);
kilovolts (kV)
the primary current is measured in:
the secondary current is measured in:
amperes (A);
milliamperes (mA)
why does the production of xray photons require AC?
mutual induction wouldn’t work without it
where is the mA meter located?
what does it ensure?
at a center tap on the output of the high voltage step up transformer;
electrical safety
current from a common wall plug is:
60 Hz AC
how many times does current change?
120x each second
AC is required for the process of:
mutual induction
x-ray tube requires a:
DC (electrons flowing in one direction)
what electronic device allows current flow in only one direction?
rectifier
a rectifier is a:
silicon semiconductor
reversal of electrons would be disastrous for the x-ray tube.
true
if electron flow should only be from cathode to anode, the secondary voltage of the high voltage transformer must be _________.
rectified
What is the purpose of the Rectifier Bridge?
to only allow electrons to flow in one direction
What type of device is used to accomplish rectification?
diode
how does a diode allow current flow in only one direction?
by not allowing one half of the current waveform to pass through
what is rectified voltage?
What is “half-wave” rectification and how is it accomplished?
where voltage isn’t allowed to swing negative during the negative half of its cycle.
by doubling the exposure time?
What is “full-wave” rectification and how is it accomplished?
a circuit that rectifies the entire AC waveform;
by cutting exposure time in half and flipping the negatives up
full wave rectification contains at least 4…
diodes
half wave rectification wastes _____ of the power supply, while full wave rectification wastes _____ power
half; no
The High Voltage Generator contains three parts…what are they?
high voltage transformer
filament transformer
rectifiers
single phase power results in a __________ x-ray beam
pulsating
x-rays produced when the single phase voltage waveform has a value near zero are of:
little diagnostic
how do we maximize the energy emitted from the tube in single phase full wave rectification?
three phase power
What is Three-Phase Power and why is it better than Single-Phase?
multiple voltage waveforms are superimposed on each other;
it results in a waveform that has nearly constant high voltage
What type of generator will produce the highest average quality beam?
high frequency generator
what is used in almost all stationary x-ray imaging systems?
full-wave and/or high frequency voltage generators
What is “voltage ripple”?
voltage variation from zero to its max amount
what is the voltage ripple for single phase half and full wave rectification?
100%
what is the voltage ripple for three phase, six pulse:
14%
what is the voltage ripple for three phase twelve pulse?
4%
what is the voltage ripple for high frequency generator?
<1%
What is a “Heat Unit”?
What is the unit of measure for a heat unit?
measurement for thermal energy
Joules (J)
one heat unit =
1 kVp x 1 mAs x 1 second
different generators produce different:
HUs
How would you calculate the HU’s for a single-phase generator?
kVp x mA x seconds
How would you calculate the HU’s for a three-phase or high frequency generator?
1.41 x kVp x mA x seconds
