Line A-6 Flashcards
The BJT is considered _______________-controlled while the FET is considered_______________-controlled.
Current, voltage
In contrast to the base-emitter junction of the BJT, the gate-to-source connection of the FET is connected in _______________ bias.
Reverse
Regarding FETs, the resistance between the _______________ and the _______________ is controlled by applying a bias to the _______________
Source (drain), drain (source), gate
When a FET’s gate voltage is zero, the drain current is at _______________
Maximum
As the voltage between a FET’s gate and source increases, the drain current _______________
Decreases
The charge carriers in an N-channel FET are _______________, while in a P-channel FET they are _______________.
Electrons, holes
The IGBT combines the insulated gate aspect of a _______________ with the output performance of a _______________.
MOSFET, BJT
Like the MOSFET, the IGBT is a _______________-controlled device.
Voltage
The IGBT experiences far lower _______________ losses for a given current when in its “on” state than a comparable MOSFET
I^2 R
Unlike the BJT, both the MOSFET and the IGBT can generate complex _______________ through pulse-width modulation.
Waveforms
Often, discrete IGBTs are paralleled together in ______________________________ configurations to form IGBT modules
Darlington-like
Because of its ability to modulate the waveforms of large quantities of power, the IGBT is often a key component of the _________________________________ used to control the large motors of high-traction and high-inertia applications
Variable frequency drives (VFDs)
How is an SCR normally turned on?
By applying a small amount of power to the gate terminal
How does the power-handling ability of the SCR compare to that of a transistor?
SCRs can handle much more power.
How does the quantity of control power needed at the gate of an SCR compare to that required for the base of a transistor controlling the same load?
An SCR requires only a small fraction of the power a transistor would require.
Name two advantages that an SCR has over a mechanical switch.
No contact wear, pitting or corrosion. No contact bounce.
In a stud-type SCR, how does the gate terminal compare in physical size to the anode and cathode terminals?
Gate terminal is the smallest terminal.
In general, how does the physical size of an SCR relate to its current rating?
As current rating increases, physical size increases.
What is likely to happen if the SCR’s current rating is exceeded?
The SCR will overheat and will likely be permanently damaged.
What happens if the SCR’s reverse-blocking voltage is exceeded?
The SCR will conduct in the reverse direction and will be permanently damaged.
What happens if the SCR’s forward-blocking voltage is exceeded?
The SCR will be turned on without a gate signal.
What terminal is commonly tied to the heat sink in the SCR?
Anode
T/F
An SCR is a thyristor, but a thyristor is not necessarily an SCR
True
What happens to an SCR if the current drops below the holding current?
SCR will switch off
