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29 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Trigger pulse |
The small amount of power at the gate terminal that allows the SCR to switch and control a large amount of load power. |
Silicon-controlled rectifier |
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SCRs are available with current ratings of: |
.25A - 4000A |
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Holding current (Ih) |
The current necessary to keep the SCR closed. |
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I>T(rms) |
RMS current is maximum rms value of current the Triac or SCR may safely carry |
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V>DRM |
SCR: Maximum peak repetitive forward-blocking voltage. If this is reached or exceeded the SCR will turn on without gate signal. |
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V>RRM |
Triac: breakover voltage that will trigger the Triac into conduction without a gate signal. SCR: maximum peak repetitive reverse-blocking voltage. If this voltage is reached or exceeded the SCR conducts in reverse direction and will be damaged |
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I>H |
Holding current, minimum current required to sustain conduction. |
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V>GT |
Gate voltage needed to produce gate current.(or to turn on triac) |
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I>GT |
Gate current needed to trigger ACT into conduction/ to trigger Triac |
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dv/dt |
Rate of voltage voltage rise that will turn on SCR/Triac without gate signal |
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Operating temperature |
Junction temp range over which the SCR/ Triac may be operated. SCR: range from -40°C to 125°C |
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In most Triacs, how is gate terminal easily identified? |
Smallest lead |
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Voltage drop across Triac when conducting rated current: |
1V to 2V |
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Triac current ratings vary from ____ to ______A |
0.6A to 45A |
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Bidirectional diode thyristor/bilateral trigger diode |
Diac |
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Bidirectional triode thyristor |
Triac |
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Unidirectional device |
SCR |
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2 back to back SCRs do the same job as: |
A Triac |
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A Triac could be triggered into conduction without a gate signal with: |
Breakover voltage |
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One common application for a Triac is: |
Dimmer switch |
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Triacs have (higher/lower) current ratings than SCRs |
Lower |
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Voltage drop across a Triac is: |
1V to 2V |
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A Diac is a ______ sensitive switch |
Voltage |
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When a Diac is triggered, it has (high/low) resistance in (both/one) direction. |
Low, both |
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Typical Power dissipation of a typical Diac is : |
250mW |
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When Diac breaks down and conducts, the voltage drop across the diac is ___-____ |
10V to 15V |
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Diacs are commonly used to trigger a : |
TRIAC |
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Why are UJTs better than Diacs? |
UJTs firing voltage can be altered by changing the voltage across the two base terminals. |
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Firing voltages of UJTs are normally (higher/lower) than those of Diacs |
Lower |
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