in a commutation circuit employed to turn off an SCR satisfactory turn off is obtained when circuit turn off time ______ then device turn off time
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Complete question:
In a commutation circuit employed to turn off an SCR, satisfactory turn-off is obtained when
a) Circuit tum-off time < device tum-off time
b) Circuit turn-off time > device turn-off time
c) Circuit time constant > device turn-off time
d) Circuit time constant < device turn-off time
Answer:
The satisfactory turn-off is obtained when b) circuit turn-off time > device turn-off time .
Explanation:
- SCR is semiconductor controlled rectifier or silicon controlled rectifier which controls the current flowing through the devices.
- SCR is called as thyristor later.
- There are three modes in SCR namely forward blocking mode which is in off state, forward conduction mode which is in on state and reverse blocking mode which is in off state.
- It is used in lamp dimming, motor control and power regulators.
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circuit turn-off time > device turn-off time
Explanation:
The turnoff time of an SCR is specified as the minimum period between the instant the anode current becomes zero and the instant the device is able to block the forward voltage. The process of turnoff is called commutation.
In a commutation circuit employed to turn off an SCR, satisfactory turn-off is obtained when the circuit turn-off time is greater than the device turn-off time.
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