Virtual Labs

Characteristics of controlled switching power devices

1. In SCR, the magnitude of latching current (I_L) compared to holding current (I_H) is:

a: Higher Explanation

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b: Lower Explanation

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c: Equal Explanation

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d: Negligible Explanation

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2. The v-i characteristics of SCR is a plot between:

a: Gate voltage (v_g)-vs-Anode Current (i_A) Explanation

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b: Anode-to-Cathode voltage (v_AK)-vs-Anode Current (i_A) Explanation

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c: Anode-to-Cathode voltage (v_AK)-vs-Gate Current (I_g) Explanation

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d: Gate voltage (v_g)-vs-Gate Current (I_g) Explanation

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3. The minimum value of anode current (i_A) below which the SCR turns-OFF is called the

a: Peak anode current Explanation

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b: Latching current Explanation

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c: Holding current Explanation

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d: Forward breakover current Explanation

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4. Under forward blocking state, the three junctions of the SCR (J₁, J₂ and J₃) are in which states?

a: All are forward biased Explanation

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b: All are reverse biased Explanation

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c: 'J₁, J₃' are forward biased while 'J₂' is reverse biased Explanation

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d: 'J₁, J₂' are forward biased while 'J₃' is reverse biased Explanation

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5. A SCR is triggered using a gate current. After sometime the gate signal is stopped. What is the status of SCR?

a: SCR stops conducting. Explanation

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b: SCR goes into reverse breakdown. Explanation

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c: SCR continues to conduct if anode current is maintained above latching current. Explanation

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d: SCR continues to conduct if anode current is maintained above holding current. Explanation

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6. A forward biased MOSFET comes into ON-state by?

a: Allowing Drain current (I_D) Explanation

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b: Applying Drain-to-Source voltage (V_DS) Explanation

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c: Applying Gate-to-Source voltage (V_GS) Explanation

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d: Allowing Gate current (I_G) Explanation

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7. In comparison to IGBT the losses in MOSFET are?

a: Lower Explanation

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b: Higher Explanation

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c: Almost equal Explanation

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d: Double Explanation

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8. Reliable method for firing an SCR is?

a: High dv/dt Explanation

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b: Continuous gate signal Explanation

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c: Firing pulses Explanation

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d: High di/dt Explanation

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9. In practice, the correct method of turning-ON a SCR is?

a: Increasing the anode-to-cathode voltage (v_AK) till it reaches a value equal to or above forward breakover voltage (v_BO). Explanation

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b: The anode-to-cathode voltage (v_AK) is maintained below the breakover voltage (v_BO) and a positive voltage between the gate and cathode (V_g) is applied across SCR. Explanation

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c: Increasing the anode-to-cathode voltage (v_AK) till the anode current (i_A) reaches above holding current (I_H). Explanation

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d: Positive anode-to-cathode voltage (v_AK) automatically turns- ON the SCR. Explanation

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10. How can a conducting SCR be turned-OFF?

a: By application of negative anode current (i_A) or negative anode-to-cathode voltage (v_AK). Explanation

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b: By application of negative gate current (I_g). Explanation

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c: By reducing the gate current (I_g) to zero. Explanation

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d: All of the above methods are correct. Explanation

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11. An IGBT is in ON- state. It is observed that with increasing collector-to-emitter voltage (V_CE) the collector current (I_C) is almost constant. Which region is the IGBT operating in?

a: Cutoff Explanation

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b: Linear Explanation

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c: Saturation Explanation

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d: Reverse blocking Explanation

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12. When compared to MOSFET the time required to turn- OFF an IGBT is?

a: Almost equal Explanation

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b: Lower Explanation

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c: Higher Explanation

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d: Half Explanation

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