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SarkariResultOutAdditional Assistant Engineer (Electrical) · 2026

Previous Year Question

A synchronized UJT triggering scheme for an SCR is known as __________, and the method of controlling output power by varying the resistor is called __________.
  1. ramp triggering, open loop control
  2. ramp triggering, closed loop control
  3. step triggering, closed loop control
  4. step triggering, open loop control

Correct answer: A

Explanation

A synchronized UJT relaxation-oscillator scheme develops a ramp/sawtooth synchronized to the AC supply and fires the SCR at a controllable point. If firing angle is adjusted only by varying a resistor without output feedback, the control is open loop.

Step-by-step solution

Ramp Triggering and Open-Loop Control explanatory diagram

Correct Answer

A — ramp triggering, open loop control

Explanation

A synchronized UJT relaxation-oscillator scheme develops a ramp/sawtooth synchronized to the AC supply and fires the SCR at a controllable point. If firing angle is adjusted only by varying a resistor without output feedback, the control is open loop.

Key Concept

Ramp Triggering and Open-Loop Control

Exam Point

UJT synchronized firing → ramp; resistor-only adjustment → open loop.

Exam tip

UJT synchronized firing → ramp; resistor-only adjustment → open loop.

Quick method

UJT synchronized firing → ramp; resistor-only adjustment → open loop.