Firing Angle Of UJT As Oscillator Thyristor Firing Circuit Calculator

Formula Used:

\[ \text{Firing Angle} = \omega \times R_{stb} \times C \times \ln\left(\frac{1}{1-\eta}\right) \]

Angular Frequency (ω):

rad/s

Stablizing Resistance (R_stb):

Capacitance (C):

Intrinsic Stand-off Ratio (η):

Firing Angle (∠α):

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1. What is the Firing Angle of UJT as Oscillator Thyristor Firing Circuit?

The Firing Angle in a UJT (Unijunction Transistor) as Oscillator Thyristor Firing Circuit determines the precise point in the AC cycle at which the thyristor begins to conduct. It is a critical parameter for controlling power delivery in various electronic applications.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \text{Firing Angle} = \omega \times R_{stb} \times C \times \ln\left(\frac{1}{1-\eta}\right) \]

Where:

\( \omega \) — Angular Frequency (rad/s)
\( R_{stb} \) — Stablizing Resistance (Ω)
\( C \) — Capacitance (F)
\( \eta \) — Intrinsic Stand-off Ratio

Explanation: This formula calculates the firing angle based on the circuit's angular frequency, stabilizing resistance, capacitance, and the intrinsic stand-off ratio of the UJT.

3. Importance of Firing Angle Calculation

Details: Accurate firing angle calculation is essential for precise control of thyristor-based circuits, ensuring proper timing for power regulation in applications such as motor speed control, lighting systems, and power supplies.

4. Using the Calculator

Tips: Enter angular frequency in rad/s, stabilizing resistance in ohms, capacitance in farads, and intrinsic stand-off ratio (between 0 and 1). All values must be positive, with the intrinsic stand-off ratio less than 1.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for intrinsic stand-off ratio?
A: The intrinsic stand-off ratio typically ranges from 0.5 to 0.8 for most UJTs.

Q2: How does firing angle affect thyristor performance?
A: The firing angle determines the conduction period of the thyristor, directly affecting the power delivered to the load. A smaller firing angle results in longer conduction time and higher power output.

Q3: Can this calculator be used for different types of thyristors?
A: This calculator is specifically designed for UJT-based thyristor firing circuits. Other thyristor types may require different calculation methods.

Q4: What are common applications of UJT thyristor firing circuits?
A: Common applications include phase control in AC power systems, motor speed controllers, light dimmers, and power regulation in various electronic devices.

Q5: Why is the natural logarithm used in this formula?
A: The natural logarithm accounts for the exponential relationship between the capacitor charging time and the circuit parameters, which determines the firing angle.