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## Thyristor firing angle for RC firing circuit Solution

STEP 0: Pre-Calculation Summary
Formula Used
Firing Angle = asin(Gate threshold voltage*((Resistance+Stabilizing Resistance+Variable Resistance)/(Maximum AC input voltage*Stabilizing Resistance)))
α = asin(Vgt*((R+R2+R)/(Vmax*R2)))
This formula uses 2 Functions, 5 Variables
Functions Used
sin - Trigonometric sine function, sin(Angle)
asin - Inverse trigonometric sine function, asin(Number)
Variables Used
Gate threshold voltage - Gate threshold voltage is the minimum voltage required at the gate terminal of an SCR to turn it on. (Measured in Ampere)
Resistance - Resistance is a measure of the opposition to current flow in an electrical circuit. Its S.I unit is ohm. (Measured in Ohm)
Stabilizing Resistance - Stabilizing resistance is to prevent the relay from operating due to saturation of the current during transistors and thyristor start-up. (Measured in Ohm)
Variable Resistance - Variable Resistance is defined as the resistors who resistance can be varied at any instant. (Measured in Ohm)
Maximum AC input voltage - Maximum AC input voltage is the peak of the alternating voltage provided at the input of any electrical circuit. (Measured in Volt)
STEP 1: Convert Input(s) to Base Unit
Gate threshold voltage: 0.5 Ampere --> 0.5 Ampere No Conversion Required
Resistance: 10 Ohm --> 10 Ohm No Conversion Required
Stabilizing Resistance: 5 Ohm --> 5 Ohm No Conversion Required
Variable Resistance: 10 Ohm --> 10 Ohm No Conversion Required
Maximum AC input voltage: 220 Volt --> 220 Volt No Conversion Required
STEP 2: Evaluate Formula
Substituting Input Values in Formula
α = asin(Vgt*((R+R2+R)/(Vmax*R2))) --> asin(0.5*((10+5+10)/(220*5)))
Evaluating ... ...
α = 0.0113638809464693
STEP 3: Convert Result to Output's Unit
0.0113638809464693 Radian -->0.651102417121945 Degree (Check conversion here)
0.651102417121945 Degree <-- Firing Angle
(Calculation completed in 00.016 seconds)

## < 10+ Thyristors Calculators

Excess work due to thyristor 1 in chopper circuit
Excess energy in chopper circuit = 0.5*Reverse di/dt limiting inductance*((Load current of chopper circuit+(Reverse recovery time*Commutation capacitor voltage)/Reverse di/dt limiting inductance)-(Load current of chopper circuit^2)) Go
Worst case steady state voltage across first thyristor in series connected thyristors
Worst case steady state voltage of thyristor 1 = ((Resultant series voltage of thyristor string+(Number of thyristors in series thyristor string-1)*Resistance*Off state current spread of thyristor string))/Number of thyristors in series thyristor string Go
Voltage across first thyristor in series-connected thyristors
Voltage across thyristor 1 in thyristor string = (Resultant series voltage of thyristor string+(Number of thyristors in series thyristor string-1)*Resistance*Off state current spread of thyristor string)/Number of thyristors in series thyristor string Go
Resultant series voltage of series connected thyristor string
Resultant series voltage of thyristor string = Number of thyristors in series thyristor string*Voltage across thyristor 1 in thyristor string-(Number of thyristors in series thyristor string-1)*Resistance*Off state current spread of thyristor string Go
Maximum Thyristor gate voltage for resistance firing circuit
Maximum gate voltage = Maximum AC input voltage*(Stabilizing Resistance/(Stabilizing Resistance+Variable Resistance+Resistance)) Go
Derating factor of series connected thyristor string
Derating factor of thyristor string = 1-(Resultant series voltage of thyristor string/(Number of thyristors in series thyristor string*Worst case steady state voltage of thyristor 1)) Go
Power dissipated by heat in SCR
Power dissipated by heat in SCR = (SCR junction temperature-SCR ambient temperature)/Thermal resistance of SCR Go
Thermal resistance of SCR
Thermal resistance of SCR = (SCR junction temperature-SCR ambient temperature)/Power dissipated by heat in SCR Go
Leakage current of the collector-base junction
Collector to base leakage current = Collector current-Common base current gain of transistor*Emitter current Go
Discharging current of dv/dt protection thyristor circuits
Discharging current of thyristor circuit = Input voltage/((Resistance+Resistance)) Go

### Thyristor firing angle for RC firing circuit Formula

Firing Angle = asin(Gate threshold voltage*((Resistance+Stabilizing Resistance+Variable Resistance)/(Maximum AC input voltage*Stabilizing Resistance)))
α = asin(Vgt*((R+R2+R)/(Vmax*R2)))

## What is an RC firing circuit?

RC triggering circuit consisting of two diodes with an RC network connected to turn the SCR. By varying the variable resistance, triggering or firing angle is controlled in a full positive half cycle of the input signal. During the negative half cycle of the input signal, capacitor charges with lower plate positive through diode D2 up to the maximum supply voltage Vmax. This voltage remains at -Vmax across the capacitor till supply voltage attains zero crossing. During the positive half cycle of the input, the SCR becomes forward biased and the capacitor starts charging through variable resistance to the triggering voltage value of the SCR. When the capacitor charging voltage is equal to the gate trigger voltage, SCR is turned ON and the capacitor holds a small voltage. Therefore the capacitor voltage is helpful for triggering the SCR even after 90 degrees of the input waveform.

## How to Calculate Thyristor firing angle for RC firing circuit?

Thyristor firing angle for RC firing circuit calculator uses Firing Angle = asin(Gate threshold voltage*((Resistance+Stabilizing Resistance+Variable Resistance)/(Maximum AC input voltage*Stabilizing Resistance))) to calculate the Firing Angle, The Thyristor firing angle for RC firing circuit formula is defined as the firing angle at which the thyristor starts conducting. Firing Angle is denoted by α symbol.

How to calculate Thyristor firing angle for RC firing circuit using this online calculator? To use this online calculator for Thyristor firing angle for RC firing circuit, enter Gate threshold voltage (Vgt), Resistance (R), Stabilizing Resistance (R2), Variable Resistance (R) & Maximum AC input voltage (Vmax) and hit the calculate button. Here is how the Thyristor firing angle for RC firing circuit calculation can be explained with given input values -> 0.651102 = asin(0.5*((10+5+10)/(220*5))).

### FAQ

What is Thyristor firing angle for RC firing circuit?
The Thyristor firing angle for RC firing circuit formula is defined as the firing angle at which the thyristor starts conducting and is represented as α = asin(Vgt*((R+R2+R)/(Vmax*R2))) or Firing Angle = asin(Gate threshold voltage*((Resistance+Stabilizing Resistance+Variable Resistance)/(Maximum AC input voltage*Stabilizing Resistance))). Gate threshold voltage is the minimum voltage required at the gate terminal of an SCR to turn it on, Resistance is a measure of the opposition to current flow in an electrical circuit. Its S.I unit is ohm, Stabilizing resistance is to prevent the relay from operating due to saturation of the current during transistors and thyristor start-up, Variable Resistance is defined as the resistors who resistance can be varied at any instant & Maximum AC input voltage is the peak of the alternating voltage provided at the input of any electrical circuit.
How to calculate Thyristor firing angle for RC firing circuit?
The Thyristor firing angle for RC firing circuit formula is defined as the firing angle at which the thyristor starts conducting is calculated using Firing Angle = asin(Gate threshold voltage*((Resistance+Stabilizing Resistance+Variable Resistance)/(Maximum AC input voltage*Stabilizing Resistance))). To calculate Thyristor firing angle for RC firing circuit, you need Gate threshold voltage (Vgt), Resistance (R), Stabilizing Resistance (R2), Variable Resistance (R) & Maximum AC input voltage (Vmax). With our tool, you need to enter the respective value for Gate threshold voltage, Resistance, Stabilizing Resistance, Variable Resistance & Maximum AC input voltage and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.
How many ways are there to calculate Firing Angle?
In this formula, Firing Angle uses Gate threshold voltage, Resistance, Stabilizing Resistance, Variable Resistance & Maximum AC input voltage. We can use 1 other way(s) to calculate the same, which is/are as follows -
• Firing Angle = Angular frequency in radians/sec*((Resistance*Capacitance)*ln(1/(1-Intrinsic stand-off ratio UJT as Oscillator)))
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