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| import numpy as np | |
| import matplotlib.pyplot as plt | |
| import streamlit as st | |
| # Define the calculation function | |
| def calculate_relay_curve(tr_kva, tr_volt, ct_pr, ct_sec, fac, tms, i_f_fac, curve): | |
| # Calculate transformer current | |
| tr_curr = round(tr_kva / (tr_volt * np.sqrt(3)), 3) | |
| pick = round(fac * tr_curr / ct_pr, 3) # Pickup value in multiples of In | |
| i_f = round(i_f_fac * tr_curr * fac, 3) # Fault current in amps | |
| # Select curve coefficients based on relay type | |
| if curve == 'IEC Normal Inverse': | |
| b_ = 0.14 | |
| a_ = 0.02 | |
| elif curve == 'IEC Very Inverse': | |
| b_ = 13.5 | |
| a_ = 1 | |
| elif curve == 'IEC Extremely Inverse': | |
| b_ = 80 | |
| a_ = 2.0 | |
| elif curve == 'IEC Long Time Inverse': | |
| b_ = 120 | |
| a_ = 1.0 | |
| else: | |
| st.error("Invalid Curve Selected.") | |
| return | |
| # Calculate fault trip time | |
| try: | |
| fault_time = b_ * tms / (((i_f * (ct_sec / ct_pr) / (pick * ct_sec)) ** a_) - 1) | |
| except ZeroDivisionError: | |
| st.error("Error: Division by zero in fault trip time calculation. Check input values.") | |
| return | |
| # Generate data for the relay curve (current vs time) | |
| x_curr = np.linspace(pick * ct_pr * 1.1, pick * ct_pr * 5, 500) | |
| y_time = [] | |
| for x in x_curr: | |
| try: | |
| time = b_ * tms / (((x * (ct_sec / ct_pr) / (pick * ct_sec)) ** a_) - 1) | |
| y_time.append(time if time > 0 else np.nan) # Avoid negative/undefined times | |
| except ZeroDivisionError: | |
| y_time.append(np.nan) | |
| # Display results | |
| st.write('### Results:') | |
| st.write(f'**Rated Current:** {tr_curr} A') | |
| st.write(f'**Pickup:** {pick} x In') | |
| st.write(f'**Fault Current:** {i_f} A') | |
| st.write(f'**Trip Time:** {round(fault_time, 3)} sec') | |
| # Plot the relay curve | |
| fig, ax = plt.subplots(figsize=(10, 6)) | |
| ax.plot(x_curr, y_time, label="Relay Curve", color='blue') | |
| # Mark the fault current and trip time on the graph | |
| ax.axvline(x=i_f, color='red', linestyle='--', label=f"Fault Current: {i_f} A") | |
| ax.axhline(y=fault_time, color='green', linestyle='--', label=f"Trip Time: {round(fault_time, 3)} sec") | |
| # Adding labels and title | |
| ax.set_xlabel('Current (Amp)') | |
| ax.set_ylabel('Time (sec)') | |
| ax.set_title(f"Relay Curve: {curve}") | |
| # Adding a legend | |
| ax.legend() | |
| # Show the plot | |
| st.pyplot(fig) | |
| # Streamlit app layout | |
| st.title("Relay Curve Calculator") | |
| st.sidebar.header("Input Parameters") | |
| # Input fields | |
| tr_kva = st.sidebar.number_input("Transformer Rating (kVA)", min_value=1.0, value=1000.0, step=1.0) | |
| tr_volt = st.sidebar.number_input("Transformer Voltage (V)", min_value=1.0, value=11000.0, step=1.0) | |
| ct_pr = st.sidebar.number_input("CT Primary (Amp)", min_value=1.0, value=200.0, step=1.0) | |
| ct_sec = st.sidebar.number_input("CT Secondary (Amp)", min_value=1.0, value=5.0, step=1.0) | |
| fac = st.sidebar.number_input("Fault Anticipation Factor", min_value=1.0, value=1.2, step=0.1) | |
| tms = st.sidebar.number_input("Time Multiplier Setting (TMS)", min_value=0.01, value=0.1, step=0.01) | |
| i_f_fac = st.sidebar.number_input("Fault Current Multiplier", min_value=1.0, value=10.0, step=0.1) | |
| curve = st.sidebar.selectbox("Relay Curve Type", ['IEC Normal Inverse', 'IEC Very Inverse', 'IEC Extremely Inverse', 'IEC Long Time Inverse']) | |
| # Run the calculation when the button is clicked | |
| if st.sidebar.button("Calculate"): | |
| calculate_relay_curve(tr_kva, tr_volt, ct_pr, ct_sec, fac, tms, i_f_fac, curve) | |