Update app.py

app.py

@@ -4,11 +4,12 @@ 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)
-    i_f = round(i_f_fac * tr_curr * fac, 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
 
-    # Curve coefficients
+    # Select curve coefficients based on relay type
     if curve == 'IEC Normal Inverse':
         b_ = 0.14
         a_ = 0.02
@@ -25,11 +26,11 @@ def calculate_relay_curve(tr_kva, tr_volt, ct_pr, ct_sec, fac, tms, i_f_fac, cur
         st.error("Invalid Curve Selected.")
         return
 
-    # Calculate trip time
+    # Calculate fault trip time
     try:
-        trip_t = b_ * tms / (((i_f * (ct_sec / ct_pr) / (pick * ct_sec)) ** a_) - 1)
+        fault_time = b_ * tms / (((i_f * (ct_sec / ct_pr) / (pick * ct_sec)) ** a_) - 1)
     except ZeroDivisionError:
-        st.error("Error in trip time calculation. Check input values.")
+        st.error("Error: Division by zero in fault trip time calculation. Check input values.")
         return
 
     # Generate data for the relay curve
@@ -38,28 +39,22 @@ def calculate_relay_curve(tr_kva, tr_volt, ct_pr, ct_sec, fac, tms, i_f_fac, cur
     for x in x_curr:
         try:
             time = b_ * tms / (((x * (ct_sec / ct_pr) / (pick * ct_sec)) ** a_) - 1)
-            y_time.append(time)
+            y_time.append(time if time > 0 else np.nan)  # Avoid negative/undefined times
         except ZeroDivisionError:
             y_time.append(np.nan)
 
-    # Fault time calculation
-    try:
-        fault_time = b_ * tms / (((i_f * (ct_sec / ct_pr) / (pick * ct_sec)) ** a_) - 1)
-    except ZeroDivisionError:
-        fault_time = np.nan
-
     # Display results
     st.write('### Results:')
-    st.write('**Rated Current:**', tr_curr, 'A')
-    st.write('**Pickup:**', pick, 'x In')
-    st.write('**Fault Current:**', round(i_f, 3), 'A')
-    st.write('**Trip Time:**', round(fault_time, 3), 'sec')
+    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()
-    ax.plot(x_curr, y_time, label="Relay Curve")
-    ax.axvline(x=i_f, color='red', linestyle='--', label="Fault Current")
-    ax.axhline(y=fault_time, color='blue', linestyle='--', label="Trip Time")
+    ax.plot(x_curr, y_time, label="Relay Curve", color='blue')
+    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")
     ax.set_xlabel('Current (Amp)')
     ax.set_ylabel('Time (sec)')
     ax.set_title(f"Relay Curve: {curve}")