Resilience tweaks and tweak final circuit cable rating method

powerplan/cable_data.py

@@ -26,6 +26,7 @@
     (630, None, None, 861),
 ]
 
+# CSA, two-core DC, two-core AC, multi-core AC, touching AC, touching DC
 cable_data["4F1A"]["voltage_drop"] = [
     (4, 12, 12, 10, None, None),
     (6, 7.8, 7.8, 6.7, None, None),
@@ -46,6 +47,29 @@
     (630, None, None, None, 0.068, (0.079, 0.170, 0.185)),
 ]
 
+# Flexible cables, non-armoured
+cable_data["4F3A"] = {}
+# Note that there are derating factors based on temperature.
+cable_data["4F3A"]["ratings"] = [
+    (0.5, 3, 3, None),
+    (0.75, 6, 6, None),
+    (1, 10, 10, None),
+    (1.25, 13, None, None),
+    (1.5, 16, 16, None),
+    (2.5, 25, 20, None),
+    (4, 32, 25, None),
+]
+
+cable_data["4F3A"]["voltage_drop"] = [
+    (0.5, None, 93, 80, None, None),
+    (0.75, None, 62, 54, None, None),
+    (1, None, 46, 40, None, None),
+    (1.25, None, 37, None, None, None),
+    (1.5, None, 32, 27, None, None),
+    (2.5, None, 19, 16, None, None),
+    (4, None, 12, 10, None, None),
+]
+
 
 # Eland Cables H07RN-F Cable Datasheet
 cable_data["Eland"] = {}

powerplan/cables.py

@@ -21,7 +21,7 @@ def select_cable_size(current: int, methodology: str, configuration: CableConfig
     return None
 
 
-def get_cable_ratings(csa: float, methodology: str, configuration: CableConfiguration) -> Dict:
+def get_cable_ratings(csa: float, methodology: str, configuration: CableConfiguration) -> Optional[Dict]:
     data = cable_data[methodology]
 
     voltage_drop = None
@@ -41,6 +41,9 @@ def get_cable_ratings(csa: float, methodology: str, configuration: CableConfigur
         if csa == row[0]:
             voltage_drop = row[col]
 
+    if rating is None or voltage_drop is None:
+        return None
+
     return {"rating": rating, "voltage_drop": voltage_drop}
 
 

powerplan/diagram.py

@@ -34,9 +34,20 @@ def _render_port(current, phases, count=1):
     return txt
 
 
-def calculate_max_length(V, Z_s, I_n: float, csa: float):
+def calculate_max_length(
+    V,
+    Z_s,
+    I_n: float,
+    csa: float,
+    methodology: str = "Eland",
+    cable_config: CableConfiguration = CableConfiguration.TWO_CORE,
+):
     """Calculate maximum length of a cable which will still satisfy the fault current requirement."""
-    ratings = get_cable_ratings(csa, "Eland", CableConfiguration.TWO_CORE)
+    ratings = get_cable_ratings(csa, methodology, cable_config)
+    if ratings is None:
+        raise ValueError(
+            f"No ratings found for CSA: {csa}mm², methodology {methodology}, configuration {cable_config}"
+        )
     cable_r1 = (ratings["voltage_drop"] / 1000) * (ureg.ohm / ureg.meter)
     max_z_s = (V / (5.5 * I_n)).to(ureg.ohm)
 
@@ -85,18 +96,20 @@ def _node_additional(node: PowerNode) -> dict:
 
             circuit_length_params: list[Tuple[int, float]] = []
             for i_n in sorted(output_ratings, reverse=True):
-                csa = select_cable_size(i_n.magnitude, "Eland", CableConfiguration.TWO_CORE)
+                csa = select_cable_size(i_n.magnitude, "4F3A", CableConfiguration.TWO_CORE)
                 if csa is None:
                     continue
                 circuit_length_params.append((i_n, float(csa)))
 
-                if i_n <= 16 * ureg.A:
-                    # For circuits 16A and lower also include a worst-case 1.25 mm^2 CSA
-                    circuit_length_params.append((i_n, 1.5))
+                if i_n == 16 * ureg.A:
+                    # For 16A also include a worst-case 1.25 mm^2 CSA as these
+                    # cables are sometimes seen.
+                    circuit_length_params.append((i_n, 1.25))
 
             final_circuit_lengths = []
-            for (i_n, c_csa) in circuit_length_params:
-                max_length = calculate_max_length(node.voltage_ln, z_s, i_n, c_csa)
+            for i_n, c_csa in circuit_length_params:
+                # Calculate final circuit lengths using BS7671 table 4F3A (flexible, non-armoured)
+                max_length = calculate_max_length(node.voltage_ln, z_s, i_n, c_csa, methodology="4F3A")
                 final_circuit_lengths.append(
                     "{:.4~H} @ {:~H} ({:} mm<sup>2</sup>)".format(max_length, i_n, c_csa)
                 )

powerplan/test_schedules.py

@@ -32,7 +32,7 @@ def generate_schedule(plan: Plan):
 
             for c, c_data in b.outputs():
                 # Test each adjustable RCD
-                if c_data["rcd"] in ADJUSTABLE:
+                if "rcd" in c_data and c_data["rcd"] in ADJUSTABLE:
                     tests[grid.name][c.name] = {
                         "source": b,
                         "node": c,