PLACEHOLDER fix for 161/500 kV transformer

Author: danielolsen

prereise/gather/griddata/hifld/const.py

@@ -144,7 +144,7 @@
     (138, 765): 0.02284,
     (161, 230): 0.06539,
     (161, 345): 0.03293,
-    (161, 500): 0.06978,
+    (161, 500): 0.015,
     (230, 345): 0.02085,
     (230, 500): 0.01846,
     (230, 765): 0.01616,