Index: trunk/resources/data/validator/combinations.mapcss
===================================================================
--- trunk/resources/data/validator/combinations.mapcss	(revision 18527)
+++ trunk/resources/data/validator/combinations.mapcss	(revision 18535)
@@ -11,4 +11,7 @@
 
 /* {0.key} without {1.key} (warning level) */
+node[voltage:primary           ][!transformer],
+node[voltage:secondary         ][!transformer],
+node[voltage:tertiary          ][!transformer],
 way[junction                   ][!highway][junction!=yes][!area:highway],
 way[living_street              ][!highway],
@@ -346,5 +349,6 @@
 }
 
-/* {0.key} together with {1.key}, #18267, #17630, #17604 */
+/* {0.key} together with {1.key}, #18267, #17630, #17604, #21836 */
+node[transformer][voltage],
 node[marker][cover],
 node[marker][voltage],
@@ -1061,2 +1065,8 @@
   assertNoMatch: "relation piste:type=nordic piste:grooming=classic";
 }
+
+/* #21836 */
+*[voltage:primary][voltage:secondary][transformer=generator][tag("voltage:secondary")<tag("voltage:primary")] {
+  throwWarning: tr("{0} is lower than {1} on {2}.", "{1.key}", "{0.key}", "{2.tag}");
+  group: tr("suspicious tag combination");
+}