# What is “x Us” in a contactor coil specification?

I have a data sheet that gives the coil pickup voltage as "0.85…1.1 x Us] and coil dropout voltage as "0.3…0.6 x Us".

I am assuming that Us refers to the nominal or specified coil voltage, but why is it "Us"?

Thanks

• U is commonly used as as symbol for voltage on German schematics ... what make is the contactor? – Brian Drummond May 29 '15 at 20:34
• @BrianDrummond Here is a Siemens contactor spec. It uses exactly that nomenclature. – Spehro Pefhany May 29 '15 at 20:39
• The data sheet I have is from Rockwell (Allen-Bradley). – frog_jr May 29 '15 at 20:58

Subscript S in $U_S$ symbol stands for German word die Spule which means the coil. So $U_S$ is the coil voltage.