If I had to guess, I would figure that there is a typo on the name plate, and that it should say 240/480. The nameplate voltages on motors are usually lower than the nominal supply voltages, eg. 230/460 for a 240/480 supply, so this is still a little odd.
Guessing further, the motor uses standard NEMA numbering, that the delta connection is what is normally used for running at nominal voltage, and the wye connection is used for starting. See
http://www.malloyelectric.com/pages/tech/connections.html
Having said this, I would want to double check with measurements. You can easily check continuity to see if that matches the NEMA standard, but this won't tell you polarity of the coils. There are specialized analysis tools that can be used to measure polarity, but if this is not something that you are going to do frequently I doubt that it is worth the investment. Instead I would connect the motor in my best guess as to the proper connection, and then power it at reduced voltage and measure currents on the various leads.
-Jon