Martensyte
Mechanical
- Oct 29, 2005
- 9
I have an old wound rotor hoist motor that I would like to find the breakdown and locked rotor torque for... or at least narrow it down a bit.
It is a "Lancashire Dynamo and Crypto" vintage ~1932, 60 hp, 220V, 900 rpm, 30 min rating. (I've often wondered what the heck a 'crypto' is)
I have two references that give generic info on these old motors, but nothing very specific. Currently I'm taking the max to be 275%, but I'd like some assurance that it is not significantly higher than that. NEMA MG1 says 375% should be used for design of "mechanical equipment" with wound rotor motors, but our concern is the hoist structure, and the 375% criteria seems too conservative for design of the structure.
It is a "Lancashire Dynamo and Crypto" vintage ~1932, 60 hp, 220V, 900 rpm, 30 min rating. (I've often wondered what the heck a 'crypto' is)
I have two references that give generic info on these old motors, but nothing very specific. Currently I'm taking the max to be 275%, but I'd like some assurance that it is not significantly higher than that. NEMA MG1 says 375% should be used for design of "mechanical equipment" with wound rotor motors, but our concern is the hoist structure, and the 375% criteria seems too conservative for design of the structure.