Don't start your motor with propeller at full pitch

[Mark R]

There's a slight possibility of overload.

Video

 

[Rubycon]

Nice Back To The Future reference there!

I've seen that video and the description (bow thruster) makes little sense.
Our bow thrusters (3) are approximately 3MW each and have a motor that runs a hydraulic "power pack" They start across the line and when are ready the actual propeller (inside a tunnel) can be controlled remotely from a console on the bridge. It's pretty neat how the system works. The propellers are fixed pitch, the speed is varied either by computer or by hand depending on the role. (docking maneuver vs. fixed position maintain function, etc.)

In any case the flashover is pretty severe in that video. Worth watching for that.
Sounds like a cycloconverter drive. That's going to be expensive to repair!

As for starting motors with too steep of a pitch on the screws they will turn as the starting torque is quite high. Perhaps something was amiss such as some rope or other FOD fouling the bearings increasing the load. In any case OCR protection should have tripped long before time of death.

 

[olds]

Jesus. What was the purpose of the first minute and 10 seconds of that video?

 

[Rubycon]

Jesus. What was the purpose of the first minute and 10 seconds of that video?

Hear mister bone stripper contactor pull in, hear mister bone stripper transformer whine like a plugged polyphase motor, see mister bonestripper transformer primaries go flash, bang! :biggrin:

Yeah, that's nothing but trouble. (and yes the Judge's nose is indeed a penis!)

 

[BladeVenom]

http://youtubetime.com/

 

[IronWing]

There's a slight possibility of overload.

Video

There just happened to be a camera pointed at the box or was this intentional?

 

[TurtleCrusher]

Class C fire baby!

 

[Rubycon]

Class C fire baby!

Air cooled transformers are safe, when power is killed flames extinguish quickly on their own. Now if OC protection fails on secondaries of a large oil filled transformer and the oil heats up until pressure blows (BLEVE) and flashed vapor ignites by arc you have one hellacious fire!