breaker sizing, 220V 1 Ph

[SR8CReliant]

I just got a lathe and a mill. The lathe uses 220 V 3 Ph, and the mill uses 480 3 Ph. All I have is 220 1 Ph coming into the building so I know I must buy inverters to make each machine run. However, the lathe motor has 7.6 FLA and the mill motor has 1.65 FLA. When the 220 1 Ph breaker panel goes in, how do you calculate the breaker size since it will be at 220V 1 Ph? I guess the minimum breaker size is 15A, but does the amperage change between 1 Ph and 3 Ph?

 

[itsmoked]

Certainly it changes since you now distribute the same load on two wires instead of three.

Have you investigated the mill to see if you can re-connect it at 230V instead of 460V? Almost all would provide for this. You are not likely going to find any 240V 1ph to 480V 3ph inverters so you want to look closely at reconnectability.

There are many ways to approach your solutions. Are both of these tools only motor driven or do they have other electrical aspects like controllers and such?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[SR8CReliant]

The mill already has an inverter, thank goodness. The lathe needs one (3 HP) now. There are little coolant pumps and DRO things to wire up, they are 110. No controllers, these are simple machines.

 

[melspuds]

SR8CReliant,
I think you have inverter and converter meanings confused. You state, that the mill has a inverter. To me that means a VSD (variable speed drive) and a converter changes single phase to three phase. The VSD most likely only works at 480 volts 3 phase. Check to see if the lathe motor can be changed to 480 volts. If it is a 2 speed motor, as most lathes are. you are suck with 230v. You might need 2 converters, one for 480v 3ph and 240v 3ph.
good luck,
Dave

 

[SR8CReliant]

My bad. I'm an ME, so need to be "schooled" on this EE stuff.
I have a converter for the mill, it has a round motor-like device with it. Not a VSD (VFD).
The lathe has a 2 speed wired for 220 (230? 210? 240?) at 1800 rpm. It does not use a VSD (VFD), it changes speed by gearbox sequencing, not belt drives. I would not want to change it to 480 if I could help it, since I don't know how.

 

[waross]

Reconnect the 460 Volt motor for 230 Volts. The diagram should be on the motor or inside the connection box. If the motor has ever been rewound it may have been changed from a 9 lead, 230/460 Volt motor to a 3 lead 460 Volt motor. If that is the case you may need either a transformer or a different motor.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[melspuds]

Your motor-like device is called a "roto-phaser". That is 230v single phase motor driving a 480v 3 phase little generator. Now check the nameplate on the roto-phaser for voltage 230v and amps also for 480v and amps (most likely it only 480v only). Then check both motor nameplates for hp, voltage and amps. Also check the motors to see if they can be changed to a different voltage as per Bills post. After you us the info requested, we can tell you the solution to your problem.
good luck,
Dave