Okuma Howa Lathe

[JaxELectric]

Hey guys, quick question-

Customer called, bought a used O&H Act-4 lathe. The transformer is with the unit an operates @200v. The nameplate says 40kva. Right now it has been dropped off in a temporary storage facility where they would like to test it before pulling down their in use machine that it is replacing. This storage has an empty 100amp panel (3ø 230v). With the 140% I have the oc calculated over 100a . This thing will never see that much amperage I'd bet. I guess my concern is testing it there not knowing the coordination downstream. The storage is in an undustrial mill, same site as the Tooling company, different building though. Any thoughts or help with if we should fire this thing up there? They wont be milling anything, mostly a function check. Thanks!

 

[JaxELectric]

***the xfrmr is rated at 60kva, but the machine is rated at 40kva

 

[Fulthrotl]

***the xfrmr is rated at 60kva, but the machine is rated at 40kva

40k at 208 comes out to 111.03

that's taking a quarter inch cut, roughing in something.

all they want is a test drive, yes? hook it up with a piece of #2-4 SO cord,
and toss them the keys. the worst thing they could do is trip the breaker,
which they won't, and that is just a power outage. the machine is designed
to be safe in a loss of power situation. it hasn't been leveled where it's sitting,
either, so the accuracy will be iffy.

i did a ton of hookups for machine shops in the early 90's, for a machine tool
broker. it never ceased to amaze me what the specs. called for, and what the
machine actually pulled in service. night and day.

look inside the cabinet. if there are class S fuses in there, do your customer a
favor and buy two sets for where they are needed. if there is ever a utility spike,
those fuses tend to disappear off shelves in the area in five minutes. they are
expensive, but not like having a machine sit idle while you run around with your
hair on fire trying to find fuses.

 

[gar]

151211-1947 EST

JaxELectric:

There is an initial very short large inrush current from the transformer, probably 1/2 cycle, and charging the DC supply capacitors. The DC supply powers the main spindle and the servos. There can be more than one DC supply.

When the machine disconnect is first closed there is extremely little load, possibly a 0.1 kVA transformer. Maybe almost nothing. When the power on PB is pressed a CRM relay is pulled in, the DC supplies are powered, but with little load, and some small induction motors may be started.

When the servos are turned on then there is some small static positioning load.

When the main spindle is turned on at low starting speed, 500 rpm, but no load the power input might run 10 % of full load when cutting. Unloaded spindle power input at maximum RPM may be a large percentage, 30 %, of full load power. Unloaded spindle load is friction and increases with RPM. The increase with speed is a result of the lubricant viscosity.

Coolant pump when on will be approximately its maximum power, but this is not large compared to the fully loaded spindle.

I doubt you would have any problems doing a basic non-cutting or light load test of the machine.

There are a lot of low load tests that need to be performed on a machine before you ever use it to cut metal. These are functionality, positioning accuracy, backlash, unusual noise, ball-bar, collet clamping force, coolant flow, tool changer operation, spindle run-in from low speed to maximum speed over possibly at least 1 hour if the spindle has been idle for a long time while monitoring spindle power input (a meter on the machine), and voltages of the various supplies.

The customer needs your help during this initial tryout, and after the machine is in its final position. You can learn a lot thru observation and studying the CNC manual. This could be a good stepping stone into similar jobs.

You must run an EGC to the machine from the main panel supplying the machine.

If they plan to use RS232 communication from any distance, then try to sell them on use of my RS232 isolation system.

.

 

[JaxELectric]

Thanks!

Thanks!

Great responses guys, I have done a few of the smaller machines they've had. Just not this size. I def plan on observing the machine once they do the swap out, but for now they are going to make sure they didnt dump anything during the move. The riggers damaged the term block already so they are antsy to make sure its basic functions operate. So helpful! We will be in touch soon. You guys are great- :thumbsup:

 

[JaxELectric]

Soeedbump

Soeedbump

So..good news is the xfmr meggd fine and works. Bad news is there is no 208v primary. 230+
Machine runs on 200v. Wheren the hell do we find one that will run this thing?