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Rotary Converter hook up Run mode or Start mode ?

skipjackbill

Plastic
Joined
Mar 20, 2019
My lathe 5 hp 3 phase motor is currently wired in 220 run mode but also shows it can be wired for start mode . Trying to understand the difference and which way should I have it wired. Using a 10 hp rotary converter Thanks Bill
 
I agree with dalmatiangirl.

However, the wiring to the lathe should not be any different for connection to a rotary converter than if it was being connected to 3 phase from the power company.
 
Interesting, very interesting, never seen that before. Appears the start is Y on both voltages, and running is delta, not sure how that is supposed to work. Anyone else seen this before?

Have you opened motor junction box, are there actually 12 leads there?
 
Yes there is 12 leads and I changed it from the running configuration to the start but did not solve my problem of a direct short
 
Can you test each pair of wires, actually both ends of the same wire? Continuity and are they in contact with any other wires or the motor case?
Be sure all wire ends are disconnected.
 
I have only seen the Y start delta run used on much much larger motors. It provides a soft start at reduced voltage and greatly reduces the inrush current.

A control panel is needed with at least three contactors to start and switch between the two modes. There should be a mechanical interlock to prevent the simultaneous actuation of the two modes. A timer can be used to switch between the two modes. This is a lot of expense for a small motor.

You could probably just use the run mode. But one needs to ask why it has a start mode. If it was just to lessen start current on an anemic electrical supply there is no problem in just using run mode. If it was done for some other reason such as reducing stress on drive components at start up or electrical limitations of the motor then the risk is up to you.
 
Yes there are 12 leads and what I now know for my lathe motor to work off of my rotary converter is that it needs to be wired in the run mode.
 
I have only seen the Y start delta run used on much much larger motors. It provides a soft start at reduced voltage and greatly reduces the inrush current.

A control panel is needed with at least three contactors to start and switch between the two modes. There should be a mechanical interlock to prevent the simultaneous actuation of the two modes. A timer can be used to switch between the two modes. This is a lot of expense for a small motor.

You could probably just use the run mode. But one needs to ask why it has a start mode. If it was just to lessen start current on an anemic electrical supply there is no problem in just using run mode. If it was done for some other reason such as reducing stress on drive components at start up or electrical limitations of the motor then the risk is up to you.

Good information there !!! Thank you
 
The controller referred to is called a Star/Delta starter and is very common over here in the UK. As said it reduces start currents but is also beneficial to starting torque.

The system Starts the motor in Star configuration and the contactors are electrically and mechanically interlocked to prevent both connection types from being energised at once.

When the start signal is initiated as well as the Star contactor being pulled in a timer is also set running, the time at which this is set depends upon the characteristics of the drive system being driven, it is set so that the system has enough time to achieve full speed and consequently the start current will have now dropped off, at this point the timer drops out the Star connected contactor and pulls in the Delta connected contactor and the motor will be heard to accelerate a small amount again but the big difference is that because the drive system is already running then the initial Delta connected current will be much reduced compared to if it had been started from rest in Delta.

Hope this helps someone
 
The controller referred to is called a Star/Delta starter and is very common over here in the UK. As said it reduces start currents but is also beneficial to starting torque.

The system Starts the motor in Star configuration and the contactors are electrically and mechanically interlocked to prevent both connection types from being energised at once.

When the start signal is initiated as well as the Star contactor being pulled in a timer is also set running, the time at which this is set depends upon the characteristics of the drive system being driven, it is set so that the system has enough time to achieve full speed and consequently the start current will have now dropped off, at this point the timer drops out the Star connected contactor and pulls in the Delta connected contactor and the motor will be heard to accelerate a small amount again but the big difference is that because the drive system is already running then the initial Delta connected current will be much reduced compared to if it had been started from rest in Delta.

Hope this helps someone

Just for the record, there is also open and closed transition. Open transition totally disconnects the motor during the switchover time. The motor field looses sych with the line, resulting in spike of current as the motor resets to the line phase. Closed transition uses a resistor per phase to maintain the phase relationship.

Tom
 
My lathe 5 hp 3 phase motor is currently wired in 220 run mode but also shows it can be wired for start mode . Trying to understand the difference and which way should I have it wired. Using a 10 hp rotary converter Thanks Bill

Common enough. "Wye" start, "Delta" run, but as Bill S. pointed out, unless you have the OEM switch or (pseudo) "soft start" contactor still there to go with it, or it never HAD such, best to just wire it run-mode (Delta).

A mere 5 HP "solo" is generally too trivial to mess with if you have to source or DIY the change-over switchgear.

Now .. if that motor were to be applied as one of several in a given application, (think already-loaded conveyor belt line or such..) it mought have been very well worth it.
 
Just for the record, there is also open and closed transition. Open transition totally disconnects the motor during the switchover time. The motor field looses sych with the line, resulting in spike of current as the motor resets to the line phase. Closed transition uses a resistor per phase to maintain the phase relationship.

Tom

This is something I have never encountered, all the systems I have been near (I used to be a maintenance electrician in the local hospitals)going from your info Tom were of the open transition type.

I shudder to think what the circuit diagram for the closed transition type looks like!!
 
Probably not important to this discussion, merely adding it as another instance of the same sort of start/run windings.

I have a TECO 10HP motor I was thinking of using in my RPC and when I pulled the cover and found the same 12 wires, I remembered this thread. Mine has the same 12 wire dual voltage/dual mode data plate under the cover. I'm going to try to get my 5HP idler tuned, if not I will be using this 10HP motor.

If anyone needs a pic of the data plate, or any other info about this motor, just let me know.

Cheers
 
Now .. if that motor were to be applied as one of several in a given application, (think already-loaded conveyor belt line or such..) it mought have been very well worth it.

Since the motor is on a lathe, it is unlikely that a lot of lathes were started and stopped simultaneously, but it might be useful on something like an air compressor or a punch press with a very large flywheel. The soft start would be more for the benefit of the motor than the power co.

Bill
 








 
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