Reversing Star Delta Starter - Need Help

Reversing Star Delta Starter

Hello everyone,


I have acquired a used Milling Machine in need of a retrofit all wiring has been removed.
For this purpose I have a siemens Logo 0BA6 I intend to use with Hardware interlocking Contactors. The controls I would like are Start, Stop, Forward, Reverse, Low Speed, High Speed. Hardwired Safety isolator.

The 3 phase 0.85/1.1KW 1430/2850rpm two speed motor, has the markings U1,U2,V1,V2,W 1,W2.
I need some help with the interlocking logic, I can find many Ladder logic examples of basic start and stop with interlocks, But I don’t find any reversing a motor with dual speed, I think its by using U1,V1,W1 as one speed and U2,V2,W2 as the other.
Any help welcome.

CeeLtd said:

I don’t find any reversing a motor with dual speed, I think its by using U1,V1,W1 as one speed and U2,V2,W2 as the other.
Any help welcome.

Click to expand...

Here is a page with the connection diagram for a 6 lead IEC motor. The diagram is at the bottom of the page.

http://www.patchn.com/index.php?option=com_content&task=view&id=45&Itemid=34

The last time I did this I used a reversing contactor set feeding into another reversing contactor set and finally one more contactor. So you will need 5 contactors to pull this off.
In my opinion it's much more cost effective to just use a single VFD on one of the speeds. With the VFD you get the speed change and the reversing too.

CeeLtd said:

Reversing Star Delta Starter

The 3 phase 0.85/1.1KW 1430/2850rpm two speed motor, has the markings U1,U2,V1,V2,W 1,W2.

Motor with dual speed, I think its by using U1,V1,W1 as one speed and U2,V2,W2 as the other.
Any help welcome.

Click to expand...

The Motor described above is that of a 2 speed motor, and your choice of windings for the two speeds are correct.
I think the 1430 rpm is the U1 V1 W1.
the 2850 rpm is the U2 V2 W2.

A 2 speed motor only gets 3 wires powered at any stage, either Low speed or high speed, and you set it to the speed of choice and run it.

As a side note Star Delta Starting of this motor is not possible,as all 6 motor lead are powered to give a slower softer start in star, then the 6 wires get reconfigured as it nears or reaches full speed, to take it into delta the power working stage.
IF power is connected to all 6 wires then you let out alot of smoke.

Thanks for replying

Thanks for the info.

I am interested in the VFD option now, but I am wondering if I can use the existing motor or not.

It states on the Data plate THREE PHASE ASYNCHRONOUS MOTOR 400v Freq:50Hz.

If I used a VFD, which would be very handy to control when I convert to CNC.
Would the VFD have to limited to a 50HZ output?

CeeLtd said:

Would the VFD have to limited to a 50HZ output?

Click to expand...

If you wanted to error on the safe side then limit it to 50 hz.

Question: What is your incoming power? 400V 50hz, or 460V 60hz?

CeeLtd said:

I am wondering if I can use the existing motor or not

Click to expand...

This suggests that you are not "married" to this motor. If this is the case , then I would feel comfortable going faster than 50 hz, presuming your incoming power is 400v 50 hz. The reason for this is the "spikes" the inverter makes on the motor leads. The insulation needs to be able to resist them. Motor manufacturers are under price pressure, so 400V 50hz motors are made with less insulation than 460V 60hz motors.

I have a circa 1950's Gorton tracer mill that I bought for $160. This what they used before CNC milling. The tracer mechanism was broke but the rest worked for 3 years. Then the varispeed pulley system broke. I replaced it with a 5 hp @1750 motor and a sensorless vector drive, and did away with the vari pulley. I get good control from 3 hz to 120 hz. At speeds above 60 hz the motor has less torque, but at those speeds I do not need all the torque from the motor.

quote=milldrone

""
Question: What is your incoming power? 400V 50hz, or 460V 60hz?

incoming power is 400v 50 hz. The reason for this is the "spikes" the inverter makes on the motor leads. The insulation needs to be able to resist them. Motor manufacturers are under price pressure, so 400V 50hz motors are made with less insulation than 460V 60hz motors.

I have a circa 1950's Gorton tracer mill that I bought for $160. This what they used before CNC milling. The tracer mechanism was broke but the rest worked for 3 years. Then the varispeed pulley system broke. I replaced it with a 5 hp @1750 motor and a sensorless vector drive, and did away with the vari pulley. I get good control from 3 hz to 120 hz. At speeds above 60 hz the motor has less torque, but at those speeds I do not need all the torque from the motor.""

[FONT=&quot]I just did not find any VFD with less than 150HZ as their maximum. I have realised i already own a Lenze 1.5Kw VFD on another CNC I could transfer to this machine. I've found another motor in Germany which I like the look of for a future upgrade, it’s 400v 175Hz 3KW 9000rpm with an ISO30 Spindle and drawbar through the motor, it just looks like a normal big 3phase motor. My mill by the way is very similar to your IH Mill you have in the states. I’d like to do away with the gear driven head in the long run.[/FONT]

Star/Delta, 2 Speed, 2 Speed Pole Changing: Each of these describe different motor connections and need different methods to start and run them. First off you need to be certain which motor you have, then you can decide on the control method. Star/Delta is not a two speed control system, it is intended to reduce inrush current at start-up. 2 Speed may use two separate independent systems using U1,V1,W1 for one speed and U2,V2,W2 for the other though I tend to see more 2 speed Pole Changing. 2 Speed Pole Changing puts the supply onto U1,V1,W1 in slow speed and the supply onto U2,V2,W2 whilst shorting out U1,V1,W1 in high speed. I will see if I can dig up some control wiring schemes.

Bryan

Post a photo of the motor name plate.

I knew I had this diagram in an old catalogue but I managed to find it online. This is for a two speed, pole changing and reversing system. Lots of other good info here is you spend the time looking, make sure you use the <> buttons at the bottom of each page to get to more screens.

Bryan

CeeLtd said:

Thanks for the info.

I am interested in the VFD option now, but I am wondering if I can use the existing motor or not.

It states on the Data plate THREE PHASE ASYNCHRONOUS MOTOR 400v Freq:50Hz.

If I used a VFD, which would be very handy to control when I convert to CNC. Would the VFD have to limited to a 50HZ output?

Click to expand...

EXISTING motor the main problem with this will be the insulation will more than likely not be "inverter rated" thus will eventually break down. This will require rewind. You may not be able to get an inverter rated motor for this machine and may have to go with existing motor. I suppose for best reliability have the motor rewound now for inverter rating.



VFD If all controls are removed now is the time to get VFD.
I think I would connect to the high speed winding only.

YOu should be able to set the VFD volt output to 400. Read manual before purchase.
Frequency you can run the motor at above 50 Hz on a VFD. Torque will diminish but at higher RPM you wont be hogging so torque may not be an issue. If you wish the VFD can be set to a max freq of 50.

I believe at some point you will not use the gearbox (if so equipped) to select speeds - may be OK
BUT watch out at low motor speed say 30% or less and with hogging - the fan inside runs slower and will not provide adequate cooling. You should have little trouble if you run at half speed (the equivalent of the low speed winding) or at full speed (equivalent of hi speed winding). If mine I would use auxiliary fan to make double sure of adequate cooling especially so if you use motor as is.


Dan Bentler

I would suggest a sensorless vector VFD sized to run the motor connected in its low speed configuration. That will give you the maximum available torque at the lowest speeds.

To regain the higher speeds, program the drive to run the motor above 50hz up to the point where you have the higher speed back.

As to protecting the old motor insulation, install a 5% motor lead reactor between the drive and the motor. This will go a long way toward protecting your old motor and save the cost of a new or rewound one.

Be sure to set the drive up in sensorless vector mode. If you don't know how to do this, find a tech that does. Without that, the torque and speed regulation from the motor will be rather poor especially at low speeds. Also, as already stated, watch out for motor overheating at slow speeds. With milling machines, this is not often a problem because the heavy loads are usually intermittent allowing the motor to cool between cuts.

One last thing: I am assuming that the motor kw at the slow speed is not less than half of the high speed kw. If it is less than half, then use the high speed motor connection and size the drive to that.