2 Speed 1 Winding 3 Phase Motors 1

[Ahr35181]

We have some new workshop machines purchased from abroad, the wiring diagrams for the motor starters are identical to the following:-

http://www.ssusa.cc/reference/wiring_diagrams/standard_series_drawings/series_110/110_01.pdf

The are rated at 2.2KW / 1.1KW, but both overload relays are set at 4A (bottom of their range).

Could anyone provide links to info on these type of motors, i.e whether they are star or delta connected when in low & high speed?

Cheers,

Alan

 

[teco]

ahr35181

it looks like the motors you have are dahadler tap wound constant torque. the leads should be marked u1 v1 w1 u2 v2 w2.
for high speed supply w2-u2-v2 join together u1-v1-w1
for low speed supply u1-v1-w1 (others open)
trust this will help.
kind regds

 

[RRaghunath]

Teco,
I have a stupid question, if you care to answer.
The speed is decided by the no. of poles we say in any AC motor. Now, in two speed motors how are we able to change the speed by changing winding arrangement on the stator (when poles are on the rotor).

 

[SteveKW]

Typically, in a motor stator, the poles "groups" are wound right next to each other. In a two speed motor they are not and have several slots separating them from each other. Then the leads for each pole are brought out which allows for reversing of half the poles. Where normally the poles would be N,S,N,S, the South's are now reversed to make the poles "groups" N,N,N,N. And since every N has a S, the space between the wound poles now become the South's!
If you add them up now, where the motor used to be N,S,N,S, you now just doubled the poles to N,S,N,S,N,S,N,S.

Hope that helps.

 

[SteveKW]

Woops, missed your last part "(when poles are on the rotor)". I have not seen that type of motor. My answer dealt with a squirrel cage rotor which would mirror what the stator is doing.

 

[aolalde]

Hello Ahr35181:

Answering your original question:

The power ratio provided is 2.2kW/1.1kW = 2, which shows a constant torque winding.
For constant torque, single winding the connections are; One Circuit Delta in low speed and Two Circuits Wye for high speed. That connection is exactly made by the sprecher+schuh magnetic starter in the link.
The full load currents regularly are very close due to a low P.F. (power factor) for the low speed connection. Two speed motors are a compromise to optimize the performance at both speeds.

 

[RRaghunath]

Thanks SteveKW, I am educated.

 

[oldjeep]

If you were to supply w2-u2-v2 and leave u1-v1-w1 open, what would be the result? This may explain a problem that I have with the wiring in a 1940's Avey Drill press that I recently bought.

 

[SteveKW]

Typically, the motor will not run since the 2's are the "ends" of the 1's and you now have them open!

Here is a link, see the IEC section...

http://www.electricmotorwarehouse.com/motor_connection_diagrams.htm

 

[oldjeep]

Thank you for the link, that may explain my problem. At a minimum It appears that I have 4,5,6 connected to the wrong phases.

 

[oldjeep]

On my motor I have L1=4 L2=5 L3=6 powered 1,2,3 open and the motor will hum and move a little bit before kicking out the overload on my VFD. When Powering L1=1 L2=2 L3=3 with 4,5,6 open it works fine.

 

[akselj]

Very important when operating dahlander motors: Do never switch directly from high to low speed, the motor must have time to run down to lown speed, or lower before switching.
By direct switching, very high effect will be generatet and let into the mains, blowin the fuses.

In automatic starters you must install a timer to ensure this.

Greetings Aksel