# Number of windings clarification

#### electronicsman

##### Full Member level 5
This is the image i saw, referring to the explanation of the 3Phase Synchronous motors. The doc says it is an empty stator containing just 3 coils, each 120 Degrees apart around the surface of the machine. But I see 6, like abc,a'b'c'. What are these a'b'c' coils? When it is referred to 3 coils does it always mean always 6 terminals. It can be different in different docs? Please advise.

#### KlausST

##### Super Moderator
Staff member
Hi,

3 coils always have 6 wires.

For a motor you may connect them
* in star = 3 + 1 wires
* in delta = 3 wires

Klaus

#### electronicsman

##### Full Member level 5
Is my understanding correct as shown

The terminals a,b,c are the actual phase winding's. The a',b',c' are the neutral points are ground? Can you please confirm if my understanding is correct?

#### KlausST

##### Super Moderator
Staff member
Hi,

The connections are correct.

Please call a'b'c' --> "Neutral", you already marked it with "N". It may be connected to earth ground or not.
You say one side is "motor" the other "load". But a motor is a load. But there is no source of power.
So either your motor is a generator, ...or your liad is a source, like mains grid, generator, source...

For equal load the current in "N" should be zero and thus may be omitted.

Klaus

#### electronicsman

##### Full Member level 5
Hi,

The connections are correct.

Please call a'b'c' --> "Neutral", you already marked it with "N". It may be connected to earth ground or not.
You say one side is "motor" the other "load". But a motor is a load. But there is no source of power.

So either your motor is a generator, ...or your liad is a source, like mains grid, generator, source...

For equal load the current in "N" should be zero and thus may be omitted.

Klaus
Yes i got confused. Yes my mistake motor is a load.

I need only one confirmation.
The a', b', c' i have seen in the document and posted in #1 are same as the a', b', c' i have shown in the diagram (which i have drawn on my understanding). Basically does both represent the Neutral?

#### FvM

##### Super Moderator
Staff member
The figure shows a simplified stator cross section, not the winding terminals. In so far it's arbitrary and misleading to use the winding labels as terminal designator. A real motor or generator has of course windings with many turns, the windings can be either connected in star or delta circuit. Neutral won't be connected for a three-phase motor.