Is that possible?
It is about 330 kW,380 V; 50 Hz; Delta-connected; 2 pole motor with 48 slots and 2 circuits.
The winder wanted to avoid the 18 wires in hand and he tried to make 4 parallel circuits with 9 wires instead of 2 circuits with 18 wires, despite the fact that it's about 2 pole winding. He did it in this way ( only one pole-phase group of 8 coils is shown):
Is it a good solution?
There are two main conditions that should be met for all parallel circuits:
1.- MMF's of both parallels must be "co-phase" ie. angle between them must be 0 or close to 0;
2.- MMF's amlitude must be the same or close to same,
The both conditions can be checked using our ACW Analysis software.
Here is the result of analysis for two circuits shown above:
As you can see the first condition is not met.
This angle will cause the "new voltage source" inside the loop of two parallels:
and, consequently, the circulating current, that could be significant, depending on active and reactive impedance of single path:
This circulating current will overheat the one of two paths.
Obviously, this option is bad solution.
Is there any better option?
Shane from US suggested following arrangement:
- Path A: 1,2,7,8
- Path B: 3,4,5,6
A brief analysis is shown below:
As you can see, this time the second condition is not met and consequences are very similar.
This option is bad solution, also.
How to get the correct solutions?
Update:
Alecsei (Russia) is claiming that two parallel circuits can not be created inside the one pole-phase group. But, he is wrong. We are able to create: - 2 circuits inside the same pole-phase group ( means: 4 circuits per phase) with neglected angle among them, as you can see below:
- or 4 circuits using the coils of both pole-phase groups , as you can see below:
This last solution is the best one and it is available to purchase here . Ask for title: 2 POLE WINDING WITH 4 PARALLEL CIRCUITS
Notices: - Winding factor is depending on what the span is used ( can be changed with the same patern), - This arrangement is feasible for each winding with q = 8.
For any other number of slots and circuits , please, contact us.