Contactors in a WTG stator circuit 2

[sukantbh]

Hi All,
I have questions related to advantage/ disadvantage of using AC contactor for delivery of stator current in a WTG instead of LV circuit breaker. Please see image attached

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Three pole contactors are used in one phase to increase the current ratings.
Is there any standard which has mandated for electrical isolations through breakers and fuses and not through contactors. Is current split allowed for a circuit like WTG ?
Br
Sukant

 

[Gr8blu]

Contactors and breakers are not the same thing. The best reason for contactors in this application is the number of cycles the device will see in its lifetime. Not uncommon to see a switching action (open-to-close or vice versa) several times an hour.

Rotor currents in large wind turbine generators can be fairly high - upwards of 1000 A, for modern 3+ MW units. Hence the need for multiple parallel contactors to carry the required phase current. There is also - for some manufacturers - a benefit in being able to feed a portion of the rotor winding with a dedicated contactor. Hence in the image above, the rotor winding might actually be three parallel circuits.

Converting energy to motion for more than half a century

 

[che12345]

"...I have questions related to advantage/ disadvantage of using AC contactor for delivery of stator current in a WTG instead of LV circuit breaker...Three pole contactors are used in one phase to increase the current ratings...".
I have the following opinion for you consideration.
1. some contactors on the market rated 1kV up to AC-1 1650A. Max switching frequency AC-1 60 cycle/h. Attention: I[sub]cw[/sub] 12kA 1s. Therefore, should be coordinated with fuse as SCPD.
1.1 Attention: Contactor with fuse may cause "single-phasing"
2 Three pole contactors are used in one phase to increase the current ratings is NOT acceptable. It is fine if the additional poles are for longer durability, but NOT for increasing the single-pole current rating.
3. In general, CB is a better choice, but at a higher cost.
Che Kuan Yau (Singapore)

 

[sukantbh]

Dear Gr8blu,
Thanks for your reply, actually the Stator circuit has contactor and rotor circuit has a breaker and rating of stator contactor is 1400 A and it was meant to carry 1400x3 = 4200 A per phase in stator circuit.
Dear che12345,
Thanks for your reply , there are no fuses provided , it expected open SC current from the MV circuit breaker. The contactors are vacuum type.
Regards
Sukant