Hi all, I have recently been working on replacing a defective 690v 3 Phase induction motor driving a cooling fan,when i inspected the name plate it has a star configuration for slow speed and a star star configuraton for high speed.The motor has six terminal terminations (not including earth conductors). When looking at the wiring configuration to the fan its as follows; slow speed terminals 1,2 and 3 are used for 3 phase electrical supply. High speed consists of the supply for 1,2 and 3 being disconnected from the incomming supply and then all joined together via little jumper loops in a contactor,terminals 4,5 and 6 then supplies the motor.
Has anyone ever heard or worked with such a configuration?Does this configuration just double up the three phase field windings in star (like the name suggests), producing more electromagnetic force for the stator to react upon?
Where i work has the same wiring set up for other motors and pumps,any help on this matter would much appreciated!
Hi Trumpy, my situation is that im working on Danish wind turbines that are situated off the west coast of England which explains the Danish 690v.(Its prob so tney can use there own voltage rated components i.e motors,pumps etc.)
I spoke to a Danish engineer about this and he explained the best he could in English which is all the info in the first post,he told me off for saying it was star-delta config.
On the name plate it has a pic of a star config for slow speed and two star symbols next to each other for the high speed ratings.No Delta config in sight!
With the information 2 speeds, fan function and star - double star I suppose you got a motor with a reversible tapped winding what we call a "Dahlander motor" on the continent. Then the second sketch from the left on page 8-54 should fit.
In case the speed ratio is not equal 1:2, I missed it and need more input.
Furthermore 690V is root3 *400V. For star delta starters you mandatorily use a 690/400 motor, so this is sort of an absolute European standard, but usually in delta config. In an industrial context 690V 3ph isn't uncommon however. and it saves weight which might help on high poles, doesn't it.
Hotline 1, it will never happen again please forgive me for my actions!
Hi Wolfgang, your link provided me with the correct configuration and yes it was the second sketch from the left on page 54,even the the terminal numbers/letters tally up with what i have. I suppose my assumption that the phase windings are doubled up in star was correct,was just a little confused with this arrangement initialy. Thanks again Wolfgang for the excellant link and your input!