Rotor Contactors

dear everbody
can any body explain why in slip ring motor rotor short circuit contactors are connected in delta (not in star).
ram

Slip Losses

hello everybody
we have a cement mill driven by twin drive
These motor are identical slipring induction motors of 2100kw/11kv/rotor voltage 1455v and 1105 amps

There is a power difference of 100-150kw between the two motors.

The motors are started thru LRS and shorted by short ckt contactors.they are running at full speedonly always
The rotors cables are also of uniform size and equal length

can anyone comment on this
how to find the slip losses
ram

Scr Fuses

hello everybody

how about the positioning of thyristor fuses in dc drives for single quadrant applications
1) either in the line side( we will have only three)
2)before/after thyristors( in this case we will have 6 fuses)

which type is advantageous

ram

Overload Realy Setting

hello everybody

if we install capacitor across motor we have to make necessary adjusments in the overload relay

have we to adjust overlaod relay setting if we provide the same capcitor before overload relay and contactor(in the same starter -dol.ie after isolator) ram

Ac /dc Choke

hello everybody
what is the need for input and output chokes in variable speed drives
any criterial for choosing these
ram