tandem control

from The Collaborative International Dictionary of English v.0.48
Cascade system \Cascade system\ (Elec.)
   A system or method of connecting and operating two induction
   motors so that the primary circuit of one is connected to the
   secondary circuit of the other, the primary circuit of the
   latter being connected to the source of supply; also, a
   system of electric traction in which motors so connected are
   employed. The cascade system is also called

   {tandem system}, or {concatenated system}; the connection a

   {cascade connection}, {tandem connection}, or {concatenated
   connection}, or

   {a concatenation}; and the control of the motors so obtained
      a

   {tandem control}, or {concatenation control}.

   Note: In the cascade system of traction the cascade
         connection is used for starting and for low speeds up
         to half speed. For full speed the short-circuited motor
         is cut loose from the other motor and is either left
         idle or (commonly) connected direct to the line.
         [Webster 1913 Suppl.]