Drive units

Motor Drive Unit MZ 4.4

The MZ 4.4-type Motor Drive Unit is the most used one. It is designed for all kinds of tap changers produced by Elprom Heavy Industries. It can be used for tap changers made by other manufacturers too, as well as a replacement for outdated motor drives. The MDU enclosure is made of aluminium alloy. The front panel is protected from environmental influences by a protective cover (door). The motor drive unit is equipped with a lighting unit, a power outlet, a document pocket etc. by default. Additional functions can be added to the MDU according to customer's requirements expressed in the order sheets.


Technical data

  • Electrical motor rated power 0,75 / 1,1 kW (0,9/1,3 for 60 Hz)
  • Rated frequency 50 / 60 Hz
  • Supply voltage 3 AC 380/400 V
  • Synchronous speed 1500 min -1 (1800 for 60 Hz)
  • Revolutions of hand crank per tap change operation 33 revs
  • Revolutions of outgoing shaft per tap change operation 33 revs
  • Drive shaft torque 17 / 24 Nm
  • Duration of the tap change operation 4,5 s
  • Maximum number of operating positions 35
  • Control circuit voltage AC 220/230 V
  • Insulation level of voltage Ph - PE 2,5 kV
  • Heater elements power 300 W
  • Protective degree IP55
  • Weight 104 kg


The special executions of motor drive are offered, answering to the specific requirements of client as:


  • Degree of protection IP 66.
  • Revolutions of outgoing shaft per tap change operation: 0,5; 1,6; 16,5.
  • Various supply voltage for operation and control circuits by requiring of client.
  • Execution for a cold climate with power of heating elements 4х150 W for working temperatures to - 60°С.
  • With single phase el. motor
  • Drive shaft torque 50 Nm
  • Box from stainless steеl
  • Maximum number of operating positions - 125