A few photos and simple marks taken before removing a failed motor make sure the new motor is chosen correctly and fitted in the same, aligned position. If the arrangement of pulley, packing pieces and cables is lost during removal it is hard to remember afterwards, so the record is made before anything is taken apart.

DRG-802-4 0.75 kW 1500 rpm aluminium frame DRG three-phase motor – before removing a failed motor

What to photograph

  1. Nameplate: Square on, without glare, with every line readable. The serial number should be visible too.
  2. Overall view: The motor's position relative to the machine, shaft direction and which way the terminal box faces.
  3. Drive end: Pulley or coupling, number and type of belts, guard.
  4. Feet and base: Bolts, packing pieces or shims underneath, and the tensioning screw if there are slide rails.
  5. Flange mounting: Flange diameter, number of holes and spigot area.
  6. Terminal box: Connection layout and cable entry with the cover open. It is assumed that the supply has been isolated and removal is done by qualified staff.

What to mark

  • The position of the motor feet on the base: drawing round them with a paint marker makes it easier to bring the new motor roughly into line.
  • The position of the tensioning screw on a slide-rail base.
  • Cable ends: tags showing which lead goes to which terminal. Connection of the new motor, however, follows its nameplate and the judgement of qualified electrical staff.
  • The number of packing pieces and which foot each sits under.

Dimensions to measure

Note the shaft diameter and length, key width, shaft height (from the floor to the shaft centre), the transverse and longitudinal distances between foot holes, and the overall length of the motor. If the nameplate is unreadable, these dimensions are what identify the IEC frame.

Preserving evidence of the failure

If there is a burning smell, leaking grease, a broken part or water marks, photograph them before cleaning. These records help both to find the cause of the failure and to support a claim for a motor still under warranty.

You can identify the right frame by comparing the dimensions with the DRG technical drawings and review models of the same power and speed in the shop.