The steel portion of the rotor and stator cores make up a series
of thin laminations (sheets) which are stacked and fastened together by cleats,
rivets or welds. Laminations are used
instead of a solid piece in order to reduce eddy-current losses.
Usually refers to AC motors with 5000 series frames and above
or DC motors with 500 series frames and larger.
The burden imposed on a motor by the driven machine. It is often stated as the torque required to
overcome the resistance of the machine it drives. Sometimes “load” is synonymous with “required power.”
Steady state current taken from the line with the rotor at
standstill (at rated voltage and frequency).
This is the current seen when starting the motor and load.
The minimum torque that a motor will develop at rest for all
angular positions of the rotor (with rated voltage applied at rated frequency).
A motor converts electrical energy into a mechanical energy
and in so doing, encounters losses. These
losses are all the energy that is put into a motor and not transformed to usable
power but are converted into heat causing the temperature of the windings and
other motor parts to rise.
In order to reduce wear and avoid overheating certain motor
components lubrication is required (application of an oil or grease). The bearings are the major motor component
requiring lubrication (as per manufacturer’s instructions). Excess lubrication can however damage the windings
and internal switches, etc.