______ brushes are fragile and cause excessive wear of commutator,

Related MCQs

• Which of the following brushes can be used for high values of current density ?
• ________ is the common method of applying brushes to the commntator.
• In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made
• ________ has a lowrelative permeability and is used principally in field frames when cost is of primary importance and extra weight is not objectionable.
• The insulation between windings and grounded core and the insulation between the windings of the same phase is called
• ______is extensively used for those portions of magnetic circuit which carry steady flux and need superior mechanical properties ?
• The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc.
• cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall
• In direct cooled system using hydrogen both stator and rotor conductors are made
• By which of the following methods the temperature rise of windings and other parts may be determined ?