Dc drive modules are offered by auto controls. These dc drive modules consist of all essential electronic power and control circuits. These power and control circuits are required for assembling thyristor-controlled dc drives. The idea is to enable original machine/plant manufacturers to build their own dc drive panels by adding necessary switchgear and control-accessories. There are some of the constructional features of this dc drive modules which include: dc drive panels are economical without sacrificing quality and at the same time it provides maximum flexibility in adopting changes in the specifications of the panel. The module consists of two sections: the power section and the control section. The power section consists of thyristor modules on appropriate heatsinks with or without forced cooling arrangement, depending upon the motor rating; control section is for thyristor firing angle control to enable smooth speed variation. In the same section, there are field bridge, field failure relay interlock and provision for indication. Current limit circuit as well as current trip circuit are incorporated. Following are some electrical features of these dc drive modules which include: provision for isolated armature voltage feedback or for giving tachogenerator feedback is also there; reference output too is available for synchronizing with other drive or master and ratio control drives; module can be easily converted into a complete dc drive by installing it in a proper enclosure and adding a contactor, potentiometer, fuses, meters, pushbuttons, blower motor starter and single phasing preventer.
