Application and operation of D-C drives on rubber calenders

D-C motors are used almost universally on rubber calenders to obtain a wide speed range, good speed regulation, maximum braking under emergency conditions, suitable matching of speeds of the auxiliaries with the calender, and on the modern drives, electrical tension regulation of the fabric. The majority of the calenders in operation are driven by adjustable speed d-c motors with conventional armature resistor starting and with rheostat control of the motor field for speed regulation. The more modern installations are equipped with adjustable voltage systems to obtain greater flexibility of operation, better synchronization with auxiliary machines, more suitable power for the constant torque requirements of calender loads, and improved electrical braking under emergency conditions.