|Permanent magnet DC (PMDC) motors and gearmotors are compact, mathematically predictable, can produce high starting torque and can be decelerated rapidly.|
|Bodine PMDC motors and gearmotors have CE marks.|
|In a PMDC motor, speed is proportional to voltage and torque is proportional to current. When voltage is held constant, the amount that speed drops due to increasing torque is called “speed regulation”. The thin lines in Figure 1 illustrate motor performance without the aid of a regulating electronic control. The heavy lines illustrate performance from a control with “excellent” (1-3%) speed regulation.|
|Speed controls provide several functions: (a) converting input AC voltage to DC for the motor; (b) a potentiometer enables the user to select the motor operating speed; (c) “automatic” circuitry regulates the motor speed; (d) other functions, such as braking/reversing, temperature and line voltage compensation, can be provided at additional cost.
The design of the electronic speed control has a dramatic effect on motor speed performance and life. SCR speed controls can be: (a) 1/2 wave of full-wave; (b) filtered or unfiltered. Most industrial controls are full-wave. We will assume full-wave rectification and discuss difference between filtered and unfiltered.
|Form Factor (FF)|
|Form Factor for a DC voltage electronic control is a measure of the amount of current (ampere) filtering (smoothing) provided by the control to a motor. Form Factor cannot be determined until a motor and control combination are driving a load. However, most control manufacturers catalog their controls with a FF rating. Most small motor and control combinations exhibit FF=1.0 to 1.05 with a filtered control and FF=1.6 to 1.8 with an unfiltered control at rated torque.
Most Bodine permanent magnet DC motors are rated for continuous duty on 130 VDC, FF-1.05 current as supplied by Bodine type FPM and WPM controls. These motors and gearmotors can be successfully operated from unfiltered controls at FF=approximately 1.6, at speed not less than 1700 rpm. For intermittent duty operation, full nameplate torque may be available. The designers should test for each individual application.
|Peak torque indicates the maximum torques above rated that are acceptable when gearmotors are used with Bodine Controls. Peak torque is based on the load causing the motor portion to briefly exceed its rated horsepower and are limited by either 200% of rated torque or the approximate short term capacity of the gearhead. The user is cautioned that output torques higher than rated will reduce the life of the gearhead below its “design life”. Also, winding life will be reduced when rated load (rated temperature rise) is exceeded.|
|Motor Insulation Ratings|
|All Bodine PMDC motors are built with Class “F” insulation material (155°C total) for greater torque capability. However, the performance ratings of some models are based on Class “B” (130°C total) for extended life.|
|DC Connection Diagram – 074 10101|
|The performance curves below show motor performance on pure DC (FF=1.0)|