What is rated torque of DC motor?
The rated torque is the maximum continuous torque that the motor produces at rated RPM when working normally and without overheating, whereas the stall torque is produced by the motor when RPM is 0 while the load is attached or at starting. DC Motors manufacturers usually provide the stall torque rating.
What is the maximum efficiency of dc motor?
The motors are normally designed to have maximum efficiency while working at or near full load. The efficiency of a dc motor at normal operating conditions may be as high as 95%.
How is the torque speed of a DC motor calculated?
Normally, torque-speed curves are generated by plotting motor speed, motor current, mechanical output power, and efficiency as functions of the motor torque. The following discussion will describe the construction of a set of torque-speed curves for a typical DC motor from a series of raw data measurements.
When does maximum efficiency occur in DC motor?
Maximum efficiency occurs at about 10% of the motor stall torque. The denominator is known as the resistive power loss. With some algebraic manipulation, the equation can be simplified to: Please keep in mind that km (motor constant), shouldn’t be confused with kM (torque constant).
How does a motor react to a fixed torque value?
Then imagine that a motor is reacting a fixed torque value, and the supply voltage is increased to raise the output speed. A fixed torque and a rising speed means a rising output power. However input power is fixed, since torque is fixed because current is fixed.
What is the current rating of a DC motor?
Thus current ratings are often given when the motor is stalled. At this point it is drawing the maximum amount of current and applying maximum torque. A low voltage (e.g., 12 Volt or less) DC motor may draw from 100 mA to several amperes at stall, depending on its design.