Contents
What happens when the temperature of a DC motor increases?
As the motor temperature increases, the resistance will increase and the torque constant and voltage constant will decrease. This results in an increase in no-load speed and a decrease in locked-rotor torque. Figure 2 illustrates an example of both “cold” and “hot” running conditions of the same DC motor.
How is the temperature of the AC motor measured?
As the winding temperature inside the motor can not be measured directly, measure the surface temperature of the motor case as a reference. For our AC motor, the temperature difference between the windings and the motor case is up to 30 ° C. The guidelines for each heat resistant class are summarized in the table below.
How does a thermal protector work on a motor?
A thermal protector is a feature that shuts off the input to the motor before it reaches the allowable winding temperature. It senses the winding temperature inside the motor and opens the contact point of the power line and stops the motor if it exceeds a certain temperature.
How can I stop the temperature rise on my AC motor?
As in condition A and condition B, setting the stop time equal to the operation time can suppress the temperature rise of the motor. As in the condition C to condition F, the shorter the stop time, the larger the temperature rise. The temperature rise can be suppressed by reviewing how to install the motor.
How is rotor damping calculated on a DC motor?
By no-load current — The block calculates rotor damping based on the values that you specify for the No-load current and DC supply voltage when measuring no-load current parameters. If you select this option, the Rotor damping parameter is not available for the Mechanical parameters.
What should the stall current be on a DC motor?
That makes 12.76 A a reasonable estimate for stall current. This is a reasonable approximation if the gearbox is ignored. Some portion of the 0.52A no-load current is due to the torque required to overcome friction, so the actual torque experienced by the stalled motor will be a little higher at stall than the calculated stall torque.
The torque-speed characteristic for the DC Motor block is related to the parameters in the preceding figure. When you set the Model parameterization parameter to By stall torque & no-load speed or By rated power, rated speed & no-load speed, the block solves for the equivalent circuit parameters as follows: