Abstract: A system and method for detecting a brake dragging during normal operation of a motor monitors torque at zero speed and at constant speed. For an inertial system acted upon by gravity, a value of torque required to maintain zero speed is approximately the same as a value of torque required to maintain operation at a constant speed. In an exemplary, elevator system, a motor drive determines the torque required to maintain zero speed operation of an elevator cab after a holding brake opens and before it begins controlling the motor to rotate. The motor drive again determines the torque required to maintain a constant speed and compares this value to the value of torque required to maintain zero speed. If the difference between the two values of torque is greater than a predefined threshold, then the motor drive determines that the brake is dragging and sets an error message.

Abstract: A system and method for detecting a brake dragging during normal operation of a motor monitors torque at zero speed and at constant speed. For an inertial system acted upon by gravity, a value of torque required to maintain zero speed is approximately the same as a value of torque required to maintain operation at a constant speed. In an exemplary, elevator system, a motor drive determines the torque required to maintain zero speed operation of an elevator cab after a holding brake opens and before it begins controlling the motor to rotate. The motor drive again determines the torque required to maintain a constant speed and compares this value to the value of torque required to maintain zero speed. If the difference between the two values of torque is greater than a predefined threshold, then the motor drive determines that the brake is dragging and sets an error message.

Abstract: An electronic system may include a mounting structure that allows a switch to be firmly attached to the electronic system. The switch may have one or more snap lock mechanisms attached to a body of the switch. The mounting structure may have an opening sized to allow the switch and the snap lock mechanisms to be inserted into the mounting structure. The mounting structure may include an undercut portion in a wall of the mounting structure. The mounting panel may also include a channel configured to accept a width of the snap lock mechanism. The undercut portion of the wall may be located in a channel wall. When the switch is inserted into the mounting structure, the snap lock mechanism may engage the undercut portion of the mounting structure to securely hold the switch to the mounting structure.