Abstract: A method and apparatus for detecting winding errors in electric motor stators having a plurality of field windings is disclosed. The method involves the steps of applying a current source to at least one of the field windings to generate a magnetic field within the stator, measuring the polarity and strength of the field for each winding at preselected radial and angular positions about a circumference of the stator bore, and comparing the measured values to recorded values of radially and angularly corresponding measurements for a reference motor stator. Preferably, the current source is applied to each of the windings in succession. The apparatus includes a terminal block, switch, and power supply to connect a source of current to each field winding in succession to generate a magnetic field within the stator.

Abstract: A method and apparatus provides two testing stations at a single conveyor location to permits one part, such as electric motor armatures, to be tested while another part is being loaded or unloaded from a single conveyor system. Two testing heads are mounted on a reciprocating mechanism which allows the testing heads to be moved parallel to and independently of the conveyor system so that one or the other part may be aligned with a single loading and unloading station on the line at any given time. A part is first loaded into test station #1 and is then moved away from the loading station as testing station #2 is moved to it. When an electrical test on the part previously loaded into testing station #2 is finished, testing immediately begins on the part just loaded into test station #1. The part in testing station #2 is unloaded into the space vacated by the previous part, the conveyor is indexed, and the next part is loaded into testing station #2.

Abstract: Friction torque of a motor undergoing testing is measured by supporting an electrical motor on a test fixture and connecting a torque measuring device to its output shaft. The motor shaft is rotated in the reverse direction and while the motor shaft is freely rotating, power is applied to the motor and two torque measurements are taken to determine friction torque. The first is while the motor is still rotating in the reverse direction, and the second is taken from zero rpm to approximately 50 rpm. In both cases, the torque is measured while the motor shaft is near zero rpm, thus representing locked rotor torque. Half the difference between these two torque measurements will yield the value for friction torque. Motor torque is continued to be measured while the motor is accelerated to its maximum speed, and the value of this measured torque can then be adjusted by the value of the friction torque to provide a measurement of the actual torque of the motor being tested.

Abstract: Friction torque of a motor undergoing testing is measured by supporting an electrical motor on a test fixture and connecting a torque measuring device to its output shaft. The motor shaft is rotated in the reverse direction and while the motor shaft is freely rotating, power is applied to the motor and two torque measurements are taken to determine friction torque. The first is while the motor is still rotating in the reverse direction, and the second is taken from zero rpm to approximately 50 rpm. In both cases, the torque is measured while the motor shaft is near zero rpm, thus representing locked rotor torque. Half the difference between these two torque measurements will yield the value for friction torque. Motor torque is continued to be measured while the motor is accelerated to its maximum speed, and the value of this measured torque can then be adjusted by the value of the friction torque to provide a measurement of the actual torque of the motor being tested.

Abstract: A testing apparatus for rotors of electric motors comprising a test fixture including a fixture shaft on which a rotor is temporarily attached to a known inertial load. A stator creates a rotating magnetic field to cause rotation of the rotor, and an encoder senses the amount of angular rotation of the rotor in short time intervals, which is recorded in a memory and later used to calculate torque. An index mark from the encoder indicates each complete revolution of the rotor and may be used to determine the location of a defective rotor segment by reference to a start point mark placed on the rotor prior to the test. An electronic control circuit initially applies a low value electric current to the stator to create a rotating magnetic field to cause the rotor to rotate at a slower than normal rate to improve the resolution of the torque measurement. After the rotor has accelerated to a predetermined value, the stator voltage may be increased.

Abstract: A method and apparatus for testing the starting torque of electric motors includes attaching a flywheel of known diameter and weight to the motor's shaft along with an incremental encoder and measuring the amount of shaft rotation during known time intervals. A counter receives the output pulses from the encoder and a data latch captures the value of the counter at regular time intervals, such as once or twice during a cycle of an alternating current power line or upon zero crossing of the current to the motor. The count for each interval is retained in computer memory and later compared with a previous count to indicate changes in RPM from one interval to another. The change in RPM is a function of torque and can be plotted against motor speed, which is also calculated from the encoder output.

Abstract: A transistorized circuit is used for controlling the flow of current through a high voltage source, such as a battery. The high voltage source must be capable of being tapped at voltages less than the critical voltage of the transistors in the circuit, that is, that voltage at the maximum current through the transistor, above which the breakdown characteristics or maximum power dissipation ability of the transistor is exceeded. A plurality of transistor arrays are connected in series with each other, and each array is connected to a tap on the voltage source. Each array includes parallel connected transistors in sufficient quantity to achieve the desired current flow. The current through each array is made equal by control circuits so that no current flows through the tapped connection to the voltage source. The transistorized circuit may be used to control both the charging and the discharging rate of current through a high voltage battery.