MCA™ Deenergized Testing
How Does it Work?
The electrical portion of the 3 phase motor system is made up of the basic motor circuit, which is nothing more than 3 simple RCL circuits (resistive, capacitive, inductive). Each basic circuit represents one phase of the three-phase motor system. Since each phase of the motor system is identical, each basic circuit should respond the same way to an applied signal. This is also true for single-phase and DC motors.
ALL-TEST Pro instruments apply a series of low voltage, non-destructive sinusoidal AC signals through the motor windings and measure the response to these signals. Winding faults are indicated by variances in the response to the applied signal through the windings. This deenergized test takes only a few minutes and can even be performed by an entry-level technician.
The measurements* rendered by MCA™ include:
Resistance for connection and cable related issues.
Impedance and inductance for rotor issues, such as air gap, casting voids, and broken/fractured rotor bars.
Dissipation Factor to determine if the winding to ground is contaminated or overheated.
Developing winding shorts, turn to turn, coil to coil, or phase to phase are detected and trended using Fi (phase angle) & I/F (current frequency response) measurements.**
TVS™ (Test Value Static) is compared to a Reference TVS™ and if a change occurs this indicates that a change in the condition of the stator and/or rotor has occurred.
Dynamic Stator and Rotor Signatures™*** is used to automatically assess the condition of the stator and rotor, and provides the Stator & Rotor ‘OK’, ‘Warn’, or ‘Bad’.
It is important to note that TVS™ is independent of rotor position in a motor in good condition. TVS™ and the Dynamic Stator and Rotor Signatures™ are patent and patent-pending and represent a significant breakthrough in motor testing technology. Insulation to ground is also tested looking for issues related to the ground wall.
*Number of measurements depend upon model of MCA instrument.
**Fi is the phase angle of the applied voltage and the resulting flow of current measured in degrees. I/F is the percent reduction in current flow when the applied frequency is exactly doubled.
***Dynamic Stator and Rotor Signatures™ is for testing AC induction with squirrel-cage rotor motors <1000V.
The ALL-TEST Pro Promise
ALL-TEST Pro is committed to ensuring the reliability of motors in the field and maximizing the productivity of maintenance teams everywhere, backing every ALL-TEST Pro product with unmatched motor testing expertise. Our equipment is used in commercial, government and military institutions worldwide. Applications include AC/DC electric motors, transmission, distribution transformers, machine tool motors, servo motors,
AC/DC traction motors, and more.