How do you know if a rotor bar is broken?

How do you know if a rotor bar is broken?

VIBRATION SPECTRUM ANALYSIS – This test can detect cracked or loose bars while under load. Under load, the vibration will modulate at a rate equal to the number of poles times slip frequency. With a broken rotor bar, the amplitude of the beat increases with load.

What causes broken rotor bars?

When centrifugal forces are combined with thermal expansion, the bars will likely bend at the rotor slot and result in another cyclic force that can result, over time, in a broken rotor bar.

What is broken rotor bar?

Broken rotor bar is one of the commonly encountered induction motor faults that may cause serious motor damage to the motor if not detected timely. Past efforts on broken rotor bar diagnosis have been focused on current signature analysis using spectral analysis and wavelet transform.

How do you test a rotor?

The AC impedance test is used to find indications of shorted rotor turns. The test is performed by means of applying an AC voltage across the field winding and raising it in 10-volt steps up to 100-120 volts, or till the current supply gets maxed out.

How many rotor bars does my motor have?

One other method to determine the number of rotor bars it to examine the the RBPF +/- K*2LF pattern in vibration: take vibration using high Fmax (above RBPF) and high # lines (to get good frequency resolution) – something like Fmax=300,000, lines =6400. Look for the set of peaks separated by by 2*LF.

What happens if your rotor breaks?

Even the slightest defect on the rotor will cause low-frequency vibrations, known as “judder,” during braking. If you notice this, you should see your mechanic right away. Serious rotor failures can cause a complete wheel lock-up and the driver will lose control of the vehicle.

What causes 2X line frequency?

The magnetic flux produced by current-carrying conductors in AC machines alternates at line frequency (FL). Therefore all AC motors produce a 2 X line frequency vibration. In power systems that operate at 60 Hz, the vibration frequency is 120 Hz.

How do you test a brake rotor assembly?

You may test the rotor once you’ve taken apart the alternator.

1. Remove and disassemble the alternator as indicated in your vehicle’s maintenance manual.
2. Visually inspect rotor shaft, slip rings and windings.
3. Connect one probe of the ohmmeter to a slip ring and the other to the shaft.

How do you check a rotor with a multimeter?

Select the Ohms scale & place one of each testing probe onto each slip ring & check the ohms reading which should be low (e.g. 2–4 ohms) & you can check between the slip rings & the rotor frame which should measure infinity ohms ! Set multi-meter to measure DC Volts in 20V range.