Squirrel cage motor - damaged rotor of the squirrel cage motor

Question

Hello, I have a 1.5 kW squirrel-cage motor, when idling (without load) it consumes a maximum of 4 A and heats up quite a bit. The resistance and conn...

karolark · Answer

Bearing condition? rotor runout? Show the photo of the windings.

MARCIN.SLASK · Answer

Is the current on each phase the same? In the event of a cage break, the rotor will heat up.

pakito1206 · Answer

The bearings are new, there is no rotor runout, the caps are good, the current is the same in all phases. All that remains is to check the rotor for a break. Has anyone tried to check it? Visually, it looks as if the core has been slightly shifted and someone has hit it before.

Krzysztof Reszka · Answer

You can see that the bearings were gone, the rotor is already damaged. Stator packages probably in the same condition.

pakito1206 · Answer

How can I check the rotor is it really damaged?

Krzysztof Reszka · Answer

In your case, visual observation is sufficient. Here is a photo of a good rotor, compare.

Berend · Answer

The rotor can be checked in several ways, including by removing the rotor and measuring whether the same current flows through each rod, or by measuring the amount of current flowing through the stator winding and then performing a fast Fourier transform in some program, this way is the best and non-invasive, but there are also many other ways.

Krzysztof Kamienski · Answer

You dont say ? Drill holes in the rotor and connect an ammeter? Personally, maybe twice in my life I have come across a damaged rotor in a three-phase asynchronous motor. However, when I suspect that the insulation of the "cage" is damaged, I examine it this way: I connect three stator windings in series and supply voltage of a dozen or so volts of alternating current through an ammeter, slowly turning the rotor by hand. current, I assume the rotor is electrically efficient.

Berend · Answer

Haven't heard about the induction method? An alternating current electromagnet with dimensions adjusted to the slot scale induces voltage in the individual bars of the rotor, if the bar has a connection with both rings, then a current flows in it, this current can be measured by a sensor (detector) which works on the principle of Dica bricks, where the magnetic circuit in this sensor is closed by the teeth adjacent to the tested bar and the rotor yoke.

grzeskk · Answer

The photos show that it is a fairly old motor from brothers from the east, 380V. Currently, there is 400V on the network, and maybe the author has more. Excessive heating may be due to higher voltage and saturated operation, not damage.