Independent repair of the electric motor rotor

According to the device model of the electric motor are the same. The basis of the design - the rotor and stator. The rotor (unlike the stator) may not have a winding. Experts call a rotor with phase winding, and without it - short-circuited. The stator is a complex mechanical device that relates to asynchronous motors.

The scheme of the engine with an internal rotor.

Constituent elements

The cylindrical shaft is made of steel. Sheets of electrotechnical iron with slots or perforations are assembled on the shaft. Holes or cuts are made in the sheets, which are called keys (for collecting a package of sheets into one design).

The number of revolutions of the motor stator determines the number of holes or slots in the rotor. Holes or grooves contribute to the creation of short-circuited squirrel cage. The coils are formed by pouring in them a low-melting metal with high electrical conductivity under pressure.

A device of a short-circuited type during operation is exposed to destructive forces. The following nodes are subject to it:

• iron package
• shaft bearing units;
• rods fill coils.

Engine repair tools.

Breakage of the last elements among the faults of the asynchronous motor type is no more than 0.3-0.5%. Due to a breakdown, the heating of the equipment is enhanced, the power of the electric motor is lost, the current consumption increases by a factor of 5-6. The absence or failure of protective mechanisms contribute to the breakdown of the electric motor. A failed device can not be replaced by a new analogue by performing a stator repair. Pre-diagnostics device. It is performed in 2 ways.

There is equipment on the market that helps to test collector electric motors for the presence of short-circuited coils in the winding. With the help of such devices you can perform a breakage test of a low-power rotor.

Another method is to connect the transformer to short-circuiting rings. Voltage on the secondary winding should be 1-3 V. Metal filings are poured on the surface of the rotor. Paths formed along the rods will indicate their integrity. Otherwise, their integrity is violated.

Full diagnosis

Inspection of the stator and central parts of the electric motor is performed on special trestles with 2 rollers in the upper part, which facilitate the turning of parts.

In order to independently repair the rotor, it is recommended that you first familiarize yourself with the documentation, determine the operating time of the bearings and detect unresolved defects.

The scheme of dismantling rods short-circuited rotor winding.

Work is performed using a set of keys, a tester and lifting mechanisms.

The motor is disconnected from the network. The equipment is cleaned with brushes from dirt and dust and blown with compressed air. The fastening screws on the lid of the terminal box are unscrewed, the lid is removed, the wires are disconnected. The cable must be disconnected while observing the bend radius so that it remains intact. Fasteners and small parts are recommended to be put in the box from the toolbox in order not to lose.

Inspection of the stator and the central elements of the equipment is made after its removal and cleaning. In the rotor, the condition of the metal elements, the fastening of the steel to the shaft, the core of the balancing weights, the condition of the short-circuited winding and the fans are diagnosed. Balancing weights must be fixed. The density of pressing of the stator steel is checked similarly to the rotor. It is recommended to check the integrity of the welds and the steel fastening density. Defects of welds are eliminated by welding.

In fans, it is necessary to check the integrity and reliability of the blades. They are tapped with a hammer weighing 0.2-0.4 kg. Poorly fixed or cracked blades make a rattling sound when tapping. Broken blades are replaced by new analogues. The position of the fan before removal for inspection is marked on the rotor, so that when it is reinstalled (after checking), it is replaced in its original place without disturbing the balance.

Repair the rotor.

The density of the landing of the last elements allows you to determine chasing. It is carried out with a sharpened chisel with a rectangular working part. The sharpened part of the width should be less than the width of the groove by 1-1.5 mm. Mobility and rattle rods indicate insufficient planting density. The weakened parts are minted along the entire length so that the rectangular part is riveted, with which the gaps between the walls of the grooves and the rods are filled, which are inspected after defects for defects. Visual inspection and tapping allow you to define only a complete break. The presence of cracks in the ring or rods indicates the need for repair.

Repair work

Repair of the structure is performed to restore its performance and requires the replacement of individual parts. Repairs are carried out in the workshop or on site. In the process of repair is carried out:

• dismantling;
• cleaning;
• disassembly;
• restoration of the terminals, damaged sections of the winding and the terminal box;
• replacement of bearings;
• painting;
• device assembly;
• tests under load and idling.

Equipment with phase-type parts requires additional repair of the brush-collector mechanism. At the site of the crack, the core is cut and a hole is drilled from the cutting point to the outer end of the shorting ring. The depth of the hole is 6-7 mm, and the diameter is equal to half the diameter of the rod. The drilled part is filled with copper alloy.

The gaps between the filler and the end of the metal peg should be 0.2 mm, and when soldering with silver solder - 0.1-0.15 mm. Copper-phosphorous solder is used to repair electric motors with light start-up conditions and a peripheral speed of less than 50 m / s.

Solder silver Psr-45 is used to repair the stator and the central elements of the electric motor. Psr-45 is used for repairing equipment that is operated under severe starting conditions, subject to temperature stresses at the point of connection of the shorting ring with the rod and for units with a peripheral speed of 50 m / s.

Soldering is carried out using 2 burners: the first is working, and the second is necessary for heating and maintaining the temperature of the ring and rods. The rotor in the process of soldering is placed vertically.

Solder is melted after heating to the required temperature of the core, ring and rod. It should not be melted in the flame of a burner. The flux is applied to the surface with a hot rod.

Solder points sawed and cleaned. The quality of work is checked using a micro-meter and inspection under a magnifying glass. A similar variant of the repair of rods is performed if no more than 10% of their number is damaged in the winding. Equipment after repair must be balanced. A large amount of damage in the winding requires its complete replacement. Rings are disconnected by the method of soldering or mechanically. The rods are removed from the slots. After repair, all parts and stator of the electric motor must perform their functions properly.