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What will happen if the starting capacitor is broken_What will happen if the motor capacitor is broken?

Views: 3     Author: Site Editor     Publish Time: 2023-11-22      Origin: Site

Starting capacitor is an AC electrolytic capacitor or a polypropylene or polyester capacitor used to start a single-phase asynchronous motor.So what will happen if the starting capacitor is broken? Will the motor still run if the capacitor is broken? How to replace and repair, what should you pay attention to?

How to judge whether the starting capacitor is broken

1. Look: Check whether the capacitor is bulging or swelling;

2. Listen: Connect the motor and listen to see if there is a buzzing sound from the motor. Turn the rotor by hand to rotate slowly and weakly;

3. Smell: Some capacitors are burnt due to excessive current and have a burning smell on the surface (limited to capacitors with plastic shells);

4. Use a multimeter to measure the capacitance.

The single-phase current flowing through the motor cannot generate a rotating magnetic field, so a capacitor is needed to separate the phases. The purpose is to produce a phase difference of nearly 90゜ in the currents in the two windings to generate a rotating magnetic field.

Capacitive induction motors have two windings, the start winding and the run winding. The two windings are 90 degrees apart in space.A capacitor with a large capacity is connected in series to the starting winding. When the running winding and the starting winding pass through single-phase alternating current, the current in the starting winding is 90 degrees ahead of the current in the running winding due to the action of the capacitor,reaching the MAX value first.Two identical pulse magnetic fields are formed in time and space, causing a rotating magnetic field to be generated in the air gap between the stator and the rotor.Under the action of the rotating magnetic field, an induced current is generated in the motor rotor. The current interacts with the rotating magnetic field to generate electromagnetic field torque, which causes the motor to rotate.

To make the single-phase motor rotate automatically, we can add a starting winding to the stator. The starting winding and the main winding are 90 degrees apart in space.The starting winding should be connected in series with a suitable capacitor so that the current in the starting winding is approximately 90 degrees out of phase with the main winding, which is the so-called phase separation principle.In this way, two currents that are 90 degrees different in time are passed into two windings that are 90 degrees different in space, and a (two-phase) rotating magnetic field will be generated in space.Under the action of this rotating magnetic field, the rotor can start automatically. After starting, when the speed rises to a certain level, the starting winding is disconnected with the help of a centrifugal switch or other automatic control device installed on the rotor.During normal operation, only the main winding works.Therefore, the starting winding can be made to work in a short time.But many times, the starting winding is not disconnected. We call this kind of motor a capacitive single-phase motor. To change the direction of this kind of motor, it can be achieved by changing the position of the capacitor in series.

Common causes of damage to the starting capacitor are:

1. The voltage is too low;

2. The load is too heavy; the speed is low and the engine starts repeatedly or the engine takes a long time to start.

3. Impact of the peripheral environment; such as installing near a heat source in a place with poor heat dissipation or in a humid working environment.

4. Poor contact and poor capacitor wiring can also easily cause the capacitor to burn out;

5. Centrifugal switch sticking (single-phase motor with centrifugal switch)

Precautions for repairing starting capacitor:

1. Find out the cause of the fault;

2. Capacitors of the same capacity and model can be purchased and replaced;

3. When you cannot find a capacitor of the same model, look up the parameters of the capacitor and replace it with a capacitor with the same parameters that can be found.

Will the motor still run if the capacitor is broken?

A bad starting capacitor will cause the motor to fail to start. If it is powered for a short time, it will only make a buzzing sound, causing the current to rise sharply. If it is powered for a long time, the winding will seriously overheat and burn the motor. So it should be replaced immediately.

Precautions for starting capacitor replacement:

1. When dealing with or replacing a faulty capacitor, disconnect the power supply to the capacitor, turn off the switch or unplug the plug, and discharge the capacitor.

2. After the capacitor is discharged, there will still be some residual charge that cannot be discharged for a while, and it should be artificially discharged again.

3. When discharging, first connect the grounding terminal of the grounding wire, then use a grounding rod to discharge the capacitor several times until there is no discharge spark and discharge sound, and then fix the grounding terminal.

4. Because the faulty capacitor may have poor lead contact, internal disconnection or blown fuse, some of the charge may not be exhausted. Therefore, maintenance personnel should wear insulating gloves before touching the faulty capacitor and short-circuit the two poles of the faulty capacitor with a shorting wire before disassembling and replacing it.

5. For those using multiple capacitors in series, they should also be discharged individually.


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