This article begins by explaining the working principles of Motor start capacitors first, and then details the phenomena, causes, and experimental methods of starting capacitor failures.
How do primary capacitors work?
Single-phase power supplies differ from three-phase power supplies in that they generate a three-phase magnetic field that rotates in the motor.The starting principle of a single-phase motor capacitor is to use the principle of propelling a current 90 degrees into a circuit capacitor to generate a magnetic field at an angle of 90 degrees to the main wind of the starting wind so that it remains. .. 90 degree rotation angle of the motor. In other words, the magnetic field uses the phase displacement principle of the capacitor to convert a single-phase power supply into a two-phase 90 degree power supply and a 90 degree rotating magnetic field. The other is create by the engine
From this point of view, it may be easier to understand. The starting capacitor drives the motor to start it, allowing the motor to transition from transition to rotation. Otherwise, when starting a single-phase AC motor, it will vibrate from the source instead of rotating. Since the primary capacitor is a two-phase AC motor, no force can be apply to the rotor without a magnetic field, and of course it cannot rotate.
Reasons to start burning Motor start capacitor
In general, the starting capacitor has a very short operating time, and since the centrifugal switch is discharge at the time of starting without generating a leakage current through the starting capacitor, it is difficult to burn. However, even if smoking is not easy, it does not mean that you will not get burn.
If the starter capacitor runs out, the possible reasons are:
- Since the capacitor has low voltage or low quality resistance, it is best to use a withstand voltage capacitor of 500V.
- Normally, when the centrifugal switch is turn off, an arc is generate. The switch can burn the engine. Once the switch is turned on, it cannot be turn off. Current always flows through the capacitor. Secondary motor windings and starting capacitors burn easily over time.
- The power of the selected capacitor is too low, and the starting current exceeds the allowable value of the capacitor.
- The engine is dull or the bearings are damage. It is difficult to start the engine for a certain period of time with the centrifugal switch. It is difficult to reach the stop speed, and the starting condenser burns easily.