What is Run Capacitor? | Animation | HVAC | Electrical
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- เผยแพร่เมื่อ 8 ก.พ. 2025
- A run capacitor is an electrical component used in various types of motors, such as those found in air conditioners, refrigerators, washing machines, and pumps. It is a type of capacitor specifically designed to provide a phase-shifted current to create a rotating magnetic field in the motor's windings.
In alternating current (AC) circuits, the voltage oscillates between positive and negative cycles. The run capacitor is connected in parallel with the motor's start winding or auxiliary winding and remains in the circuit during the entire operation of the motor. It helps maintain the phase difference between the main winding and the auxiliary winding, allowing the motor to start and run efficiently.
When the motor is powered up, the run capacitor stores an electrical charge and releases it at the appropriate time during the AC cycle, helping to improve the motor's power factor and efficiency. This phase-shifted current aids in the continuous rotation of the motor's magnetic field, which is essential for the motor's smooth operation and constant torque production.
Run capacitors are rated in microfarads (μF) and typically have capacitance values ranging from a few microfarads to tens of microfarads, depending on the motor's design and power requirements. They play a vital role in the operation of single-phase induction motors, helping them overcome the lack of a rotating magnetic field present in three-phase motors, which inherently have balanced phases.
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Its crazy in Engineering when i did they only told us what a Capacitor does. They said it was to store charge but never gave a practical use of the capacitor.
Thanks for explaining the Start Capacitor and Run Capacitor.
Your illustration is for DC, most compressors are AC. A capacitor across an AC circuit doesn’t store voltage because the voltage is changing positive to negative sixty times per second. A capacitor will introduce reactance into the circuit.
I'm planning to make another video on the same topic, which is explaining everything clearly.
@@zebralearningscan the AC capacitor cross the circuit work or not.
This animation is based on DC power source. HVAC compressors don't usually work with DC power source. The purpose of the capacitor is to provide reactive power for magnetic field genaration inside AC engine during startup.
Good morning sir your videos are very informative and attractive
Thank you so much, and I'm glad you liked it.
Thank you for the simplicity. My question is, is the start capacitor the same with run run capacitor, or are they different?
They start different. Start capacitors are used to give the extra torque to start the capacitor and run capacitor is used to keep the unit run efficiently.
How to find which one start capacitor and which one is run capacitor
Pretty late to the comments but start caps are usually much higher mfd rated. The run cap will usually be like 80 mfd and a start will be something like 325. But in an hvac unit make sure not to confuse the fact that there is two caps with them always being a start and run. You will also usually have a fan cap that is 5-7.5 mfd.
Dear sir I am working in hvac since 2006
That's good. So you have good experience.
I wish someone would explain how the start capacitor is taken out after the after the motor starts. I thought the capicator can change the direction of the motor, plus boost the motor voltage to start. The motor has a centrical switch in the motor to take out the start capicator after starting?
It depends on the setup. Most times in hvac a start capacitor and run capacitor are run through a potential relay and once sufficient voltage is seen on the start winding the relay opens and disconnects the start cap but leaves the run cap intact. Less common in hvac but more common in other large single phase motors would be that the start cap is wired to a centrifugal switch in the motor that pulls open when the motor starts spinning and disconnects it from the winding.
You are correct with a small difference from what info I have.From my knowledge i thought they were ingaged when high amp is drawn from the start winding. And disingage when amp is lower in the start winding because the compressor has spunn up. And therefore it is very important to have the right relay. I am 99% certain of this in fridge and freeze compressors. Mabi we both have right and there is both kinds of relays.
So I deal mostly with 3hp and larger compressors. Most are 5 but I work on some screw compressors in the 15 to 30hp range. Seldom do I work on reciprocating compressors that have a hard start and need a start relay but when I do I have to use a different relay for 3 vs 5hp basically I think the windings take a bit larger to get the voltage but all the relays are still just looking for a certain voltage off of the start winding (probably 120). Really all you are looking to do in a reciprocating compressor like a fridge or a freezer is get the first crank or two because those will require much more torque to get moving than once it is moving, warm, and has some oil circulation.
Please in hindi language