Starting Capacitor in non-motorized devices.

Thread Starter

Fabian1421

Joined Mar 29, 2022
6
Hi, I have a question to solve.
Why should an starting capacitor only be used in single-phase motors and not in devices non-motorized, for example, a television?
The starting capacitor protects the motor, I would like to know if the starting capacitor is equally useful in protecting devices such as televisions or non-motorized devices where the voltage has many peaks that damage electronic devices.
 

MrChips

Joined Oct 2, 2009
26,099
Welcome to AAC!

A motor is a mechanical device. It has mechanical inertia and needs a push to get it moving.
An AC motor works on AC voltage and current. The starting capacitor shifts the phase between the current and voltage. This phase shift is what is used to get the motor started.

There is no start capacitor required in other electronic devices. Yes, they do have inertia in a sense that storage capacitors need to charge up from zero charge. This causes an initial surge in the current at power on. There are ways to handle this initial current surge but it is nothing as giving it a push start.

There is a huge difference between the two devices. There is no comparison.
 

Thread Starter

Fabian1421

Joined Mar 29, 2022
6
Welcome to AAC!

A motor is a mechanical device. It has mechanical inertia and needs a push to get it moving.
An AC motor works on AC voltage and current. The starting capacitor shifts the phase between the current and voltage. This phase shift is what is used to get the motor started.

There is no start capacitor required in other electronic devices. Yes, they do have inertia in a sense that storage capacitors need to charged up from zero charge. This causes an initial surge in the current at power on. There are ways to handle this initial current surge but it is nothing as giving it a push start.

There is a huge difference between the two devices. There is no comparison.
Thank you very much for your answer.

If I put a starting capacitor to a TV, will the TV's circuitry be damaged?
 

Ian0

Joined Aug 7, 2020
5,132
It doesn’t protect the motor. It shifts the phase to generate a rotating magnetic field, so that the motor can start up (and start up in the right direction).
Once it has started, as oscillating magnetic field is sufficient to keep it running.
 

MaxHeadRoom

Joined Jul 18, 2013
25,211
Hi, I have a question to solve.
Why should an starting capacitor only be used in single-phase motors and not in devices non-motorized, for example, a television?
The short answer is a TV does not require a phase shift to get it going.
A single phase induction motor however does, and using a capacitor is just one method of obtaining it.
 

GetDeviceInfo

Joined Jun 7, 2009
2,095
The capacitor neither protects nor starts a motor. A capacitor may exist in the starting circuit of a motor, but it’s function is only to phase shift for the start winding. It’s this shifted phase winding that leverages the start. In general electronics, particularly when using ICs, capacitors are used frequently to provide a smooth power source, buffering dips and spikes. This is done extensively.
Rather than using a capacitor, you’ll often find an inductor doing what you may be considering. This inductor is often a integrated into appliance power cables. Ferrite filters, or chokes, are used to arrest spikes and line noise.
 

MaxHeadRoom

Joined Jul 18, 2013
25,211
The capacitor neither protects nor starts a motor.
I disagree!
A capacitor or other is used to start the induction motor rotation, if a capacitor or other method is not used, the resultant field just oscillates across 180°, the result is no rotary motion.
With potential burn-out of the motor.
 
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GetDeviceInfo

Joined Jun 7, 2009
2,095
I consider ‘starting’ to be work. A considerable amount of work to get a load up to some speed. The work itself is the current and subsequent magnetic field of the offset winding. Can I power that winding through a capacitor. Sure I can, and it’s one of the most practical ways, but I can do it with other methods as well, suggesting that a capacitor is not the actual ‘starting’ device. Misunderstanding that might leave one to believe the capacitor has special powers that can be applied to all kinds of things like tv and such.
 

MaxHeadRoom

Joined Jul 18, 2013
25,211
Open to interpretation!
In my opinion, the 'Start' capacitor is one of the devices used in the starting process of a squirrel cage induction motor. Simple.
Without being pedantic, All the OP wanted to know was how come it is not used in other devices.
.
 
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