Overload Protection for Single Phase Induction Motors

GA. Up to a point though it is important to bear in mind that the real job of the fuse is to protect the wiring that feeds the motor.

In addition to the above:

• Thermistor, embedded in the windings, and trip relay outside them.
• Thermostat on the surroundings.
• Mechanical weak link.
• Belt drive.
• Etc.

However, it is best to design whatever the motor the motor is driving in such a way that overload does not occur in the first place.

• Proper design.
• ...

• A limited-slip clutch between the motor and its load.
• On Garrard (usual disclaimer) and other transcription turntable decks used in discotheques and in radio broadcast studios, one of the ways of preventing the motor from overloading is to introduce a felt slip-mat between the vinyl disc being played and the turntable itself. The presence of the slip mat has a distinct advantage when cueing up: the stylus can then be advanced closer to the track being played. The technique is then to start the turntable while holding the slip mat stationary, open the fader fully, and the moment the track is needed in the mix just let the slip mat go. It helps to have a stylus tracking weight in the 3-5gm region, so as to reduce the risk of the stylus jumping out of the groove in the record while the mat is being slipped, which can mean using a special cartridge and stylus while using slip mats. With a little practice the results are quite staggering and can turn a crap DJ into a very capable one.
• ...

It depends on your context here. Are you designing a single phase motor from scratch and want to incorporate the overload protection into jthe motor? Or are you going to USE a single phase motor and want to make sure it is protected?

If using an off the shelf motor, fist check to see if the thermal overload protection is built-in. That is very very common on single phase AC motors. If it is, then all you need is Short Circuit protection, ie fuse or circuit breaker. Here in North America, motors that have built-in thermal overload protection are required to state so on the nameplate. The wording may be slightly different between brands, and sometimes it is just abbreviated as something like "TP" for Thermally Protected, but it has to be there. If there is nothing explicitly saying that, then you must use an external overload protective device.

As far as external thermal overload devices go, the simpler the better. Where you are in the world will make a difference in what is available to you, so rather than all of us spouting off ideas that may be irrelevant to you, how about you saying where you are, what size motor you are referring to and what voltage you intend to use? Don't make is play 20 questions...

A fire extinguisher?

A suitably sized adjustable thermal overload relay. Since overload will result in thermal failure of the motor, a thermal relay will replicate this. However, since the thermal mass of the relay is very much smaller than that of the motor, a suitable ambient compensation should be there. Somewhat slightly under-compensated.

Impedance protection; it requires no additional circuitry/components, just careful design. If you insist on using additional complications/components then try a PTC (Positive Temperature Coefficient) thermistor/varistor or eutectic thermal switch embedded/in series with the run winding.

Have a bad vacuum cleaner motor circuit. The Thermal overlord device is now an open circuit. Where do I get a new one? E-bay? Amazon?

Two products you should NOT use: 1) anonymous requests for help, and 2) using abbreviations for words that are not typically abbreviated.

The first makes the reader think you are ashamed of asking for help, or that you are asking something your boss thinks you are already an expert at.

The second makes you look like an idiot. It's four more keystrokes, to go from 'Pl' to 'Please' and you'll find people are nicer to you and less snide when you ask politely instead of hacking off most of the 'polite asking' word like you don't care.

I recommend you below two big company;

Thermal overload relay (TA series) of Contactor from ABB

EOCR from Schneider

And if you wanna make it gorgeous, UMC100 from ABB or Tesys T from Schneider is good for you.

Hope it help you.