Motor overload protection

[cssg]

Has anyone any circuit diagrams for a simple auto resetting overload breaker for a reversible AC motor (240v 500w). This is to work as an electronic clutch. (The auto reset delay must be adjustable so that the motor cycle timer will cut off supply before the reset tries to start the motor again.)
Any help would be much appreciated!
Thanks

 

[diskullman]

Maybe look into a UST shock relay

http://www.ustsubaki.com/ptc/opd.html

Russell Giuliano
Unique Technologies Associates - Cobra Solid Lubricant

http://www.uniquetechnologies.com

 

[Barry1961]

Could you add a timer to an electronic overload?

Barry1961

 

[jraef]

You need to define if this is to be a motor protective overload situation, i.e. I²t overload, or a machine over load, i.e. shock loading situation.

If it is a motor overload protection situation, you cannot (or should not) reset the overload until the motor has cooled down. Most Overload Relays now have an Auto-Reset function built-in, and as Barry1961 mentioned, you can add a timer to it if you want even more time.

If it is a shock loading or jammed load situation, and you are planning on reversing the motor to clear the jam, that is an entirely different situation, and FYI, you should not refer to that as an "overload" because that has a specific meaning in motor terminology. A device like the one posted by diskullman is what you want there, and there are dozens of them available on the market. They are called Current Sensing Relays, Jam Relays, Electronic Shear Pins, Shock Load Relays, there are many other terms used. Many of them have built-in timers as well. Google those terms and you will get plenty of resources.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[cssg]

Guys
Many thanks for pointing me in the right direction
Yes, once you know the jargon you can google it sensibly
Very Many thanks
Simon