Protective relays -- time-overcurrent demonstration

A video demonstrating the operation of a "51" time overcurrent protective relay, in this case a legacy General Electric "induction disk" relay design.

[@deanbartlett2497]

Very good demonstration of the relay. I really enjoyed your explanation. I would simply like to add to your discussion about the seal-in relay. One of the main functions of the "seal-in" relay (SI) is to bypass the spring that resets the disc each time it rotates. Some viewers may not know that when the disc finally closes its contact to trip the circuit breaker, current actually flows through this spring (which is very thin). This current (to the trip coil) can approach 20 amps or more. This much current can easily damage the spring. The SI relay will operate with (0.2 or 2.0 amps) through it, depending on the tap selected, (a screw on the front of SI). When SI picks up it seals itself in through its own contact; the same contact that bypasses the spring. The fact that it displays a RED target is actually a bonus, by taking advantage of the movement of the electromagnetic clapper. The word "TIME" of course indicates that the relay operated due to a "timed" function; (rotation of the disc).

[@JeremyDismukes225]

This is so helpful as my professor literally just hands a manual and expects us to know what's going on. I'm glad to know the working mechanics of this with a diagram to follow. Thank you so much for this video

[@joshshields1242]

Great video and well explained. Thanks to you I now understand something that seemed totally mystifying. Made my day.

[@gjohn1000]

You should make more videos for us students... I was reading some info for my Industrial and Commercial Electrical Systems class on relays and it wasn't making any sense because it was hard to visualize, but you placed everything into perspective especially with the diagram and the engineering jargon used! Thank you very much!! Ps I'll be more than willing to give you Topic Areas for this particular class!

[@larrypatterson3957]

We have a medium-voltage distribution system where I work. I was trying to learn about these relays from the manual and it was difficult to follow. Your video does a great job of explaining the workings of these workhorses. Thanks for taking the time to show us.

[@jedpallan7237]

Thank you

[@Jupiter198276]

Great video. You made it easy to understand.

[@nunez6783]

Really good explanation. Thank You!

[@rajshah4000]

great demonstration!

[@SurgeWorld]

Such a great video

[@88Ghillie]

Thank you from wannabe engineer in London!

[@nickcyr5071]

Great Video!

[@masoudkhamushi9821]

very interesting, thank you very much

[@nqobizizwesibanda8200]

Well explained thanks

[@himakshivyas5687]

Why shape of aluminium disc is not completely spiral, why it is having cut