safety relay yellow wire

[queenslegs]

Resurrecting this thread (out of general interest) since I can't for the life of me understand how an ac voltage from one of the three white stator winding wires can hold a dc relay coil (safety relay via yellow wire). Without a diode and some capacitance to smooth things out of course!
What am I missing?

 

[mrriggs]

The current is alternating faster than the relay can react.

 

[retiredgentleman]

Who said the Safety Relay is a DC relay?

Since its energized from an AC alternator, I've always assumed that Yamaha used an AC relay.

The difference between a DC relay and an AC relay is the presence of the Shading Coil. In AC relays, the alternating current supply changes direction about 120 times a second. At each instance, when the sine wave passes through zero, the current flowing through the coil becomes zero. This results in a loss of magnetism for a few milliseconds. When this happens about 120 times a second, the repeated drop and pickup of the coil produces a noise known as chattering. This also leads to the making and breaking of the relay contacts leading to disturbances in the connected electric circuits.

A shading coil is a coil with high remanence. thus when the magnetism of the coil collapses when the current becomes zero. The shading coil still retains the magnetism. Thus, ensuring that the contacts do not drop off.

 

[queenslegs]

Thanks RG, where there is a question, there is an answer!

 

[CZ650]

I know this is a dead post and all, but it's a good one. I can say that when I tied the relay into a PMA wire, it chattered as described above. I foolishly rode it that way anyways and blew the relay out in a day. Currently have the relay bypassed but Im going to try using modern relays to bring back the often hated bells and whistles of my special.