sdowney717
Member level 1
I was given an old Onan MCCK marine generator.
The K7 relay-emergency device is crushed so beyond repair, and these parts are long ago out of production.
What I would like to do is design something that would function in a similar way.
The way the device works is if low oil pressure (LOP) switch S4 conducts from loss of oil pressure, power flows to a thermal time delay device (K7) connected to ground , (functions like a thermal breaker), after 1 minute, the device trips open cutting power to the generator off-on-off switch S1, so it turns off like you flipped the switch to off. the k7 device is in circuit before the S1 switch with one end connected to B+ battery voltage.
The "emergency relay" K7 device has 4 wires connections, two for the heater circuit to trip it off, two for contacts that cut the power. A red button pops out and after it cools this can be manually reset.
I took good pictures of the wiring diagram and schematic, originally drawn up in 1968
If I bypass this shutdown control, and the gen ran out of gas, or overheated, or had low oil pressure, it might kill the ignition, but it would crank till the battery went dead.
I was thinking maybe a timer circuit instead of the heater circuit, say after a minute of time it could cut power to the generator at the S1 off-on-off switch?
What I need is someone to look here and tell me how I can do this.
Thanks
K7 relay shows up in lower left of picture, S1 switch lower right on the wiring diagram.
If the timer then kills the power to the gen , perhaps this could be made so the reset would simply involve moving the off-on-off switch off and then on again? Instead of a button that pops out?
And if a relay gets involved, in an error condition, you would not want it consuming power.
So I need some ideas on how to make something else work here.
edited version of the photo that is brighter than original.
The K7 relay-emergency device is crushed so beyond repair, and these parts are long ago out of production.
What I would like to do is design something that would function in a similar way.
The way the device works is if low oil pressure (LOP) switch S4 conducts from loss of oil pressure, power flows to a thermal time delay device (K7) connected to ground , (functions like a thermal breaker), after 1 minute, the device trips open cutting power to the generator off-on-off switch S1, so it turns off like you flipped the switch to off. the k7 device is in circuit before the S1 switch with one end connected to B+ battery voltage.
The "emergency relay" K7 device has 4 wires connections, two for the heater circuit to trip it off, two for contacts that cut the power. A red button pops out and after it cools this can be manually reset.
I took good pictures of the wiring diagram and schematic, originally drawn up in 1968
If I bypass this shutdown control, and the gen ran out of gas, or overheated, or had low oil pressure, it might kill the ignition, but it would crank till the battery went dead.
I was thinking maybe a timer circuit instead of the heater circuit, say after a minute of time it could cut power to the generator at the S1 off-on-off switch?
What I need is someone to look here and tell me how I can do this.
Thanks
K7 relay shows up in lower left of picture, S1 switch lower right on the wiring diagram.
If the timer then kills the power to the gen , perhaps this could be made so the reset would simply involve moving the off-on-off switch off and then on again? Instead of a button that pops out?
And if a relay gets involved, in an error condition, you would not want it consuming power.
So I need some ideas on how to make something else work here.
edited version of the photo that is brighter than original.
Last edited by a moderator: