monkeyhead
Member
Lost an output on a Micrologix 1500 the other day. Had several spares so I just re-assigned it. When I went to update the schematic, there was a note indicating that the same thing had been done about 3 years ago. The machine was roughly 4 years old at that point.
It's a relay output on a 1764-24BWA base driving a 24vdc, 5.4 watt, solenoid valve.
My first thought was that I should put a diode in to protect the contacts against the reverse voltage spike when the coil's magnetic field is collapsing, but I'm beginning to feel like this might be a plain ol' mechanical failure.
The valve can be cycled as many as 40 times a minute with a 450msec pulse. A rough estimate is 15 million cycles over the last 3 years.
What do you cats think?
It's a relay output on a 1764-24BWA base driving a 24vdc, 5.4 watt, solenoid valve.
My first thought was that I should put a diode in to protect the contacts against the reverse voltage spike when the coil's magnetic field is collapsing, but I'm beginning to feel like this might be a plain ol' mechanical failure.
The valve can be cycled as many as 40 times a minute with a 450msec pulse. A rough estimate is 15 million cycles over the last 3 years.
What do you cats think?