The latest Charms hardware manual shows a diode around the solenoid coil when connecting to a 24VDC isolated CHARM module. My understanding is this is to protect the solid state switch from the high reverse voltage spike caused by opening the inductive coil circuit. Older versions of the hardware manual did not show these diodes being needed. From those I have surveyed there seems to be a large number of installations that are not using these diodes. While the cost of the diodes themselves is low, the labor to add them to every solenoid on a DCS conversion project could add up quickly. My question to this forum is are you actually installing these and if not have you had any issues? FYI - the typical diode called out for this is a 1N4007.
In reply to David Tudor Evans:
Sal Salamone PE MBA | Application Engineer
Novaspect Inc. | 4415 W Lawrence St. | Appleton | WI | 54914 | USA
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