I need to replace a secondary phase sensor (ST197S). Page 23-43 and 23-44 of the 34SG O&M manual explains how to mount a phase sensor, and the gap is supposed to be 2.0 mm ± 0.5 mm. However, I don’t see any way to get access to the end of the phase sensor in order to set the gap without removing the cover which the phase sensor appears to be screwed into. This seems like it would make measuring the end gap inaccurate or impossible, and I want to know the correct method before removing the cover. I have not yet found any other instructions for setting the phase sensor gap. Am I missing something? Has anyone else replaced a phase sensor yet?
Haven’t done this before but the first thing that comes to mind would be bottom out the sensor, measure the end you can access with a depth mic or calipers, and then add 2.0mm to that measurement by unscrewing it. Will that work? have access to the area around the sensor bore?
We typically run them all the way in and back them out 2 1/2 turns and lock it down. This is approximately under a 1 mm gap. We have found that the spec of 2 mm is too big of a gap and the sensors typically don’t work or work well if the gap is that big.
Correction, I spoke with my electrician and he says to screw it all the way in and back it out 1/2 turn, this leaves a little more than 0.5 mm gap. One full turn is about 1 mm. As I stated before we never had good luck gapping it to the recommended specifications.