April 29, 2014 by Kevin Keras
Problem Solved - The Mystery of The Plate Sealer That Wouldn't Seal
Okay, so several of you have gotten impatient and sent me emails asking for the solution to the plate sealer mystery in my last post. As is often the case, the answer was simple but it was not obvious...a perfect storm of causes, if you will.
Let me cut (no pun intended) to the chase. The major factor was AC power...or lack thereof. Although the measured power coming into the unit was within spec for the instrument (112 VAC), the user also had a JunAir compressor on the same circuit...as well as a large refridgerator and a centrifuge. The combination of the sealer holding temp, the JunAir running almost continuously (due to a slight leak), the fridge compressor running and the centrifuge...centrifuging, resulted in a transient line voltage drop down below 100VAC. This was only measurable using a chart recorder which monitored the true RMS voltage. While the electronic display of the sealer operated and made it appear that the sealer was functioning, the timing of the pneumatics was not correct. The cutting bar would advance but retract before cutting action could take place. Because the JunAir runs quietly, it was difficult to see that it was pretty much always running due to the leak. We believe the fridge compressor kicking on while the compressor piston was the bottom of it's stroke is where the power drain occurred.
Isolating the sealer and the JunAir (fixed the air leak) from the circuit in question resolved the problem.
Chalk one up for the "doh!" list.