Recent content by knights of 3

I wanted to test the theory of capacitive coupling, so I had a control XFMR laying around and wired up on the bench. I plugged in 120 from the wall outlet and set it up to put out 60 on the secondary winding. I did NOT ground the secondary output. I took a fluke DMM and went from X1-X2 got 65...

Like I said this circuit cannot be tagged out right now due to its importance. so I can't take resistance readings. I am looking for the ENGINEERING THEORY or formulas of why I am getting 80 v to grd from one leg and 40 V to grd from the other leg. We all kind of agree the reason is because...

Hi all, One of my guys was working on a control ciruit for a fan bank. The control circuit in powered by a 480-120 V control xfmr. His voltages from x1-x2 were 123 Vac. Across all energized relays: 123 Vac. But when he took voltages to ground he got around 40 Vac from the X1 bus to ground...

CS, Thank you for your reply. Almost everyone I talked to instantly defaulted to "a 3-phase motor CAN'T re-start once single-phased." Thank you for clearing up the distinction in theory between a loss of a line phase and the loss of a motor winding.

Can anyone with an engineering background explain to me if it this theoretically possible? I understand a motor won't start when one phase of voltage being supplied from the source is lost due to a blown fuse, a bad contact or even a destroyed overload heater. The motor will only have a...

There is an overhead door at work that will start to open but then stops. I don't know all the details because I haven't been out to the door yet, but the information has been given to me by one of my guys. The door is driven by a 3-phase 480 volt motor. I don't know anymore information...