Recent content by mtwentyc

Waross, thanks - we started that thread in 2007 and have linked it above. As mentioned we were never able to conclusively determine that we had an AC ripple. We're looking for help understanding how (if we did) ripple would actaully cause this phenomenan, or what other external factors might...

Gunnar, agree this would be a good test to do however clamping pigtails is difficult for us as we are on a gas platform, the pumps are located in a Zone 2 area and operating motors whilst open (un-purged) is not allowed. Oftenlost - Motors are actually GEC Unirigs, rated at 800hp each, two per...

Ref thread237-178054 Hi all, back again after a significant absence. Apologies in advance to begin a new thread with such a long ramble, hopefully you'll see how frustrating this is as you read on. Mid 2006 - The issue referenced in the above thread (Feb '07) related to extreme and selective...

Skogs, thanks for your input, I'll look for the new thread. We're still trying to find teh fault, will post when have some new info Cheers

Thanks all, assignments on the SCR have been changed and tested (this one will drive a mud pump as well), no signs of similar brush wear on the pump (but they are a different style of dc motor), this supports the waveforms on SCR outputs, which show OK. Present thinking is that we have a field...

Thanks Gunnar, appreciate it. Anyone else seen this before?

Thanks again all - Can't pull brushes and test as are currently between drilling campaigns, in fact cannot simulate any load at all now, so have to fix before the next well begins....... So how do we find this ripple if it is the cause? We did take snapshots of SCR output wave forms (on a low...

No - it's a standard hi-torque 752, has a spiral grooved comm, four axially arranged brusholders with three brushes per holder. Is vertically mounted and very typical, thousands in use in similar drilling applications around the globe. Vibration seems so unlikely to me, no evidence of any nor of...

Thaks all; Spring pressures all Ok - hace replaced the drive three times with a new unit each time due to flashover risk in open hole, problem so bad eventually comm was worn on the section closest to the armature windings. Problem does not follow motors, it stays with the TDS. Also, machine in...

Hi all, thanks for the forum. Have searched by keyword with no results - maybe someone has seen this problem before. We have a 1000HP GE752 AUT, series wound in an offshore drilling environment. The motor is mounted vertically on a top drive drilling unit driven by a Ross Hill SCR system. I'm...