I have encountered a situation with GE motor starters where the OL selection chart for a size 5 starter with CTs and a 168 Fla at 150 hp calls for almost a double size heater element than what would be expected with a 5 amp secondary current on the CT. The heaters recommended by the chart would...
I was able to locate Wescode C385P SCRs from a supplier. We now have the inverter running but this is only until this inverter gets retrofitted with IGBTs by the OEM or we buy a new one. Hopefully certain people will learn that paint that is still glossy in not the only metric for figuring...
jraef, I got the "invertere grade" from a Powerex rep. when I give him the device numbers. My experience is with DC motor drives and I know what a phase control thyrister is but the inverter grade stuff was new to me too.
I would like to know what electrical parameters make the difference between a inverter grade thyrister and a phase control thyrister? I am tring to cross refrence an old obsolete inverter grade thyrister in an attemp to make a quick repair to a UPS system at my facility that has a shorted scr in...
I need to know which codes,API or ANSI ect., cover the installation of compresion and threaded steel tubing used in high pressure hydrogen gas service. This information is needed after an incident where a maintenance technican changed several 3/8" tubing valves in a valve/regulator tree fed by...
Thanks for the info electripete! I am tring to "up" the skills of our technicians by introducing them to the concept of the phase-to-phase short ( I'm tired of the "Megger Test" being the final and only word on motor falures in my plant which thus causes un-needed drive change-outs ) and I...
waross, you are right about the troubleshooting being challenging. It was a troubleshooting situation that an electrical contractor was working on, with dificulty, that brought the fact that there are 120ac control ciricuits that are switched on the neutral to my attention. To my supprise our...
In the United States. The two facilites are Japanese owned and we have had some isues with differing approaches as far a technical issues go(Code be damned). We do use some positive-common DC and I think this is where some inexperienced person who didnt understand the difference with AC and DC...
Does anyone have experience with switching the neutral instead of the "Hot" conductor in control circuits except in motor starter buckets. I have encountered this practice on a DCS system in a chemical manufacturing facility.I am told this is a safer practice in that all conductors in the field...
It looks as though the motor continued to run and as for uneven torque on the weather head I doupt that was an issue because the nearest conduit body (3") also blew its cover. This cover was sheetmetal and was bent to hell. Again no carbon or signs of arcing. It will be interesting what the...
I have seen ground faults inside junction boxes at MV motors do a good deal of damage to the enclosures.(There have even been reports of fatal injuries to people near the motors when such happens.) Lots of "arc" damage will be present but not with my newest MV fun! In the most recent incident...
Why would a medium voltage (2300v)AC variable speed drive have a dual secondary (6 leads out) supply transformer feeding the the front side (12 pulse rectifier)of the drive?
Is this transformer needed of does it serve some added benifit?
Could you describe what type of load you are driving? I would expect to see more than a 21amp no-load from a 4 pole motor at 1750 unless there is some type of stored mecahnical energy, such as a flywheel, "helping the load" in the system.
