We have a small power distribution transformer that is showing relatively high levels of PD (600pC) and we are trying to determine the cause. The transformer is less than 3 months old. Last night we pressurized the unit to 10psi and the PD level dropped to 200pC. My thoughts are this is a...
I'm sure many people have issues like this, so I am asking for opinions on what I should do about my situation. I am a young engineer and therefore I am looking for advice of those more experienced and wiser than I am.
A little background:
I have headed up a new department at work for...
I'm not sure if this is the correct place to post this, but I have recently been tasked with training all of the employees in a power transformer manufacturing facility. I am supposed to teach a course on basic electronics and a course on power transformers. Basic electronics is easy. There...
Our facility has recently had problems with failed cable crimps. Failure causes have ranged from workers forgetting to remove the varnish from the CTC (continuously transposed conductor) wire before crimping to improper fill of crimp joint, to incorrect crimp head selection.
The problem is...
I have a few questions for the MV cable experts out there regarding compliance testing of shielded MV cables. We have a mobile substation in the U.S. with 9 - 500MCM - 15 kv shielded cables, 3 per phase. These are fed from the mobile substation by 6 bare copper (2 per phase) 500MCM cables...
It appears I have just found myself in an all too familiar situation which I can never seem to get out of correctly and this time it's high profile, so I need a little advice. The problem is that I have much responsibility and not enough power to change it.
Here's the situation: I'm heading...
In the last few years I've had issues with older 4 cylinder Japanese motorcycles becoming unstable above 75 mph. The years where this was the worst are between 1975-1984. Several of the bikes had ecessive play in the swing arms in the rear which needed to be ground down (namely the Honda cb650...
I'm having a problem with a control system which requires speed control of 2 fans for coolers on a 25 MVA transformer. The fans are 5 hp and will be run at two frequencies: 45 hz and 60 HZ. The manufacturer has suggested using a VFD to achieve this. However, I really don't have the room in my...
What is the optimal distance between the feed points for a 910 MHz halfwave dipole antenna? Should they be as close as possible, or is there an optimal distance? The antenna will be fed via either RG316 or RG178 coaxial cable.
Forgive the seemingly simple question as I am a newbie when it...
I have been trying to find a good electrically conductive grease for our copper to copper bus bar and power connectors. I'm just wondering what other electrically conductive lubricants are available that are for use in electrical bonding. Most of our bus bars are tinned at the connection...
I have a question regarding a mobile substation we have. The sub is a 230kV, 25 MVA 2 part mobile unit. The transformer is an odd design with the high voltage bushings mounted at the base of the transformer rather than the top and they come out at an angle to achieve clearance. There are...
So I was laid off in April due to the economy and have been doing a seemingly frivolous job search ever since. I lucked out and actually got an interview with a company and now they are going to make me an offer.
Here's my dilemma: the job is in a small town in central Wisconsin. There's...
My company just had a meeting to discuss purchasing a VFD for a 6000 hp, 1783 rpm, 4160V induction motor. The problem is the motor is too powerful for our process. It is used a booster motor which when the pressure in the system gets above a certain level, we open a recycle valve and cycle...
We just recently test ran a 12,000 hp synchronous motor and I noticed the ammeter read 100 Amps with the motor decoupled and the motor synchronized. Is this normal? I was told this is normal, but to me it seems high even for a motor that size.
Here are the specs I could find on the unit...
I'm a younger engineer who changed jobs fairly recently and moved from the power utility to the petro chemical industry. I was hired in to fill a position that apparently they had a hard time filling and it had been open for several months. When I first started I had several tasks, plenty to...
How does one calculate the magnetic saturation point of an iron stator brushless DC machine? I am am trying to figure out the most efficient winding for an outside runner BLDC motor. Also how can I estimate the no load current at a fixed voltage?
The specs on the Stator are as follows:
OD...
I have a few general questions regarding 3 phase induction motors:
Question 1: We have an 1100 hp induction motor that was originally speced out for 4160 volts. Our supply power is 2300 Volts. The vendor changed the winding somehow to reduce the motor's voltage to 2300 volts. I was not able...
I posted this question in the Power Generating facility forum, but I thought I'd also place it here as this seems to get far more traffic and I have recieved no response from the other forum.
I have been assigned a project for replacement of phase reversal switches at a pumped hydro facility...
I have been assigned a project for replacement of phase reversal switches at a pumped hydro facility in the U.S. Our current set up uses 5 230 kv vertical air break switches on a single operator. The operator is a three position operator which moves approximately 75 degrees in either direction...
I have recently been given the task to design and construct a grounding system for a metal chain link fence at a generating facility. I have never done this before so I'm looking for some help. The fence is 300 feet long and is more or less a straight line. What value should I be targeting...
