Interesting Wind Generator. (wind As In Weather)

Hi all. Came across a wind (winding around the corner) last week, and I’m not sure if I understand it’s purpose.

A wind generator - permanent magnet rotor 36 slot with not 18, but 36 groups of individual coils. Had a quick look at it and figured it was a 6 pole straight series connected with an internal star which I scooped out at a glance. Went to chop it out and spotted some extra connections which didn’t make sense (as it was machine wound with no obvious crossovers). To discover that it had 12 groups per phase layered on top of one another and series connected 720 deg around the stator. With less turns in inner slots and more in outer. Thought at first (because it was basket wound) that they were taking advantage of varied inductance in slots, ..but that didn’t make sense as you would get the same effect if it was lap wound. Anyway asked the boss and he couldn’t give me an answer, so I’m guessing that the extra 360 of the same phase is creating a slight lag in the induced emf causing a smoother output to the internal three phase bridge rectifier so that the charging unit receives a smoother DC..pheww

Anybody seen one of these before? And am I correct?. If I am correct then would there be advantages to winding a three phase motor this way, wouldn’t it be much smoother and work better with a VSD.

Have included a rather bad diagram of one phase to give you an idea of what I’m trying to explain.

Brake Pad Mechanism

Hi All.

Interesting problem here.

Sparky serviced a brake mechanism that was chattering and decided to file and polish face of laminations (surrounding coil) to make for good contact (shading rings in place ok)... It worked, only In doing so there are major eddies on the pole faces leaving a huge residual magnetism and causing the laminations to stick together after coil is de-energized.. I'm assuming (even though there is a very strong tension spring pulling them apart again) . It’s going to take hours even a day to separate and re-varnish every lamination and is therefore not really worth doing logistically. Is there another way anybody can think of to dissipate residual from pole faces/laminations after supply is broken?.

Our only other idea is to skim faces to hope for a difference!

Onboard Stirling Engine Generator

I wonder if you could use a stirling engine as the prime mover for an onboard generator to supply an ev motor. Why am I thinking this? ..Well simply to get rid of the serious weight and cost involved in a battery bank and because stirling engines are a very efficient engine opposed to combustion type! There are probably many holes in this idea, but I thought I would throw it out there as a topic starter and there has to be a better/cheaper way than fuel cels and battery storage!.

Industry Standard Discrepancies

I have issues with the EWRB and their exams full of wrong answers expected, based on false information taught.

There have been gaps and misunderstandings in my knowledge due to personal confusion between what is “in the books” and what I see in reality!.

ie: If you are ever asked to sketch a single phase cap start motor, you must have the centrifugal switch on the supply side of start winding. I guess the reason being is that little potential voltage will exist between earth and run and the start winding. Makes sense yes!

In reality having disassembled, reverse engineered , wound and fixed hundreds of 1phase motors, I have seen ONE wired like this. The common is ALWAYS on the phase the C/S and cap are ALWAYS on neutral return after start winding.

If they teach it. Why don’t they regulate it?

Another example

They always refer to thirmisters as though they where microtherms. There is a HUGE difference. A Microtherm is a small bi-metal device that will operate to open the circuit when a certain temperature is met due to over current over a length of time. Microtherms are in series with the motor windings.

Thirmisters (at least the ones I know of) normally come as three small silicon devices (one for each phase) that act in a similar function as a PT100 . They have a temperature co-efficient and are not designed to physically disconnect the supply …only as a transducer as such. Try and wire them up in series with the windings and your in a whole lot of trouble.

If I draw a single phase motor the way they are manufactured and distributed to the world (including NZ), I get ZERO marks.

If I use the word Microtherm instead of thirmister, I get ZERO marks.

This is only two examples, I have many more.

Have I unnecessarily complicated things again?, or maybe I am incorrect? Does anybody have anything to say about this?

Clayts

Extra Exciter On Generator

A quick question.

Worked on a Generator today. Was full of oil, basically electrosoled, dryed, megged, reassembled and loaded up/output checked. All OK.

Why did it have an extra permanent magnet exciter externally?

Asked boss, he told me it acts as a sort of tacho and will give a constant voltage dependant of speed and can be used as a benchmark of types for the AVR and something to do with it retaining it's residual magnetism (being permanent magnet). Didn't really get what he was saying.

Asked marine electrician. He told me that it is more suited for inductive loads!!

Could somebody give me an actual answer, that makes sense?

Clayton