Testing Diode on an Alternator 2

[InselR]

Hello,

I am looking for a rotary test equipment that can test an 85 Amps 1600 PIV (DO5) diode at 3500 RPM. We need to apply input voltage and check the output load current slip ring while the diodes are rotating. Added features can be to check forward voltage drop, leakage current, etc.

 

[waross]

Do you have a picture of the machine/
I am familiar with rotating diodes.
I am familiar with slip rings.
Never seen both on the same machine.
I may learn something here.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[wayne440]

+1 for what waross wrote.

 

[InselR]

Did a lot of internet search yesterday and came across a few videos on you tube which are not exactly same but on the same lines -

https://youtu.be/OEGWsps15BQ?si=WIxYkKzh19REXSCw

https://youtu.be/7mn2eADLjsI?si=pMyMzXWgkexhg6DD

https://youtu.be/ubpqt3fr_eE?si=L-uPDSYOV1JuNZcU

https://youtu.be/75PezIznCGk?si=ATT0s4nsCJcNefa9

I am looking for a technologically advanced product which can give output in DC, forward voltage drop. I have also attached the test parameters set by this organisation which wants us to do this.

 

[catserveng]

The only company I know of making a functional online diode monitoring system for salient pole generators is KATO.

https://prod-cd-nidec82.layeronecli...ure/krm2000-wireless-system-9-2017.ashx?la=en

They tend to be very helpful and probably the best resource I know of. Avk had a module but my experience with it was poor, of course that was several years ago and it may have improved, but I think both Avk and Stamford are now owned by Cummins, but another possible resource.

I am also in agreement with comments above, slip rings and diodes (rotating rectifier assembly) is something not usually found on a unit.

MikeL.

 

[catserveng]

Ok, now that I read your attachment (be aware that this is done with caution with all the crap on the internet these days).

Your attachment is a specification for testing a rotating rectifier assembly ONLY, not installed on a final machine. Funny, it VERY similar to an acceptance test document prepared by a former company I worked at to validate vendor supplied replacement rotating rectifier assemblies.

I used to have a picture of a test stand built for that purpose by Kato Engineering and Leroy Somer but can't find it in my archives. Newage Stamford I believe also had a rectifier test stand but I never actually saw it. EM-WEG Group also produced diode assemblies for other manufacturers and may be a possible resource. BTW, that is the ONLY place I ever came across a rotating rectifier assembly used in conjunction with slip rings, since the slip rings were used as part of a simulation for a main field under varying load conditions.

Since it looks like your customer is a possible manufacturer of rectifier assemblies, likely most of the companies I indicated above aren't likely to help a possible competitor.

Hope that helps, MikeL.

 

[catserveng]

Since it seems your customer is an electrical equipment manufacturer in India (I was curious), your best possible resource in this forum is likely Muthu from Edison Company India. To meet the spec you provided you're likely going to have to build a custom test stand.

 

[InselR]

@catserving, Yes the end customer is in India, matter of fact we are also an Indian company, engaged in manufacturing Power Semiconductors for alternators, DC drives, welding machines, cranes, battery chargers, furnaces, APFC panels, etc. (

http://www.rectifierindia.com)

All the rotating rectifiers that we manufacture are small, majorly for 125 KVA but now we want to get into turbines and bigger alternators and that is why the need of this test equipment. Can you please put me across Mr Muthu from Edison. Thank you.

 

[catserveng]

Muthu is here on the forum, surprised he hasn't chimed in yet. I believe he would have the expertise and ability to help you develop a test stand based on your needs.

His website,

https://www.edison.co.in/

Good luck in your venture,

MikeL.

 

[Gr8blu]

Posted this response to the OPs other thread.
Note: Did this a few times over the years for different OEMs. Usually running up to overspeed ONCE was not enough - we were looking for the cyclical fatigue on the components from multiple speed excursions.

The general method is to bench test the component(s) (i.e. test when not rotating) - diodes, thyristors, etc. prior to attachment onto the moving assembly. Once installed and (correctly) wired up, the capability of the individual component is verified by having the rotating assembly operate as required - under all design points.

Note that design points may be a combination of any or all the following: speed, current, voltage, vibration, humidity, and/or temperature. In some cases it may also involve the chemistry of the surrounding medium (e.g. air).

A number of OEMs that do this kind of thing use a dedicated test stand (mandrel to hold the assembly, and an electric motor to drive it at the desired speed) and some mechanical contacts (brush to collector ring, for example) to extract the relevant electrical performance.

Converting energy to motion for more than half a century

 

[edison123]

Thanks, Mike.

@OP

As OEM, you must have tested your rotating diodes for operating conditions, surely?

I have used your DS2001SD40 model diodes for an 11 KV, 30 MW, 3000 RPM TG alternator brushless exciter rated for 155 KW, 250 V, 600 A, and they are working fine for the past one year. Hit me up for any performance feedback (but I doubt BHEL would buy it since we compete with them.)

2 pole machines are beasts because of high centrifugal forces and resultant fatigue failures. The entire RRA must be tested for speeds up to 4000 RPM, including 20% overspeed for 3600 RPM machines. You could rig a test bench (if you don't have such a setup already) for your RRA which could involve a variable speed motor up to 4000 RPM, a variable 3 phase input source, a resistor load bank, sliprings etc.

Muthu

http://www.edison.co.in

 

[InselR]

@edison123 Can you please forward your contact details, would talk you about this.