harmonics testing using fluke 434

[ArchieMedes]

Hi to all,

I am currently measuring the harmonics on a panel (just voltage harmonics) and is using fluke 434 as the measuring tool. I measured from the output of a thyristor a harmonics of above 15% but varying. I wonder if this is correct. I would like to ask how to correctly set the settings parameters on the fluke 434 to give an accurate harmonics reading.
I had already set the type of connection which is 3ph delta IT but there are still some other parameters in the setup func. preference in the setup menu which may be giving incorrect reading like offset,span,etc.

 

[ron]

The users manual is pretty big http://assets.fluke.com/manuals/434_435_umeng0300.pdf

Did you call tech support?

 

[Besoeker]

Hi to all,

I am currently measuring the harmonics on a panel (just voltage harmonics) and is using fluke 434 as the measuring tool. I measured from the output of a thyristor a harmonics of above 15% but varying.

Thyristor......are you a Brit?
What configuration of thyristor circuit was it?

 

[ArchieMedes]

Thanks Ron

Besoeker, the thyristor (or SCR to you) is on a back to back configuration. 3 SCR was used to control the 3 phase delta load.

 

[Besoeker]

Thanks Ron

Besoeker, the thyristor (or SCR to you)

No, it's thyristor for me also......

is on a back to back configuration. 3 SCR was used to control the 3 phase delta load.

Three back to back thyristor pairs? W3C configuration.

Do they operate in phase control mode or burst fire mode?
If phase control, then 15% distortion is certainly possible.

 

[ArchieMedes]

No, it's thyristor for me also......


Three back to back thyristor pairs? W3C configuration.

Do they operate in phase control mode or burst fire mode?
If phase control, then 15% distortion is certainly possible.

Actually only 2 back to back thyristor pairs (2 leg control) with delta IT load. It is not phase control, it is burst fire mode. Not sure why it has high harmonics distortion. That's why maybe the measuring equipment or procedure problem.

 

[Besoeker]

Actually only 2 back to back thyristor pairs (2 leg control) with delta IT load. It is not phase control, it is burst fire mode. Not sure why it has high harmonics distortion. That's why maybe the measuring equipment or procedure problem.

I know the arrangement. In the last few months we built and shipped six such systems, mostly around the 250A mark.
I also don't know why you are measuring harmonics. I suppose you could be getting sub-harmonics related the the frequency of the bursts. It isn't something I've measured.

As a matter of interest, do you know the manufacturer of the equipment is?

 

[GeorgeB]

... the thyristor (or SCR to you) ...

interesting, and I'm showing my age... My old (USA published) 1969 RCA "Transistor, Thyristor, and Diode Manual" uses, as I still do, thyristor as the "parent" with triac, SCR, and diac as specific device types ... what is the current (if country dependent, I'm curious) correct and accepted terminology?

 

[Besoeker]

interesting, and I'm showing my age... My old (USA published) 1969 RCA "Transistor, Thyristor, and Diode Manual" uses, as I still do, thyristor as the "parent" with triac, SCR, and diac as specific device types ... what is the current (if country dependent, I'm curious) correct and accepted terminology?

Interesting question.
From Wikipedia:
"It is from a combination of "thyratron" and "transistor" that the term "thyristor" is derived."
In UK, I've known them as thyristors for most of my professional life.
And as SCRs. I'm not sure which was first for me.
But the common usage here is thyristor.

 

[Besoeker]

To add to the above, I did have some involvement with thyratrons on one early project.
They were configured as phase controlled rectifiers for adjusting the field excitation on DC motors on a paper machine. The armature supply was from a Ward-Leonard system.
We upgraded that in several iterations.
The thyratrons were replaced with thyristors and new circuitry.
The Ward-Leonard was replaced with a solid state (thyristor) DC supply.
Then the whole lot was changed for individual DC drives. We also put in a new SCADA system.

Like much of UK industry, the paper mill closed down a good many years ago but those projects and that particular mill sticks in my mind for a whole number of different reasons.

 

[gar]

120225-2146 EST

My earliest SCR manual is titled "Controlled Rectifier Manual, by GE, copyright 1960. Has no edition number. Internally SCR is used.

The second edition is called "SCR Manual", copyright 1961.

A Westinghouse manual is called "SCR Designer Handbook", First Edition, 1963.

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