HV plate transformer
IamSmooth, Thu Jan 04 2007, 05:08AMI just got a High voltage plate transformer used for setting up the potential on the plate of a high voltage vacuum tube. It is rated to go about 1300v. I powered it up slowly with a variac while monitoring the current draw on the primary and the current and voltage on the secondary under various loads. It looks like it behaves like a MOT and I don't see any current limiting. The input current keeps going higher as I increase the variac.
I want to be safe when designing a transmission tube tester. I was planning to put a fast-blow fuse on the primary rated at a little more than the current I expect to draw. I want to protect the system from a shorted tube being inserted at the HV end. Any comments or suggestions from anyone?
Re: HV plate transformer
Sulaiman, Thu Jan 04 2007, 10:50AM
Assuming VARIAC - TRANSFORMER - RECTIFIER(S) - CAPACITOR as the setup;
My first choice would be a miniature circuit breaker (MCB) between Variac and Transformer.
A fast-blow fuse would be ok if you always 'wind up' the voltage from zero each test
A sudden application of full ac voltage to the transformer
would cause a large 'inrush current' that would blow the fuse.
A slow-blow fuse would be ok but not as convenient as an MCB.
my 2cents worth
Sulaiman, Thu Jan 04 2007, 10:50AM
Assuming VARIAC - TRANSFORMER - RECTIFIER(S) - CAPACITOR as the setup;
My first choice would be a miniature circuit breaker (MCB) between Variac and Transformer.
A fast-blow fuse would be ok if you always 'wind up' the voltage from zero each test
A sudden application of full ac voltage to the transformer
would cause a large 'inrush current' that would blow the fuse.
A slow-blow fuse would be ok but not as convenient as an MCB.
my 2cents worth
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