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Don't Forget to Change Your Backup Batteries !

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awemawson:
Unlike mosfets thyristors once triggered continue to conduct until either the power source is removed or they are capactively forced into non conduction by a negative pulse. (Comutated)

AdeV:

--- Quote from: awemawson on July 16, 2020, 02:31:56 AM ---Unlike mosfets thyristors once triggered continue to conduct until either the power source is removed or they are capactively forced into non conduction by a negative pulse. (Comutated)

--- End quote ---

I've been googling :) In fact, Thyristors are hardly like MOSFET at all..... but hey ho.

Having search, in vain, for any kind of documentation on my Contraves motor, the best I can do is a bad picture of a ratings plate on one on eBay, which doesn't tell me (for sure) that this is a DC motor, although I'm pretty damn sure it is, there are only 2 high current wires leaving the thyristor board (3 phase wires coming in). The motor is rated 400V and 20amps, which seems to be well within the capabilities of a MOSFET.

I'm going to have a chat with my friend the electronics genius ( :bow: I don't use that word lightly), if I'm lucky he'll offer to design a board for me  :beer:

awemawson:
I seem to remember that the only complication is profiling the field current value against rotor speed - iirc the current has to decrease as the speed increases which is counter intuitive.

Attached is the original test sheet for my Mawdsley DC motor when it left the factory. It's much the same order of magnitude as yours, and the test results show rotor and field current versus speed - might be useful as a starting point :scratch:

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