Hi Rolv,
Technically these had a "C" after the numeral designation too like EPC-450C etc. but a minor quibble.
There is at least one other and that is an EPC-450C-II which is the one I have. This cartridge is constructed just like the 451C whereas the original 450C is different and uses a different stylus.
The EPC-450C-II stylus (clear body) and the EPC-451C stylus (red body) are interchangeable and, in fact, I currently have a 451C stylus on my 450C-II. I don't know if there is any performance difference between the two.
I guess I can't speak to the other models because I haven't heard them but my 450C-II works very well for CD-4. Lots of detail. All of these were, of course designed specifically for CD-4 and the semiconductor feature was Panasonics big thing back then.
These cartridges require a DC voltage to operate, of course, and this is supplied by the preamp or demodulator through the same wires as the signals from the cartridge so there are no extra connections.
The two best known demodulators that feature a semiconductor selection are the Panasonic SE-405 and the Technics SH-400.
If you try to use a semiconductor cartridge with a standard demodulator without a MM - SC switch, there will be absolutely no signal from the cartridge.
Doug