Which is better, a CVT or an Isolation transformer ?

Question

For the protection of a telephone exchange, from voltage transient, spikes etc, which is more useful and applicable, an Isolation transformer or a constant voltage transformer (C.V.T.) ?

Answer 1

A CVT is more sophisticated than a isolation transformer. An isolation transformer helps to protect the devices, but a CVT will "buck or boost" line voltages to maintain a more stable and filtered voltage.

Answer 2

neither is designed to handle transients and spikes. the isolation transformer allows the plant ground to be isolated from the electrical ground, which is not necessarily a good idea, unless powerline buzz is excessive in the audio lines. it is just a 1:1 transformer and as such passes on the wave form of the incoming power line, complete with glitches and such, with a small degree of bandwidth reduction. A CVT is a ferro-resonate device which helps smooth out powerline rms voltage fluctuations by changing the waveform of the incoming voltage from a pure sinewave. it also will pass short term glitches and spikes, sometimes emphasizing them by expanding their duration period by changing a one-cycle event to a ringing overload. The best surpressors are made from "transorb" type elements and are available in standard commercial packages that attach to the incoming service connection. you will need a good ground for maximum effectiveness. if the transorb fires it will pop its accompanying fuse, so regular maintenance is mandatory for continued protection.

Answer 3

I was about to answer this question, but I saw Lare's answer.
Good answer.