There are times when one feels that a stabilizer is not enough. After all, a stabilizer can correct voltage with a certain finite speed. We would think that our instruments are connected to a stabilizer and are unaware of the fact that it is stilt passing on the spikes, voltage surges, glitches, noise etc. Which are so short, that it cannot be corrected by a stabilizer.

What then? The answer is a C.V.T. from ALTIME This works on magnetic saturation principle, resonating with a tank circuit of high Q factor. When incoming Mains voltage is low the capacitor provides the necessary additional gain in power, keeping the output voltage steady. On the other hand , when the mains voltage is high the leakage reactance drops the difference of voltage. This correction of voltage is instantaneous even for sudden dips and spikes.

Ferroresonant transformers are a special type of laminated transformer which provides a regulated output. These are sometimes known simply as "ferros", or "CVTs" (constant voltage transformers). Using a special magnetic structure and a capacitor, ferroresonant transformers can supply a well regulated output voltage which remains constant despite changes in input voltage and load.

In some specialized applications, these devices can be designed to supply a constant current output, rather than constant voltage. Current limiting is an inherent benefit of ferroresonant transformers. If an overload, or even a short circuit is applied, secondary current is limited to a safe level and primary current is actually lower than at normal full load. Another inherent benefit is that the ferro serves as a low-pass filter, supplying to load with power, but effectively removing transient and surge voltages. Energy stored in the transformer structure even allows the output to "ride through" brief input power interruptions.

For dc (rectified output) applications, ferros supply a quasi-square wave output which can reduce or even eliminate the need for filtering. For ac load applications, ferros can be designed to supply a high quality, low distortion sine wave output. Ferroresonant transformers are single phase devices, but combinations of two or three ferros can provide all of the ferros' advantages in three phase applications

Ferros which rely upon only their rugged copper and steel structure for regulation can easily maintain a desired output voltage within 3% despite wide variation in input voltage and/or load. Another variant, known as the controlled ferro, adds electronic control and can provide an adjustable output with regulation to better than 1%.