Constant Voltage Transformer (CVT)
n short, CVTs are basically 1:1 transformers that are excited high on their saturation curves, thereby providing an output voltage that is not significantly affected by input voltage variations. This special characteristic is the foundation of the application of ferroresonant transformers as power conditioners.
Product Description
The portion of the magnetic core over which the secondary winding is wound is saturated,
while the portion over which the primary is wound is not saturated. A capacitor is
connected across the secondary winding to tune out the output at a fre¬quency very close
to 50 Hz.
This capacitor also makes the current in the secondary winding to increase which helps
in the saturation of the secondary flux. Since the secondary ac flux is restricted to a
saturated value for a large range of the input voltage (170-270 V), a constant voltage
is available across the secondary winding. The output voltage will not be of a pure
sinusoidal waveform but will be an approximate sinewave with the peaks flat¬tened
approaching a square wave. The output voltage waveform of a CVT is shown in the figure.
In the figure, a compensating winding is shown connected in series to the secondary to
improve the CVT performance.
| INPUT VOLTAGE | 180 V - 260 V |
| OUTPUT VOLTAGE | 220 V - (+/-)1% |
| LINE FREQUENCY | 50 Hz - (+/-)5% |
| EFFICIENCY | Above 90% |
| OUTPUT REGULATION | 1% at no load to full load |
| OUTPUT WAVE FORM | Sinusoidal |
| WAVEFORM DISTORTION | 5% (approx. under full load) |
| LOAD FACTOR | 0.75% lag to 0.9% lead |
| AMBIENT TEMPERATURE | -5- C to 50- C |
| STANDARD KVA RATINGS | 500 VA TO 5000 VA |
- Electronic equipment's
- Telecom equipment's
- Electronic type writer
- Bio medical equipment's
- Micro / mini computer
- EPABX
- TV / DVD recorder and player
- CNC system
- X-ray machine
- No moving parts used, hence very high reliability
- Faster voltage correction almost instantaneous
- Intrinsic current limiting and short circuit protection
- Short term over load capability
- Very high line transient/spike rejection capability and excellent input to output isolation characteristics
Frequently Asked Questions
The very best power protection comes from a special type of transformer known as
a Constant Voltage Transformer (CVT). Providing unparalleled reliability and
conditioning performance, spikes, and electrical noise are neutralized with
attenuation as high as 75dB.
In addition, the input (or primary) and output (or secondary) transformer
windings are physically separated. Known as Galvanic isolation this separation
ensures that there is no direct connection between the mains supply and load.
A CVT, therefore, provides an impenetrable barrier to spikes and high-frequency
electrical noise. This barrier also works in reverse mode to prevent a 'noisy'
load from polluting the mains supply itself.
- It does not have any moving parts or semiconductor and hence highly dependable.
- Input control is not used
- Comes with output amendment within ½ cycle for specific load
- Competent overburden for short term
- Output costing
- Spike dismissal or overdrive line transient
- Space saving design
- Quick installation
- Easy transportation
- Superior efficiency
- Low maintenance hassles
- Good voltage control and power regulation
- It offers better voltage regulation despite the variation in voltage regulation from 1 to 4%.
- It can be customized to meet the constant current output Vs. the voltage supplied to normal devices.
- Controlling the current is the major advantage of CVT
- It is highly durable and does not come with any moving part facilitating easy maintenance allowing them to work longer hours without any sags.
- It can regulate the output voltage of up to 60% for a particular period during voltage drop. Though, it does not offer good resistance when there is temporary voltage interruption or during very intense voltage drops.
- CVT is preferred over sag-mitigation gadgets as it is maintenance free and there is no need for batteries to run the device
- It comes with special features and with tank circuit design. It is a combination of an inverter and UPS application. Moreover, it offers uninterrupted transfer to a secondary source.
- In case of an overload or fault it comes in handy. Even during complete inverter failure, it helps to maintain the power load.
- It helps to supply constant current output instead of constant voltage.
- Current limiting is an inlaid benefit in Ferro resonant transformer
- During load current going over 150% of the rated region, there is a collapse in the output voltage in a limited value thereby limiting the current.
- There are no surges, noise, or harmonics occurring during the circuit design
- It is long-lasting and sturdy and comes with warranties touching 10 years too
At full load and ideal conditions, its efficiency can reach up to only 93% and substantially drops at light load. Meaning, that as the Ferro resonant transformer's loading decreases, its efficiency also reduces significantly. Typically, at half load, CVT efficiency ranges from 75% to 85% only as compared to a regular transformer that has an efficiency of more than 95% for the same loading percentage. humming audible sound and relatively high cost
- The efficiency of a Ferro – resonance transformer is lower than a conventional transformer.
- The efficiency of CVT is approximately 93% for its full load range and it decreases as the load decreases.
- The efficiency of CVT at half load lies in the range of 75% to 85% whereas the efficiency of the power transformer is approximately above 95% for that load.
- The design of CVT is done by considering overload or inrush current.
- When the size of CVT increases 2 to 3 times for rated current, its efficiency drastically reduces and it also produces a humming sound.
- It is highly reliable and comes with zero moving parts
- Feedback control is not used
- Comes with short circuit protection
- Restricted inbuilt current
- Protection from line loss
- Short term overcharge capacity
- Prominent input voltage
- Highly isolation between input and output
- Quick corrections
- Low maintenance cost
- Quick voltage regulation
It has a unique configuration that offers isolation from load equipment. Moreover, the device is free from surges and line noise. The product is highly reliable and long-lasting supported by warranties. There is a huge demand for CVT in the market and the device can be customized to meet the client's needs.
- In the CVT the primary and secondary windings are separated with a broad air gap impacted by a magnetic field. This results in a striking decrease in capacitive and inductive loadings. Regular power transients are taken care of by this exclusive design.
- In between the output voltage and the input voltage there exist phase difference giving rise to superior output sound reduction.
- The windings in a CVT are isolated the noise is cut off from the high-frequency module.
- Ferro resonance is a phenomenon in the CVT that keeps the balance from any type of variation that occurs in the AC voltage. In this case, the secondary output inductor forces to vibrate making use of a greater degree of capacitor performance giving rise to this occurrence.
- The features stated above indicate that CVT is unique and superior to other types of voltage stabilizers and SMPSs. The CVT allows consistent power output saving the appliances during a power surge.