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(1018 products available)
The variable voltage transformer three-phase types listed are all of the electromechanical type. These types provide variable voltage from fixed voltage. The main difference is how they achieve variable voltage.
Tap changing transformers
These transformers obtain different voltages by using tap points on the primary or secondary sides. Some use on-load tap changing, where taps are changed under load using special switches. Others use off-load tap changing, where voltage change requires transformer de-energizing.
Auto transformers
Auto transformers are the same as tap transformers, except that they have an internal winding that is self-connected. With this connection, only a portion of the transformer acts as a separate primary and secondary winding. This design makes auto transformers compact and lighter with lower costs.
Rotary convertersThe rotary converter voltage variator 3 phase provides AC from a different DC supply. This is done by electromagnetically generating the three-phase AC waveforms using DC power and a rotating magnetic field. They are used where AC supplies had to be obtained from a DC source.
Electronic control transformers
The electronic control transformer variators are new technology electronic devices. They use semiconductor power electronics to achieve automatic voltage regulation through microprocessor controls, pulse width modulation, and other electronic techniques. They are smaller, lighter, cheaper, noise-free, pollution-free, and more techno-logically advanced than mechanical types.
The selection of variable voltage transformers for buyers should be based on various voltage regulation requirements and transformer limitations to accomplish the desired objective effectively.
Load voltage
Consider the voltage the load needs to operate at nominally. The transformer secondary has to be rated for this voltage. If the load needs a lower voltage, a buck configuration should be used. For higher voltages, use an appropriate boost configuration.
Transformer power rating
Variable voltage transformers come with different power ratings. This ranges from small watts to kilowatts and even megawatts for industrial ones. Select a transformer rated sufficiently above buyer load power to ensure constant voltage output without overheating.
Output power frequency
The output frequency is the same as the supply frequency because buyer transformers are mains frequency products. This is usually 50 Hz or 60 Hz depending on the country. Special designs can cope with different frequencies.
Output voltage range
This is the range of the output voltages. It should vary between the minimum and maximum values but include buyer voltage. Only rotating types can provide continuous adjustment. Electronic types offer fine regulation but are also electronic noise sensitive.
Transformer construction
Users should note that some designs are enclosed, while others are open. Take care of the environmental conditions where the transformer will be installed. Enclosed types are needed in hostile dusty or humid environments. The open type is for clean space environments.
The variable transformer has several practical load connections. How the load is connected depends on whether the load is designed to operate at a fixed voltage or if it requires the flexibility of voltage adjustment.
Fixed connection
If the load is a standard appliance expected to work at a fixed voltage, connect it through the fixed output terminal. This fixed output terminal connection is needed only for low-power appliances, where voltage variation is not required.
Manual adjustment connection
Higher power appliances should have their voltage level adjusted by manual methods prior to connecting. This means connecting the appliance to the manual output terminal and using the manual rotary voltage selector to set the required voltage before switching on the appliance.
Automatic connection
For appliances that need continuous voltage adjustment, the voltage can be automatically set by connecting the appliance through the automatic output terminal. The automatic voltage regulator will adjust the output voltage as the input voltage changes to keep the output voltage constant.
Three-phase variable transformers are used in kinds of electrical equipment and motors. They can be replaced in these types of machines when the primary need arises.
Identifying replacement transformer
Look for the ID plate on the transformer. This will give the manufacturer, standard, and typical frequency, rated power in VA or kVA, and output voltages. All these are to be looked at and compared against the desired requirements.
Turn off power
As is the case with every electrical device, before starting the replacement job, switch off the electric supply to avoid electric shocks, short circuits, or damage to equipment.
Remove old transformer
Carefully detach any electrical connections, such as wires or cables, from the old transformer. Unscrew it from its mounting and take it out. Be careful not to damage surrounding equipment or components.
Install new transformer
Place the new variable voltage transformer in the position it occupied before. Securely fasten it to its mounting and connect the electrical wiring to the appropriate terminals or input/output connections on the new device.
Re-energize system
After the new transformer has been successfully installed, restore power and cautiously check that the new transformer functions properly and that the system operates as intended. Be careful of output voltages because they may be fatal.
Voltage regulation
This automatic voltage regulation maintains the desired output voltage even with input variations. This ensures stable voltage levels when loads fluctuate or with AC mains disturbances.
Overload protection
Many models have built-in electronic overload protection. This disconnects the output when overload conditions occur. This prevents damage to the transformer and connected equipment from overcurrent situations.
Waveform improvement
This is due to reduced output harmonics. Some three-phase types for sensitive equipment decrease the output voltage waveform distortion percentage. This helps improve equipment performance and increase operating safety.
Isolation function
The isolation function of the input and output improves electrical safety. It protects against surges and interference. This helps protect connected load equipment from faults on the primary side.
Surge suppression
Many regulated types incorporate surge protection circuits internally. This protects load equipment from voltage spikes and transients coming through from the mains supply that can otherwise damage appliances.
Flexibility and convenience
Transformers allow easy output voltage adjustment and manual and automatic selection. This conveniently adapts a single transformer to different load voltage requirements without needing additional equipment.
Yes, a Variable Voltage Transformer can be connected to an electric motor, but users should ensure the output voltage of the transformer matches the rated voltage of the motor. This means the transformer voltage should be the same as the required voltage for the operational motor.
A variable voltage transformer can be used with a battery charger. A battery charger requires a DC voltage supply to charge a battery system. A variable transformer will reduce the AC main voltage to provide the DC voltage needed by the charger.
A standard transformer does not allow voltage adjustment. It simply steps up or steps down voltage levels between supply and load fixedly. A variable voltage transformer allows continuous output voltage adjustment. This enables flexibility for various load voltage requirements.
Users should always follow safety precautions like grounding the transformer properly, avoiding wet hands or surfaces when handling electrical equipment, and not touching live wires/terminals. Additionally, using circuit breakers or fuses for overcurrent protection is highly recommended.
