Transformers come in all shapes and sizes, and there are many different types of transformers that suit different needs. Transformers can be custom designed by professionals to meet the customers’ needs and requirements specified or purchased from among the stock.
Buying a transformer can be a little daunting if you do not know what you are looking for because transformers can come with several different specifications, including design, requirements for installation etc.
This page provides direction for people interested in submitting their transformer requirements. The following list describes each specification our engineers will request.
There are some key features of the transformers that need to be considered before purchasing the transformers. The following are some of the essential electrical parameters:
Input Voltage
Input Voltage is the amount of voltage applied to the terminals of the primary winding of the transformer. If this is the voltage coming from your wall power outlet, it would likely be 110-120 volts (for North America) or 220-240 volts (for much of the rest of the world). North American industrial applications often use 220, 240, or 277 volts.
Input Frequency
Input Frequency is the frequency of the voltage applied to the terminals of the transformer’s primary winding. If your input power comes from your wall outlet, the likely input frequency would be 50 Hz (in India/Europe) or 60 Hz (North America).
Output Voltage
Output Voltage is the amount of voltage supplied by the transformer to the applied equipment. The equipment to be powered by the transformer will typically require a specific voltage and current for proper operation.
Output Current
Output Current is the amount of amperage supplied by the transformer to the applied equipment. The output current (along with the output voltage) determines the output power.
Output Power (often referred to as “VA”)
Output Power is the output voltage multiplied by the output current. It is the main determining factor for the transformer’s physical size (the more significant the output power, the larger the physical size—for similar construction types).
Because the voltage and current of the secondary circuit may not be in phase, the actual power delivered to the load may be lower than the VA (apparent power) rating.
Physical Size Requirements
As you would expect, there is a limit to how small a manufacturer can build a transformer for a required output voltage and current. However, different configurations may allow manufacturers to change the shape of the transformer so it might fit the available space or enclosure.
Estimated Annual Usage
This information is good to know because it helps us determine material and price. As you would expect, the cost-per-transformer is likely to decrease with a higher annual usage amount.
Mounting Method
The mounting method is the preferred way the transformer will be attached to the equipment, and there are three standard methods:
Chasis Mount
The transformer frame is mounted directly to the equipment, either by its frame or an attached bracket.
PCB Surface Mount
The transformer is mounted on a printed circuit board with pads (or feet) that are soldered directly to the board’s surface.
PCB Through-hole Mount
The transformer is mounted on a printed circuit board with soldered pins that protrude through the board.
Termination Type
Termination type is the preferred way the input and output windings will be terminated. The equipment to be powered by the transformer may also require a specific type of termination. Shreejee Electronics commonly configure the following termination types:
Wire Leads
Input and output lead wires are cut and stripped to desired lengths
Quick Connects
The transformer has tinned-brass tabs of the desired size that are designed for quick connection/disconnection.
Terminal Board
The transformer has tinned-brass tabs of the desired size that are designed for quick connection/disconnection.
Inline Connectors
The transformer leads are crimped to connectors inside plastic housings, which then fit mating connectors on the applied equipment.
Bolt Terminals
The transformer has individual brass or stainless-steel bolts (usually 10-32 or ¼-20 size), one for each input and output lead. Bolt terminals are often the preferred termination method for power transformers over 2 KVA.
Solder Lugs
The transformer has tinned-brass tabs with holes to fit your specified wire size for easy soldering connections.
Screw Terminals
The transformer has individual screw-connects, one for each input and output lead. Different types of terminals, such as finger-safe terminals (shown on the right), meet European standards.
Other Requirements
Copper Shielding Band
Some applications may require unique features, such as a Copper Shielding Band (as shown), to reduce transformer noise.
RoHS Compliance
RoHS compliance helps keep all listed hazardous substances out of the marketplace and restrict their use in production facilities.
As you may expect, our design engineers gather a standard set of information when taking transformer requirements. If you are unable to locate any of this information, we may help fill in the blanks. You’re always welcome to call in your specifications or send them to us through the Quote Request page.
