There are three ways to reduce transformer temperature rise. The first is to lower the maximum flux increment (Bm) of the transformer core, because core losses (hysteresis loss and eddy current loss) are proportional to the square of the flux density. The second is to lower the switching frequency of the power supply, because core losses are proportional to the operating frequency. The third is to reduce winding losses: winding loss (mainly eddy current loss) and skin effect loss are also proportional to operating frequency, and to reduce DC loss in the winding the current density of the conductor must be lowered - the current density of enamelled wire generally should not exceed 4.5A/mm².

1. Overview of voltages around the world

Mains voltages used indoors around the world fall broadly into two groups: 100V~130V and 220~240V. The 100V and 110~130V range is classified as low voltage, used in the United States, Japan and on ships, where safety is the priority. The 220~240V range is called high voltage and includes China's 220V, the UK's 230V and many European countries, where efficiency is the priority. Some countries that use 220~230V, such as Sweden and Russia, also employ 110~130V in certain cases.

100V: 2 countries - Japan, South Korea

110~130V: about 30 countries and regions - Taiwan (China), United States, Canada, Mexico, Panama, Cuba, Lebanon, etc.

220~230V: about 120 countries - China, Hong Kong (China, 200V), United Kingdom, Germany, France, Italy, Australia, India, Singapore, Thailand, Netherlands, Spain, Greece, Austria, Philippines, Norway, etc.

2. Travel plug adapters

Chinese standard plug: used in China, Australia, New Zealand and Argentina; characterized by three flat pins.

US standard plug: used in the United States, Canada, Japan, Brazil, the Philippines, Thailand and Taiwan (China); characterized by one round pin and two flat pins.

UK standard plug: used in Hong Kong (China), the United Kingdom, India, Pakistan, Singapore, Malaysia, Vietnam, Indonesia, the Maldives, Qatar and other countries and regions; characterized by three rectangular pins.

European (German) standard plug: used in Germany, France, the Netherlands, Denmark, Finland, Norway, Poland, Portugal, Austria, Belgium, Hungary, Spain, Sweden and other EU countries, as well as South Korea and Russia; characterized by two round pins.

South African standard plug: mainly used in South Africa, India and Russia; characterized by three round pins. There are also Italian standard and Swiss standard plugs, among others.

Travel plug adapters also face the situation where a single country or region uses multiple standards.

By Usage

Travel charger: short for travel mobile phone charger, a lightweight charger suitable for use while travelling, including in other countries. Its input rating should therefore be 100-240V, 50-60Hz. Fast charging, however, only works at a specific voltage.

Car charger: short for vehicle charger, used inside a car. One end plugs into the cigarette lighter socket and the other connects directly to the device to be charged. Note the voltage it can use: the standard input from small vehicles is 12V. Generally, charger manufacturers test in the 9-15V range during development. Some large vehicles provide 24V, and our chargers are tested up to 28V. When using a low-voltage car charger, do not use it on 24V vehicles, otherwise the internal components may be damaged.

Desktop charger: a relatively bulky phone charger, often with LED or LCD indication, and divided into single-slot (for a phone or a battery pack only) and dual-slot types (suitable for home or office).

By Battery Type

1. NiMH / NiCd battery charger, calculated at 1.5V per cell

2. Lithium battery charger, calculated at 4.25V per cell.

3. Lead-acid battery charger, calculated at 6.9V-7.3V per cell. Lead-acid batteries come with and without float charging. A three-stage float charger has a no-load voltage of 6.9V and a maximum charging voltage of 7.3V, while a charger without float has a no-load voltage of 7.3V.