All you need to know about voltage transformers:
What is a transformer?
A transformer transfers electrical energy from one circuit to another through the transformer’s coils, designed to step up (increase) or step down (decrease) AC voltages. A transformer normally consists of two wire wrapped coils, usually known as primary and secondary windings. Energy is transferred from the primary to the secondary through mutual induction caused by changing electromagnetic fields. The primary coil is the input coil (or power source) and the secondary coil is the output coil (or load). If the coils have a difference number of turns around the core, the voltage induced in the secondary coil will be different to the first.
Types of Transformers
The two major types of transformer are laminated cores and toroidals. Traditional laminated transformers have laminated covers and are cube-shaped transformers. Toroidal mains transformers are wound on an iron ring (Torus) and are becoming more widely used due to improved modern winding techniques.
Construction of Transformers - Traditional & Toroidal
Features of the Toridal Range:
• Moulded plastic enclosure to produce an attractive product for the home.
• Double locking safety feature of the enclosure to prevent damage following misuse.
• Full Encapsulation of the Transformer -
a) Improves heat dissipation
b) Prevents ingress of moisture, etc.
• Toroidal Construction -
a) Improves heat dissipation
b) Prevents ingress of moisture, etc.
c) Improved external magnetic field
d) Smaller size
e) Reduced weight
Why are transformers used?
Transformers are needed as different countries around the world have different voltages. Countries in the North American, parts of Central and South America, the Caribbean and in parts of the Pacific operate on 110 volt / 60Hz, while the rest of the world operates on 220 volt / 50Hz. In general the 100Volt includes the voltage range of 100-125V and 200Volt includes 220-250V. Some countries operate on both 110V and 220V.
Additionally to the voltage differences around the world, there are also two other major differences – the next being the frequency and the third is the plug adaptors (Learn more in the Article – World Power).
If you are travelling abroad with UK products or are buying products from abroad then it is likely that you will need a transformer. If you have purchased appliances from abroad to use in the UK that require 110 Volts you will need a Step Down Transformer. If you are using UK equipment (240 Volt) overseas, you will require a Step Up Transformer.
Selecting the correct transformer
Check the Voltage. Look for the voltage rating on your appliance.
- If the rating reads similar to 100V-240V that means your product is dual voltage, it can be used without a transformer. (Many laptops, camera changers and mobile phone chargers are dual voltage, however, a plug adaptor is likely to be needed.)
- If the voltage rating states 110V or 120V it means the appliance is single volt and will require a Step Down Transformerto be used where the voltage is 220V (ie, in the UK)
- If the voltage rating states 220V or 240V it means the appliance is single volt and will require a Step Up Transformer to be used in abroad where the voltage is 110V.
Check the wattage. Now that you know you need a transformer, you need to determine which one or what size you need.
- Look for the watt rating on the appliance or calculate the wattage by multiplying voltage x amps. For example, 110V x 1.5A 165W.
- Select the transformer according to the wattage rating of your appliance.
- It is recommended using a transformer that is rated at least 25% higher than your products wattage rating.
- Using a transformer to their maximum capacity can eventually burn it out after prolonged use.
- Some items, such as laser printers or power tools, have a power spike or surge when they are first turned on, it is recommended that these types of products have a transformer that is at least double the products wattage rating.
Some transformers have two input sockets, if you decide to plug in two appliances into the one transformer; you must calculate the total wattage of the appliances.