Electronic Transformer FAQs
- Q) What is an electronic transformer composed of?
- A) Like a magnetic low voltage transformer, an electronic transformer contains an iron core and two sets of wires. In addition, it has an electronic device called an inverter. The inverter enables electronic transformers to be much smaller than magnetic transformers.
- Q) How does it work?
- A) Inverters in electronic transformers condition the current to change direction at a frequency of about 20,000-50,000 times per second (called 20,000-50,000 Hertz or Hz) as opposed to the "normal" power from your wall outlet, which changes direction at a frequency of 50Hz or 60Hz. The higher the frequency of the current, the smaller the low voltage transformer can be. Most electronic low voltage transformers provide high frequency AC output.
- Q) What are the advantages of using electronic transformers?
- A) They are very small and light compared to magnetic low voltage transformers; in most cases they are small enough that fixture manufacturers can often incorporate small electric transformers within their lighting fixtures rather than leaving the customer to find a hiding place. Even when not incorporated within the lighting fixture they are very easy to install in a small hidden location.
- Q) DO you have tips for wiring within the lighting circuit?
- A) Please make certain that the input wires (primary side) of the low voltage transformer are connected to the power line (120 volts) using wire nuts and that the output wires (secondary side) of the transformer are connected to the low-voltage light source using wire "terminal blocks" of appropriate size (for solid contact) for the transformer. Electronic low voltage halogen or xenon lighting systems carry relatively large currents, so all of the connections must be very tight to prevent arcing (a possible fire hazard) within those connections in a low-voltage electronic transformer. That’s why we recommend that you use terminal blocks. If a low-voltage transformer is equipped with wires, you will usually find that the thicker wires (larger gauge) are on the low voltage side of a product such as a 12v low voltage transformer, and the thinner wires (smaller gauge) are on the line voltage side.
- Q) How can I prevent a large voltage drop?
- A) The output of a low-voltage electronic transformer, unless it is a DC low voltage transformer, is high frequency (usually 20,000-50,000 Hertz). This means that there can be a substantial voltage drop if the wires carrying the high-frequency current are long, thin, or far apart. Always follow these rules to avoid a large voltage drop: Use thick (low gauge) wires on the secondary/output side. The thicker the wire, the less the voltage drop you will experience. The shorter the distance between transformer and lamp(s), the less the voltage drop you will experience. Try to use a pair of secondary wires that are twisted together in your electronic transformer. The closer the two output wires are to each other, the lower the voltage drop you will experience. When a low voltage transformer powers more than one fixture or circuit, split the output of the low-voltage transformer immediately into several separate circuits rather than carrying all the power in one pair of wires. The less power per circuit, the less the voltage drop you will experience in your electronic transformers. That is, a circuit with a total of 300 watts of load will have a greater voltage drop than a circuit with only 50 watts of load. A DC low voltage electronic transformer offers the only electronic solution that overcomes this type of voltage drop issue in a 12v low voltage transformer and other models.
- Q) Can electronic transformers be used with incandescent dimmers?
- A) Yes, most are compatible with common incandescent dimmers. However, we recommend using a dimmer specifically designed to handle an electronic low-voltage dimmer to make sure you don't lose dimming range and to avoid a hum during low light levels regulated by your low voltage electronic transformer.
- Q) How can a circuit that doesn't seem to be working be checked for problems?
- A) (1) Please make certain that the input wires (primary side) of the low voltage transformer are connected to the power line (120 volts or 277 volts) and that the output wires (secondary side) of the low voltage transformer are connected to the low voltage light source (12 volts or 24 volts). Most failures occur as a result of reverse or improper wiring in small electric transformers.
(2) Check the filament of the lamp to see if is burned out. (Remember the glass envelope of a halogen lamp should not be touched by bare hands because the natural oil from your hands will cause the lamp to burn out prematurely.)
(3) Check the connections of the lamp with the socket by moving the lamp inside the lamp holder.
(4) Since most voltmeters give misleading readings when applied to high frequency currents, the voltage on an electronic low voltage transformer can be measured only by using a "true RMS" voltmeter with a sufficient range.
- Here are five questions that will help you select the right electronic transformer for your needs.
- Plug-In or Hardwire
- 1. Do you need a plug-in electronic transformer? Yes or No
- 2. What wattage do you need?
[Hint: The wattage of the electronic transformer should always equal or exceed the total wattage of the entire lighting system.]
- 3. What voltage do you need? 12 volts or 24 volts
[Hint: 12-volt electronic transformers are often less expensive but 24-volt electronic transformers can power longer runs (circuits) of lighting. However, 24-volt electronic transformers must be used only with lamps (light bulbs) that are rated for 24V. If a 24-volt electronic transformer is used with lamps that are rated for only 12 volts, the lamps will burn out immediately.]
- AC or DC
- 4. Do you need an AC (alternating current) or a DC (direct current) electronic transformer?
[Hint: AC electronic transformers are often less expensive but DC electronic transformers can be placed at greater distances from the lighting system. An AC electronic transformer should not be placed any further than 10 feet from the lighting system while a DC electronic transformer may placed as far away as 50 feet.]
- Encased or Not
- 5. Do you need an electronic transformer that is encased (in a metal case)? Yes or No
[Hint: The metal case provides a safe and convenient storage space for the electrical splices (terminal block connections). If you select an electronic transformer that does not come in a metal case, it probably should be stored in some type of metal housing (e.g., a junction box).]