Hands Free Faucets-The Power Source
Automatic faucets draw power from two popular sources: Six Volt seems to be the standard voltage for battery powered faucets (for now), although 9 volt is not uncommon. Battery powered faucets generally employ the services of AA batteries, C batteries, standard 9 Volt alkaline batteries, or lithium batteries. These batteries have storage capacities measured in milliamp/Hour, 1000 milliamp/hour is equivalent to 1 amp/hour which is enough energy to light up a 1 amp bulb for 1 hour. Larger size batteries exhibit greater energy capacity than smaller size batteries, similar to an automobile's gas tank, the larger the tank the more fuel you can put in it, but only efficient cars get the longer haul. Which brings us back to automatic faucets, no discussion of battery powered faucets is complete without briefly touching on faucet efficiency. How often you need to replace the batteries depends largely on how fast or slow the faucet consumes the energy stored within its batteries. This principally is a none-issue for AC powered faucets since wall AC is an inexhaustible power source, until the power goes out of course.
AC powered faucets employ transformers and switching adapters (more on those later) that plug into/or are hard wired to the wall. Transformers and switching adapters transform wall AC into 24, 12, 9, or 6 Volt AC or DC depending on the application. These are generally the 4 voltage ratings that automatic faucets operate on, at least here in the USA. Transformers and switching adapters measure their output capacity in VAC, higher VAC transformers and switching adapters are capable of delivering steady current at rated voltage to loads that require more "juice", in this case faucet electronics and solenoids. To better understand the relationship between VAC and power consumption by load, one only needs to look at automobile engines. The larger the engine, the larger the carburetor and fuel line that feed the engine. The larger the solenoid and electronics, the larger the VAC rating should be.
I mentioned switching adapters earlier which are commonly employed for the purpose of supplying power to electronic equipment. They are generally found along side laptops and cell phones. There are key reasons why switching adapters are the power supply of choice for electronic equipment manufacturers, automatic faucets are no exception. When employing standard transformers to supply power to modern electronic equipment, use of these transformers can lead to power quality degradation and heating problems, here are some of the reasons why:
- a. Single phase electronic loads can cause excessive transformer heating.
- b. Electronic loads draw "non-linear" currents, resulting in momentary low voltage supply and output voltage distortion.
- c. Oversizing for impedance and thermal performance can result in a transformer with a significantly larger footprint, and weight.
Switching adapters by contrast, are specifically designed for non-linear loads and incorporate substantial design improvements that address both thermal and power quality concerns. Such devices are low impedance, compact, and have better high frequency performance than standard transformers.