Hardware Reference
In-Depth Information
these require the switch on the wall socket to remain permanently on, along with any switch on the appliance itself.
This further implies that any device plugged into such a module that could be controlled remotely must be safe at all
times. In the case of the teakettles, for example, it must contain enough water so it won't boil dry.
Appliance Module (AM12U)
Like its sister module, the LM12U, this is a very simple “plug in and go” device that, although it looks the same
(see Figure
1-7
), has three very important differences:
u
It has no dimmer support
u
It can control fluorescent lights
u
It can operate at much higher loads (up to 500W for incandescent lamps, 1A for inductive
3
appliances like fans, and 16A for resistive loads
4
such as heaters)
Figure 1-7.
The AM12U, 52 × 122 × 33mm
Consequently, its intended purpose is to automate units such as fans and teakettles. However, high-power
devices such as vacuum cleaners and fan heaters rarely work on these modules because of the back-EMF created by
the collapsing magnetic field around the motor when it is switched on or off. This back-EMF generates a large voltage
spike that can blow the fuse in the AM12U (if you're lucky) or the device (if you're unlucky).
)NDUCTIVELOADSUSEMAGNETICFIELDSANDAREUSUALLYCHARACTERIZEDBYMOTORSORSOLENOIDS
2ESISTIVELOADSCONVERTELECTRICALCURRENTINTOOTHERFORMSOFENERGYSUCHASHEAT
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