Intelligent Switches PDF

Learning Outcomes Describe the function of intelligent switches Describe the differences between intelligent switches and conventional switches (e.g., one-way and two-way switches or dimmers) Describe and program intelligent switches to control lighting and electrical devices 2.5.1...

Learning Outcomes Describe the function of intelligent switches Describe the differences between intelligent switches and conventional switches (e.g., one-way and two-way switches or dimmers) Describe and program intelligent switches to control lighting and electrical devices 2.5.1 Functions of Intelligent Switches An intelligent switch can be programmed to provide flexibility and multiple functions. It has two buttons, 0 and 1, which can be programmed to have different modes. There are four main modes: (a) Toggle (b) Off-On (c) On-Off (d) Dimming (a) Toggle Mode The lighting changes by pressing the button alternately, regardless of whether the 0 or 1 button is pressed. Fig. 2.5-1: Switch programmed to Toggle mode Unit 2.5 | Switching and Dimming 110 (b) Off-On Mode Pressing the top (0) button turns off the light. Pressing the bottom (1) button turns on the light. Fig. 2.5-2: Switch programmed to Off-On mode (c) On-Off Mode Pressing the top (0) button turns on the light. Pressing the bottom (1) button turns off the light. Fig. 2.5-3: Switch programmed to On-Off mode (d) Dimming Mode Pressing the top (0) button quickly turns off the light. Pressing and holding the top (0) button dims the light. Pressing the bottom (1) button quickly turns on the light. Pressing and holding the bottom (1) button brightens the light. Fig. 2.5-4: Switch programmed to Dimming mode Unit 2.5 | Switching and Dimming 111  2.5.2 Differences between Intelligent and Conventional Switches The conventional switches that we see in older homes and offices are mechanically operated; someone has to physically turn them on and off. They are different from intelligent switches, which: have an ID; are programmable; are maintained with a very low voltage; and are connected to other intelligent devices via network cables or wireless media. One-way and two-way switches or dimmers are examples of intelligent switches. 2.5.3 Conventional Switching Circuit In Fig. 2.5-5, the wiring has been connected such that the switch S1 controls the lamp L1 and the switch S2 controls the lamp L2. Fig. 2.5-5: Conventional switching circuit Unit 2.5 | Switching and Dimming 112 If the user wants S1 to control L2 and S2 to control L1 instead, the wiring has to be modified as shown in Fig. 2.5-6. This rewiring can be tedious, especially if the cables are concealed in the ceiling and walls. Fig. 2.5-6: Rewiring a conventional switch circuit Fig. 2.5-7 shows how one-way control can be converted into two-way control. The one-way switches would have to be replaced with two-way switches and the rewiring would be extensive. Fig. 2.5-7: Converting a one-way switch into a two-way switch To convert the switches in Fig. 2.5-7 from one-way to dimming control, both the one-way switches would have to be replaced with dimmer switches. Unit 2.5 | Switching and Dimming 113  2.5.4 Programming Intelligent Switches There are many types of intelligent switches available in the market. Most of these devices are programmable via software provided by the manufacturers. If the same one-way control circuit in Fig. 2.5-5 was installed with intelligent switches, these switches could be simply reprogrammed to achieve other possible desired outcomes (Fig. 2.5-8). Devices that are programmable via software are usually more flexible and provide more control features without having to rewire the circuit. Fig. 2.5-8: Installing intelligent switches Fig. 2.5-9 shows an example of how parameters are set for switching mode. Fig. 2.5-9: Parameters for an intelligent switch (switching mode) Fig. 2.5-10 shows an example of how parameters are set for dimming mode. Fig. 2.5-10: Parameters for an intelligent switch (dimming mode) There are also intelligent switches designed with built-in variable programmable functions, allowing users to select functions and set parameters, i.e., switching, dimming or blind-control functions. Such features provide users with the flexibility to set or program the devices without having to use software. Unit 2.5 | Switching and Dimming 114  2.5.5 Communication among Bus Devices We can look at the KNX bus system to better understand communication among bus devices. Fig. 2.5-11 shows a basic KNX bus system with its input devices (sensors) and output devices (actuators). Examples of sensors include push buttons, switches, occupancy sensors, temperature sensors and smoke detectors, while examples of actuators include switching, dimming and shutter actuators. The KNX bus system uses the group-addressing method for device-to-device communication. Each device has a unique device ID, indicated as 1.1.1 to 1.1.5 in Fig. 2.5-11. Depending on the functionality of the device, each device may have a different number of objects. Each object represents a particular function, such as switching or dimming. In order for two devices to communicate properly with each other, both devices must have an object with at least one group address in common. Group addresses often follow the form: 0/0/1, 0/0/2, 0/0/3, etc. The KNX bus system can use group addresses ranging up to 15/7/255. Fig. 2.5-11 shows the following: Since sensor 1 and switch actuator 1 have objects with the same group address of 0/0/1, this indicates that sensor 1 communicates with switch actuator 1. Since sensor 2 and switch actuator 2 have objects with the same group address of 0/0/2, this indicates that sensor 2 communicates with switch actuator 2. Since sensor 3 and switch actuators 1 and 2 have objects with the same group address of 0/0/3, this indicates that sensor 3 communicates with both switch actuators 1 and 2. Sensor 3 serves as the master switch since it controls two switch actuators. Fig. 2.5-11: Basic KNX bus system Unit 2.5 | Switching and Dimming 115