**2.4 External memory board (AL440B)**

This external memory board is one device of this power quality monitoring architecture to collect the fault data from ADUC7024 microcontroller into its memory in series. The data will be read by the LPC2368 microcontroller board and will be stored in SD-CARD for recalling or downloading later via the Ethernet network when of necessity needed. The circuit of the external memory board is shown in Fig. 6.

A Power Quality Monitoring System

Via the Ethernet Network Based on the Embedded System 237

the data frames continuously, and in the same time, the LPC2368 microcontroller board will

If the fault signal which is detected , in case, is an uncommon state, LPC2368 microcontroller board will control the ADUC7024 board to stop sampling and writing process temporarily, will read the sampling signal from the external memory board and will store the signal into SD-CARD. When it comes to the normal condition, both the microcontroller board will go

In case of the network that has the connection with Transmission Control Protocol/Internet Protocol (TCP/IP) and User Datagram Protocol (UDP) is established between the LPC2368 and the PC or laptop, we can monitor the status of power quality monitoring system hardware via the network in real time. In addition, the fault data can be downloaded from

The embedded software design is a flowchart of the two selected microcontrollers: ADUC7024 and LPC2368 used in this chapter. It is to explain the process of the power quality monitoring system based on the embedded system. For this embedded software design, there are the sampling concept, the power quality monitoring concept, data frame

attain the voltage and frequency data from ADE7758, as well.

Fig. 7. The power quality monitoring system hardware

the SD-CARD and displayed later when it is necessarily needed.

back to their usual tasks as before.

**3. Embedded software design**

and the Ethernet packet structures.

Fig. 6. The circuit of the external memory board

#### **2.5 The process of the power quality monitoring system**

The picture of the power quality monitoring system hardware is shown in Fig. 7, consisting of five parts as the followings:


From the architecture planned, the 3-phase AC lines connect to ADE7758 and to HCPL-788J for being measured of their voltages and frequencies by the ADE7758 board which is interfaced with the LPC2368 microcontroller board in order to acquire the voltage and frequency values and also to initialize the ADE7758 for detecting fault signal at one time. Then the HCPL-788J attenuates the voltage inputs and isolates the output signals. After that, the output signal is sent to become the signal inputs to the ADUC7024 microcontroller board for sampling waveforms and writing the sampling signals to the external memory board. In the ordinary state, the ADUC7024 microcontroller board will do the sampling and will write

Fig. 6. The circuit of the external memory board

2. Signal conditioning module board (HCPL-788J)

of five parts as the followings:

3. ADUC7024 microcontroller board 4. LPC2368 microcontroller board 5. External memory board (AL440B)

**2.5 The process of the power quality monitoring system** 

The picture of the power quality monitoring system hardware is shown in Fig. 7, consisting

From the architecture planned, the 3-phase AC lines connect to ADE7758 and to HCPL-788J for being measured of their voltages and frequencies by the ADE7758 board which is interfaced with the LPC2368 microcontroller board in order to acquire the voltage and frequency values and also to initialize the ADE7758 for detecting fault signal at one time. Then the HCPL-788J attenuates the voltage inputs and isolates the output signals. After that, the output signal is sent to become the signal inputs to the ADUC7024 microcontroller board for sampling waveforms and writing the sampling signals to the external memory board. In the ordinary state, the ADUC7024 microcontroller board will do the sampling and will write

1. The voltage and frequency measurement and fault detection board (ADE7758)

the data frames continuously, and in the same time, the LPC2368 microcontroller board will attain the voltage and frequency data from ADE7758, as well.

Fig. 7. The power quality monitoring system hardware

If the fault signal which is detected , in case, is an uncommon state, LPC2368 microcontroller board will control the ADUC7024 board to stop sampling and writing process temporarily, will read the sampling signal from the external memory board and will store the signal into SD-CARD. When it comes to the normal condition, both the microcontroller board will go back to their usual tasks as before.

In case of the network that has the connection with Transmission Control Protocol/Internet Protocol (TCP/IP) and User Datagram Protocol (UDP) is established between the LPC2368 and the PC or laptop, we can monitor the status of power quality monitoring system hardware via the network in real time. In addition, the fault data can be downloaded from the SD-CARD and displayed later when it is necessarily needed.
