GSM controller...

The real nasty part starts here!!

In order to wirelessly control the generator I need the microcontroller to be able to recognize the massage (SMS) received from the authentic user.

Then in order to warn the user, I need the microcontroller to be able to send warning/failure massage to the user autonomously.

STEP 1

I needed a mobile which supports "AT-Commands" and which is compatible with a serial cable. After a lot of search, I finally got "Samsung C-130" along with a serial cable.

It cost me 800Rs. for the cell phone and 120Rs. for the cable.. ;)

STEP 2

Now I needed to make sure of the mobile operates properly with AT-Commands.
So I hooked up the mobile with my PC via serial port and sent commands through Hyperterminal at a BAUD rate of 4800bps and without any flow control.

BINGO... It worked out perfect at the very first try !!

continued in next post...

Now the RTC...

I'm using "DS-1307" for RTC (Real Time Clock). I've used I2C (Inter Integrated Circuit) protocol (aka the TWI-Two Wire Interface) to hook up this IC.

It can not only manage time with accuracy up-to 1 second, but it also manages complete calender with day, date,weeks passed,months and years. And it also caters for the leap year:)


"Here" is a link to the data sheet.

Another thing worth mentioning that this IC can maintain time and complete calender for up-to "10 Years" with a single Li-Ion (3Volts) backup cell.

Lets start with LCD...

I'm going to use a 16X4 LCD. I've successfully interfaced the LCD with the microcontroller. I can now display all sort of text and custom characters I want.
This would help me at a later stage when I would have to create menus and other sorts of visual aids.


Click "HERE" for the datasheet.

SCHEDULE

Well here's the schedule...

Some Unique Features...

GSM

• Remote ON and OFF
• Failure Warning

RTC

• Time Reset
• Date Reset
• Mobil Oil Change Timer
• ON/OFF timer

LCD

• Different menus and options for visual interface

My Mission...

"I plan to develop a Cost-effective automatic transfer switch
with advanced user friendly features for convenient operation."

• Compatibility for NATURAL GAS generators
• Compatibility for GASOLINE generators
• ON/OFF time scheduling
• LCD display for user friendly interface
• Wireless operation via GSM
• On board time/ calendar management
• On board keys for easy interface
• Reduced size for easy installation

Related Domains

To accomplish this task I would require expertise in the following domain...

• Power Electronics
• Software [Programming /C++]
• Embedded System Design
• Control System Design

Block diagram

Here is the block-diagram of the proposed system.



I'm going to be working on each block one by one.

ATS Classification

There are two broad categories of ATS systems available in the market:
1- Industrial Generator ATS
2- Household Generator ATS

Industrial Generator ATS

These systems are designed for heavy duty industrial generators, with power rating of >10kv.
Such generators are mostly diesel based.

Some Common features of Industrial Gen. ATS:
* Temperature Monitoring
* Pressure / Humidity Monitors
* Current / Voltage monitoring
* Data Logging
* Load Monitoring
* Warning System
* Manual Override
* Auto Ignition
* Maintenance Mode

Household Generator ATS

These systems are compatible with generators with power rating between 1KVA to 6KVA.
Such generators are usually fueled by Petrol, Diesel or Natural Gas.

Some feature of common commercial ATS systems are:

* Auto Ignition
* Load Transfer
* Auto Turn Off
* No Interactive Panels

An Overview of ATS systems in Pakistani Markets

ATS systems in Pakistani markets are limited only to the affording costumers due to the following constraints:

* ATS panels available are not compatible with natural gas generators, but only with gasoline and diesel generators.
* High unit price (25,000 PKR ++)
* High installation Charge (1,500 to 4,000 PKR)
* Lots of hidden charges
i.e. contactors, casing, mounting clamps, wire, etc..
* Chinese vendors are less durable, unreliable and offer no warranty or guarantee.

Installation Topology of a Transfer Switch

A basic home electrical service looks like this (grounding circuits and wires have been left out in order to make the drawings less cluttered):Figure 1-Home electrical service before the installation of a standby generator and transfer switch

The meter is fed from the utility via an overhead or underground conduit as shown in figure. The electrical service main disconnect and electrical distribution panel are shown as 2 separate items, however newer circuit breaker distribution panels have the main disconnect located at the top of the electrical distribution panel (large circuit breaker).

Adding a standby generator into your electrical service system

The circuits that you want to be powered by both the electrical utility and the standby generator are transferred to the generator electrical distribution panel. The generators electrical distribution panel should be fed from a double (2-pole) breaker in the main distribution panel.


Figure 2 - Standby generator and transfer switch installed in a home electrical service.

Simplified inner workings of the transfer switch are shown in Figures 3 and 4. For clarity have been shown with a manual lever. If you have an automatic transfer switch the electrical switching function works in the same manner as the manual switch.

The drawings also show the switching of the neutral wire (white). Many systems do not switch the neutral wire and tie the three neutral wires together. Verify the method of wiring with your transfer switch and generator before installation.

Figure 3 - Wiring Diagram Of A Manual Transfer Switch In The "Off" Position

Figure 4 - Wiring Diagram Of A Manual Transfer Switch In The "ON" Position

When utility power is functioning the wires from the circuit breaker in the main electrical distribution panel are connected to the generator sub-panel. If utility power fails, the switch connects the generator's power to the circuits in the generator sub-panel.

Transfer Switch

The transfer switch is the device that transfers the power from the utilities power to the standby generators power.

If you are installing a standby generator in order to have some electrical power to your home in the event of a utility power outage, you have to install a transfer switch.

There are two methods to perform the transfer:

• Manual

In the case of the manual transfer switch, it requires that someone recognizes that the utility power has failed and must intervene to start the generator and then transfer the desired circuits to the generators power output. A manual transfer switch does not operate if there is no one at home.

• Automatic

In the case of an automatic transfer switch (ATS), the switch has the intelligence to sense when the utility is no longer delivering power and automatically starting the generator and then transferring the circuits to the generator. The automatic transfer switch also recognizes when the utility power is back online, transfers the circuits back to the utility and turns the generator off.