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[SOLVED] Stabilizer Reverse Engineering

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Okada

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I have been provided a task for reverse engineering. The data provided to me are Relays, LEDs and Switch connections and below mentioned data.

* AC input 110V - ADC 1.55V
* AC input 131V - ADC 1.86V
* AC input 135V - ADC 1.9V
* AC input 152V - ADC 2.17V
* AC input 156V - ADC 2.21V
* AC input 173V - ADC 2.49V
* AC input 176V - ADC 2.50V
* AC input 200V - ADC 2.90V
* AC input 205V - ADC 2.94V
* AC input 238V - ADC 3.49V
* AC input 242V - ADC 3.51V
* AC input 274V - ADC 4.10V
* AC input 280V - ADC 4.14V
* AC input 300V - ADC 4.50V
Click to expand...

*Input 280V = Output 0V. High Cut start. RL2 + RL3 on.
*Input 274V = output 230V, RL2 + RL3 + RL4 on.
*Input 242V = Output 204V. RL2 + RL3 + RL4 on.
*Input 238V = Output 233V. RL2 + RL4 on.
*Input 205V = Output 201V. RL2 + RL4 on.
*Input 200V = Output 235V. RL3 + RL4 on.
*Input 176V = Output 208V. RL3 + RL4 on.
*Input 173V = Output 238V. RL4 on.
*Input 156V = Output 216V. RL4 on.
*Input 152V = Output 239V. RL1 + RL3 + RL4 on.
*Input 135V = Output 212V. RL1 + RL3 + RL4 on.
*Input 131V = Output 241V. RL1 + RL4 on.
*Input 110V = Output 0V. RL1 on. Low cut start.
Click to expand...

I am having some problem in mapping mains voltage to relays state.

I want to know whether I have to turn ON RL1 if mains voltage is < 110V or should it be ON if it is between 110V and 131V ?

I think I should turn ON RL1 if mains voltage is < 110.

If I am wrong correct me.
 
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Can you determine what waveforms go through the relays? Do certain relays carry AC waveforms which are not in phase with the AC in other relays? Then it needs serious thought as to whether they should be allowed to combine waveforms.

Or... When relays are On simultaneously, is it so they can share a high current load among them? And the waveforms are all in phase? Then that should be okay.
 

Find attached Schematic. The Schematic file was drawn using Schematic models and I redraw the Simulation file using Simulation models. In Simulation file I replaced ADC interface circuit with POT.

In Original Circuit (Schematic) I have two doubts.

One is TIP122 is used and it is providing 22 * 1.4142 - 2.0 V to 12V relays. How does the relay survive ?

Another is MCLR circuit.

LEDs and Relays are named Properly in the two files and accordingly in the data I provided in post #1.

Only this much data is provided to me. Stabilizer using a Multi-Tapped Secondary Transformer.


Can you determine what waveforms go through the relays?
Click to expand...

It will take a week. I have asked the client to send one unit of Stabilizer for reverse engineering. I have Variac. I will do more tests.
 

Attachments

  • Schematic #1.PDF
    30.8 KB · Views: 91
  • Simulation #1.PDF
    37.3 KB · Views: 72

If the auxiliary supply to the sensing circuit is wound on the AVR transformer itself then the RL1 must be OFF below 110V. If done otherwise, sensing supply as well as relay driving supply will be too low to resume supply when mains input rises. The calculation of ADC sampling supply is not right since on every switching of RL1 & Rl2 this supply will vary considerably.
 

The calculation of ADC sampling supply is not right since on every switching of RL1 & Rl2 this supply will vary considerably.
Click to expand...

My client said that the adc input voltages were taken from a calibrated stabilizer by connecting a Varic to input and also corresponding relay states are noted when they change at a particular input voltage.

I can only do more testing when I get the stabilizer.

The transformer has two windings. One is multitapped and is used for relays to get output and another auxillary winding is to get 22V AC which after rectification powers the 12V relays.

Attached is simulation file.
 

Attachments

  • Simulation #1.rar
    35.2 KB · Views: 56

Sorry, I skipped the sensing circuitry. It is derived directly from mains. Hence my earlier observation is not correct. In that case also it is better to held RL1 off to ensure adequate supply to drive the relay/relays.

This arrangement has the risk of electrocution as it is not isolated.

- - - Updated - - -

One is TIP122 is used and it is providing 22 * 1.4142 - 2.0 V to 12V relays. How does the relay survive ?
Click to expand...

Why not? Have noticed that regulated supply is derived using series pass regulator circuit around TIP122, R13 resistor and D13 Zener? So why are you getting worried.
 

I am worried how 22 * 1.4142 - 2 = 29V gets converted to 12V for relay. This 29V is at 230V AC input. When mains is 300V AC it will be still higher.
 

Under the given arrangement voltage at "V-RELAY" point will be 15V - .6V = 14.4V approx. Would it be too much for 12V relay?
 

Why drop of 0.6 where there are two diodes in the bridge ?
 

I think you can not get me. I am not referring to .6V drop across the diode of bridge. I am telling about Vbe drop of TIP 122. Still not get me? Refer to formula of Series pass regulator.
 

Ok. I will check the series pass regulator in the book.

Here is stabilizer project. Report bugs after testing in Proteus or hardware.

- - - Updated - - -

Try RevD file. I fixed a small bug. The blinking was inverted.
 

Attachments

  • Test RevC.rar
    35.2 KB · Views: 53
  • Test RevD.rar
    35.1 KB · Views: 57

It is really not clear to me what you mean by uploading the video.
 

Uploading means I can't upload the video to youtube and post the youtube link here. The video resoultion degrades in youtube. Here if youtube link is posted in video tags then it will show video window and users can play the video and see it here only.
 

Fixed a bug. When voltage was returning from low or high volt to normal volt the red, yellow and green Leds were ON.
 

Attachments

  • Test RevE.rar
    35.4 KB · Views: 59

Completed the project. Here is the video link. I didn't attach the file here because it is 227 MB.

https://www.mediafire.com/?ergkzk688hhxr1x

In video from top

1st LED is Normal Voltage
2nd LED is Delay
3rd LED is High Voltage
4th LED is Low Voltage
5th is Relay 1
6th is Relay 2
7th is Relay 3
8th is Relay 4

When stabilizer returns to normal state from low or high cut-off state then based on the delay switch position the delay led will blink 10 seconds or 3 minutes and then normal led turns ON and then after 2 second delay the relay state changes but when stabilizer state changes to low or high cut-ff state from normal or any state then low/high led and delay led will turn on instantly.

If stabilizer is already running delay (delay led blinking) and voltages shifts to cut-off state then current delay is terminated and stabilizer enters cut-off state.
 
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