3-phase voltage monitoring relay

[bluethunder7000]

5989-2137en.pdf

hi

i want to design a 3-phase voltage monitoring relay which acts as an under/over voltage relay using the microcontroller so i need the hardware design for a circuit of this device

i any one have any suggetions i will be thanks


thanks again

 

[glenjoy]

Can't understand clearly what do you want to happen, care to give the flowchart or description.

 

[IanP]

You will need 3 low-power transformers which will transform voltage from 230 (star configuration with neutral in the middle) or 440/380 (between phases) to, say 6Vac. Voltage from each transformer will be rectified and feed to ADC, so you can measure these voltages.
As relay you can use power rating contactor (obviously signal from microcontroller pin has to be amplified to be able to operate this contactor) or for fast swiching - 3 solid state relays (20ms reaction time).
Once a microcontroller (with interna/external analog-to-digital converter(s)) seneses missing phase or lower/higher voltage it will send signal to a "relay" and disconnect power ..

 

[bluethunder7000]

hi Ianp

i know the process of this relay but i need to know what is the type of the low power transformer and i need it so small as i can put it on board with the microcontroller

if you have any schematic or any soft copy about this subject i will be thanks

thank you

 

[IanP]

These transformers can be the smallest available on the market. Their purpose is to transform voltage - no power, so I guess they can be rated for ≤ 2VA and you should be able to install them directly on your PCB.
At this moment I don't have any drawing at hand but I will try to post someting later ..

 

[artem]

Use optocouplers - cheap and universal .
In simplest implementation optrones (if you need to monitor status for all 3 pahses ) should be on when voltage is in range and of when ot.

Or you can bring some intelligence - take small micro either with software or hardware uart and send status information via one single optron to your host mcu (of course equipped with uart as well ) .
If you will equip your detection part with rechargable battery - status will be known even there is no AC voltage . Otherwise you have to guess what was happened - either small mcu failure or AC outage .

 

[marie65]

You can use this resistor based input circuit for 3 phase 380V with neutral. All resistors are 0.5W.
Marie65

 

[bluethunder7000]

i read the all of ideas and i want ask are the transformer is good for this application or the voltage divider and what the differece between them and what is the recommended methods in this application

you know that when i will make this device i must put it in small case so the volume and dimensions of the components it is most important to me

so i need any one have any ideas for the almost component

 

[hcet]

Hi bluethunder7000,
this article is written in German but even if you don't understand the language it gives you maybe some inspiration.
**broken link removed**
You can download the whole article as PDF here:
**broken link removed**

 

[marie65]

i read the all of ideas and i want ask are the transformer is good for this application or the voltage divider and what the differece between them and what is the recommended methods in this application

The transformer method is good because you can use it even if the power line is without neutral (delta) and also you will have galvanic separation between power lines and your micro. This will help a lot during development and debugging period.
The resistor method is cheaper and smaller in volume but no isolation to live lines.

 

[bluethunder7000]

hi

the german pdf is indicated to the microprocessor of texas instruments but i will make it with motorola microcontroller

i know that the transformer methods is good for isolation but i need specific type of it with small volume to but it in the borad and with range (0-450 volt)

thanks

 

[IanP]

Just another thought:
Can you use high-linearity analog optoisolator?
The HCNR200/2001 is used in analoh voltage and (4-20mA) current isolation applications.
Here is its data sheet with examples:
**broken link removed**

 

[bluethunder7000]

hi

i saw a destroyed under/over voltage relay and i saw that there is no transformer for 3- phases of line and it work using pic microcontroller so i need to know how can connect the 220vac to microcontroller without transformer and if there any collage project or any thing else can show me the schematic of the hardware of this relay

thanks

 

[bluethunder7000]

hi

there any one have a replay for the above subject ( schematic and hardware )

 

[bluethunder7000]

hi

i would like to know a lot about the marie65 attachment ( resistor methode ) and how can connect it to microcontroller to detect the zero crossing and voltage level so if there anyone know any idea about this circuit and if there any documents for it pm me

thanks