BTA41600B and MOC3063

[2001dragon]

Hi everyone, i'm a newbie in eletronics and not good at english. I want to ask about the triac BTA41600B and opto MOC3063. According to datasheet of BTA41, it has pins named as A1, A2, G. I connected A1 to 220V AC supply and I found that G also has 220V AC which i don't know why. I thought if I connected A1 to 200V AC then I triggered gate G and A2 would have 220V AC. This is confusing me because I don't know how to trigger G when it has 220V AC already. If anyone has time, please help me understand how it works and how I can use MOC3063 to trigger BTA41. A circuit diagram would help me alot too (I don't really understand the use of R and C in datasheet of MOC3063)

Thanks in advance!

P/S: please be easy on me, i'm still learning from scratch (not from school though)

 

[cowboybob]

Not sure why you're asking for a circuit diagram for using the BTA41600B since you seem to have one already, referring to the MOC3063 datasheet.

The series RC circuit across the output is called a "snubber", these are for reducing inductive "kick" (a strong reverse current) from an inductive (as opposed to a "resistive") load.

 

[alec_t]

I found that G also has 220V AC which i don't know why

G is internally effectively connected via a couple of pn junctions to the main (A) terminals, so Vga is ~ 1.4V.

 

[dr pepper]

Thats a bit of a beefy triac to be playing with, esp for a noob.
What are you building?

 

[2001dragon]

I have a board which is used to run a DC motor, a 3-phases motor, controlled by 2 proximity sensors. I want to recreate that board because it's sold for a high price and I need alot of them. So I investigated the board and saw that 220V AC input is connected to A1, A2 is connected to pin4 of MOC3063, G is connected to pin6 of MOC3063 through a R. Pin1,2 of MOC3063 are connected to ATMEGA8. So I asked because I don't know how current flows in triac and MOC. If anyone can explain it for me, I would be very appreciated. Thanks!

 

[dr pepper]

I think there might be an issue with your english here.
A 3 phase motor by definition is an ac motor not dc.
Sounds like either your building an ac drive that produces 3 phase ac from dc (like commercial ones do), or maybe its a 3 phase to dc scr speed controller for a dc motor.

 

[alec_t]

I don't know how current flows in triac and MOC

A small DC current via pins 1 and 2 of the MOC lights a LED inside which is electrically-isolated from but turns on a small light-sensitive triac. This triac in turn is used as a switch between the gate and A2 of the larger triac to turn on the latter. The R and C damp any transients which might cause false switching of the larger triac.

A 3 phase motor by definition is an ac motor not dc

How about a 3-phase BLDC motor, such as is used in washing-machines etc?

 

[2001dragon]

Thanks for reply.

I think there might be an issue with your english here.
A 3 phase motor by definition is an ac motor not dc.

Yes, I know I'm not good at english. And the system is DC motor always running, sensors are used to start and stop 3 phases AC motor.

There is another problem that I can't not find a datasheet for 3 devices coded B1121 (1st line) 817C (2nd line). They are between the ATMEGA8 and sensors, each output of sensors is connected to one B1121. I'm not sure what devices these are so I don't know what they do

 

[dr pepper]

Fisher and paykel bldc motors used in washing machines are indeed ac, the incomming mains is rectified to dc and then commutated into ac to fire the windings.