Triac BT 136 not working with load in MT1 terminal

Thread Starter

Interference

Joined Aug 24, 2020
4
Triac Bt 136 with load on Mt1 terminal not working as per attached connection diagram,Figure 3.

Its working with load in MT2 terminal, Figure 2,4,5.

Please explain with, whats wrong in figure 3, only load postion changed from Mt2 to Mt1.
 

Attachments

AlbertHall

Joined Jun 4, 2014
10,523
The gate to MT1 voltage is what triggers the triac. In the "not working with load on MT1" diagram, this voltage includes whatever the voltage is across the load. Connect the negative of the gate supply (Vg-) to MT1 instead of to the neutral.
 

Thread Starter

Interference

Joined Aug 24, 2020
4
The gate to MT1 voltage is what triggers the triac. In the "not working with load on MT1" diagram, this voltage includes whatever the voltage is across the load. Connect the negative of the gate supply (Vg-) to MT1 instead of to the neutral.
why its called bidirectional device, its load cannot be switched between Mt1 and Mt2.
when connected to an optoisolator, load can connect to Mt1.
 

Dodgydave

Joined Jun 22, 2012
9,632
Load should always be in the MT2, and triggered between G and MT1, .

It's called a bi direction switch because it works on AC voltage, so it fires on both cycles.
 

AlbertHall

Joined Jun 4, 2014
10,523
why its called bidirectional device, its load cannot be switched between Mt1 and Mt2.
when connected to an optoisolator, load can connect to Mt1.
Consider what happens to the voltage between gate and MT1 when the triac is switched on.
As the gate terminal is low resistance then it is likely that when the triac triggers that the MT2 to gate connection would be effectively a short circuit across the supply and destroy the triac.
 
Top