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triac

In this example of using a 3Q triac, could the AC voltage flow into the DC terminal?

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If the DC source is floating, as shown, and the DC source is more than 2-3V, then current will not flow out of the source (Ig will be zero or negative, depending on the switch position).

If the triac fails or the connection to MT1 fails, then excessive current could flow in either direction.

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  • \$\begingroup\$ Thanks for your feedback. I am using a power module to convert the 24 VAC into 5 VDC. The source of the 24VDC for the power module is Vs in the circuit above. \$\endgroup\$ – user3496475 Sep 15 '14 at 2:19
  • \$\begingroup\$ Thanks for your feedback. I am using a power module to convert the 24 VAC into 5 VDC. The source of the 24VDC for the power module is Vs in the circuit above. Whats happening in my case is that when I disconnect the positive terminal of the power module, I still see a Voltage drop across the triac of about 14 VDC. If I disconnect the negative terminal of the power module, I get 12 VDC. Does this mean that my power module(source for the 5V DC) is not floating. This is my power module: R-78C5.0-1.0 \$\endgroup\$ – user3496475 Sep 15 '14 at 2:26
  • \$\begingroup\$ If the triac stays 'on' when the positive terminal is disconnected, then it's not floating. Perhaps it is grounded. \$\endgroup\$ – Spehro Pefhany Sep 15 '14 at 2:32
  • \$\begingroup\$ I agree. The power module has three pins. P1 connects to 24VAC Live. P2 connects to the Neutral for the AC supply. P2 is also the ground for the DC supply. P3 is the 5VDC output. How can I convert this configuration to floating using the same power module. Really appreciate your help Spehro. \$\endgroup\$ – user3496475 Sep 15 '14 at 3:00
  • \$\begingroup\$ I need to clarify. P1 and P2 on the power module take the fully rectified input from a bridge rectifier. So essentially... The 24 VAC is connected to a bridge rectifier and the output from the bridge rectifier is connected to P1 and P2 on the power module. And P2 is also the Ground for my VDC circuit while P3 is at 5VDC with respect to P2. \$\endgroup\$ – user3496475 Sep 15 '14 at 3:33

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