This new circuit idea is partially an offshoot from my previous discussion:
http://forum.allaboutcircuits.com/t...aling-with-voltage-spikes.100777/#post-760288
We have carbonator pump motors (240VAC, 1/3HP, ~2amps when running) in our machines that we currently switch with DPDT relays, except for machines being produced for Australia, where we use SSRs that are only switching one leg. We'd like to go solid-state on all machines to get away from noise issues that seem to be coming from the relay (arcing issues, maybe?) but for the US market, both legs have to be switched and 2 SSRs per motor gets bulky and expensive.
I have an idea for a simple circuit to switch both legs with triacs. I found the Littelfuse Q6040K7TP (manufacturer's docs here) which claims not to require a snubber circuit, even with highly inductive loads. It seems too good to be true, but it looks like with two triacs and two properly sized resistors, I can do what two big SSRs do, for less cost than a single SSR.
Am I missing something here? Is this basic idea sound? If so, any advice on modifications that would make it better? I'm very new at all this - getting better at picking out concepts but have so much to learn on all the specifics!
Assuming I've got the idea right, the resistors need to be sized to deliver more than the minimum gate current (100mA) and less than the absolute max (4A). I'm assuming it's better to stay near the low end, so maybe ~1200 ohms which would deliver 200mA @240VAC, meaning 48 watts that each resistor has to handle.
Thanks in advance!
http://forum.allaboutcircuits.com/t...aling-with-voltage-spikes.100777/#post-760288
We have carbonator pump motors (240VAC, 1/3HP, ~2amps when running) in our machines that we currently switch with DPDT relays, except for machines being produced for Australia, where we use SSRs that are only switching one leg. We'd like to go solid-state on all machines to get away from noise issues that seem to be coming from the relay (arcing issues, maybe?) but for the US market, both legs have to be switched and 2 SSRs per motor gets bulky and expensive.
I have an idea for a simple circuit to switch both legs with triacs. I found the Littelfuse Q6040K7TP (manufacturer's docs here) which claims not to require a snubber circuit, even with highly inductive loads. It seems too good to be true, but it looks like with two triacs and two properly sized resistors, I can do what two big SSRs do, for less cost than a single SSR.
Am I missing something here? Is this basic idea sound? If so, any advice on modifications that would make it better? I'm very new at all this - getting better at picking out concepts but have so much to learn on all the specifics!
Assuming I've got the idea right, the resistors need to be sized to deliver more than the minimum gate current (100mA) and less than the absolute max (4A). I'm assuming it's better to stay near the low end, so maybe ~1200 ohms which would deliver 200mA @240VAC, meaning 48 watts that each resistor has to handle.
Thanks in advance!