Delta connected load on- off control

Thread Starter

ilginsarican

Joined Jul 13, 2017
137
Hi,
I have to on-off switch a AC load, which delta connected 3 phase AC source.
Consider the load that will be switched on-off is Z1.
To achieve on-off switch, I think use zero cross triac opto driver and triac for both Phase-R and Phase-Y.
But I am confused.
When Phase-R reaches zero point, triac will be closed but, Phase-Y won't be zero beacuse of 120degree phase angle.
Will this situation damage the load? Does it cause any problems?
Is phase control required?


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Ian0

Joined Aug 7, 2020
3,280
Z1 doesn't actually know that it's on a three-phase supply.
Just ignore the blue phase, and treat it as though Red were Live and Yellow were Neutral in a single phase situation.
 

Thread Starter

ilginsarican

Joined Jul 13, 2017
137
Z1 doesn't actually know that it's on a three-phase supply.
Just ignore the blue phase, and treat it as though Red were Live and Yellow were Neutral in a single phase situation.
Hello again,
I have a single phase AC-DC converter.
As I mentioned above, is it possible to feed converter from 2 phase of delta system as long as voltage and frequency range are provided?
 

Ian0

Joined Aug 7, 2020
3,280
Hello again,
I have a single phase AC-DC converter.
As I mentioned above, is it possible to feed converter from 2 phase of delta system as long as voltage and frequency range are provided?
Again, it just looks like any other single phase supply to the converter. Don't forget that the phase-to-phase voltage is √3 x the phase-to-neutral voltage.
 

Thread Starter

ilginsarican

Joined Jul 13, 2017
137
Again, it just looks like any other single phase supply to the converter. Don't forget that the phase-to-phase voltage is √3 x the phase-to-neutral voltage.
Hi again,i had a similar question(unfortunately).
I want to use microchip's MCP39F521 single phase Power Monitor IC.
According to the schematics, neutral is connected to analog ground, to measure voltage this is this is how it should be.
But I will take two phases from source, no neutral.So I have to connect second phase to analog ground. Will this cause a problem?
 

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Ian0

Joined Aug 7, 2020
3,280
How do you propose to connect the MCP39F521 to your microcontroller?
I would recommend powering from your microcontroller’s supply and connecting the voltage and current inputs via transformers. Otherwise you have to produce an isolated 3.3V supply with its 0V connected to one of the phases, and then isolate the data.
 

Ian0

Joined Aug 7, 2020
3,280
Hi again,i had a similar question(unfortunately).
I want to use microchip's MCP39F521 single phase Power Monitor IC.
According to the schematics, neutral is connected to analog ground, to measure voltage this is this is how it should be.
But I will take two phases from source, no neutral.So I have to connect second phase to analog ground. Will this cause a problem?
Did you know that Microchip have a cheaper one called ATM90E26?
seems to do just the same for half the price.
 

Thread Starter

ilginsarican

Joined Jul 13, 2017
137
How do you propose to connect the MCP39F521 to your microcontroller?
I would recommend powering from your microcontroller’s supply and connecting the voltage and current inputs via transformers. Otherwise you have to produce an isolated 3.3V supply with its 0V connected to one of the phases, and then isolate the data.
Hi, Thanks for your advice.
I will use 5V to 5V isolated DC DC module to suppy the IC , nd for I'C digital isolator.
 

Thread Starter

ilginsarican

Joined Jul 13, 2017
137
How do you propose to connect the MCP39F521 to your microcontroller?
I would recommend powering from your microcontroller’s supply and connecting the voltage and current inputs via transformers. Otherwise you have to produce an isolated 3.3V supply with its 0V connected to one of the phases, and then isolate the data.
Hello again,
I will connect the phase-2 to the ground of isolated 3.3V via a ferrite, phase-2 as if neutral.
 
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