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Voltage and Amps questions


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Gday all

I plan to run a 16 channel controllers with 240v on the one side and 24v on the other side, how many amps can be drawn at each voltage? I understand that at 110v you can draw a max of 20 amps but I presume it would be around 10 amps at 240v and higher at 24v, I can get a transformer which outputs 25v at 20 amps but am not sure if this is ok. Just thought I would ask you blokes in this excellent forum to make sure.
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If I understand this, you are wanting to operate one side of a 16 channel board off of 240 volt power, and have it driving eight 240 volt loads, and operate the other side of the controller from 24 volt power and drive eight 24 volt loads???

First of all there are 2 amperage limitations, the first is total amps (per side) which is a function of the fuse rating, input wire size, and current capacity of the traces on the PC board. It is not a function of your input voltage.

The 2nd limit is the per-channel current which is determined by the current rating of the triacs and heat sink capacity. I believe this is spec'd at 2A without heatsinks and 8A with heatsinks, although you can't draw the 8-amp maximum from more than 2 channels simultaneously without exceeding the total per-side current rating.

So, as far as that part of your question goes, the amp limits will not change for different operating voltages.

The next problem is whether or not the controller can even operate on anything other than 120 volts input power. I am almost positive that it would not work on 24 volts, the problem being that the input voltage is also powering the controller itself, and the on-board power suply that powers the controller electronics probably needs 120v to operate. As far as the 240 volt operation goes, I just don't know. I have seen the 120v/240v references in the on-line documentation but the silk-screening on the boards just says 120v.

Another issue is that it is not good practice to mix low and high voltage circuits in the same enclosure. At least in the US, this would not be an acceptable practice as there is a danger of an inadvertent path between the 2 sides that would put the higher voltage on a low voltage circuit.

A possibilty I suppose would be to use separate step-down transformers on each output channel to get the 24 volts for your low-voltage loads. Even this may not work since the transformers are expecting a pure sine-wave input rather than the clipped sine wave output of the controller's triacs.

-jim-







bocco wrote:

Gday all

I plan to run a 16 channel controllers with 240v on the one side and 24v on the other side, how many amps can be drawn at each voltage? I understand that at 110v you can draw a max of 20 amps but I presume it would be around 10 amps at 240v and higher at 24v, I can get a transformer which outputs 25v at 20 amps but am not sure if this is ok. Just thought I would ask you blokes in this excellent forum to make sure.
:]
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If I understand this, you are wanting to operate one side of a 16 channel board off of 240 volt power, and have it driving eight 240 volt loads, and operate the other side of the controller from 24 volt power and drive eight 24 volt loads???
The next problem is whether or not the controller can even operate on anything other than 120 volts input power. I am almost positive that it would not work on 24 volts, the problem being that the input voltage is also powering the controller itself, and the on-board power suply that powers the controller electronics probably needs 120v to operate. As far as the 240 volt operation goes, I just don't know. I have seen the 120v/240v references in the on-line documentation but the silk-screening on the boards just says 120v.


Correct.

And this seems possible from the other posts I have searched http://planetchristmas.mywowbb.com/view_topic.php?id=1505&forum_id=25&highlight=australia note post by Geoff Harvey.


First of all there are 2 amperage limitations, the first is total amps (per side) which is a function of the fuse rating, input wire size, and current capacity of the traces on the PC board. It is not a function of your input voltage.

The 2nd limit is the per-channel current which is determined by the current rating of the triacs and heat sink capacity. I believe this is spec'd at 2A without heatsinks and 8A with heatsinks, although you can't draw the 8-amp maximum from more than 2 channels simultaneously without exceeding the total per-side current rating.


So, as far as that part of your question goes, the amp limits will not change for different operating voltages



This I all understand 8*8=64amps to much:(, but with reference to voltage the board can handle a max of 20 amps per side say 110v @ 20amps =2200watts but at 240v @ 20amps = 4800 watts (not likely on Aus standards a max of 10 amps only can be drawn from a standard GPO) but at 24V @ 20amps= 480watts, but this is high current at 24v thicker conductors wires ect for low wattage comparativley speaking I have calculated my wattage draw to be around 300watts @24v =12.5amps.But I dont want to burn out the tracks, fuses ect so my real question is what are will the triacs boards ect handle at each voltage?




Another issue is that it is not good practice to mix low and high voltage circuits in the same enclosure. At least in the US, this would not be an acceptable practice as there is a danger of an inadvertent path between the 2 sides that would put the higher voltage on a low voltage circuit.

A possibilty I suppose would be to use separate step-down transformers on each output channel to get the 24 volts for your low-voltage loads. Even this may not work since the transformers are expecting a pure sine-wave input rather than the clipped sine wave output of the controller's triacs.





I know It's not good but our regs are more stringent on 240v in regards to garden festive lighting ect thus most of it is low voltage, I can only be very stringent in the setup using RCD's ect. The transformer issue on the switching side is what I am trying to avoid hopefully I don't think they would last rapid switching and dimming also return current back into the controller might also cause problems. Another thought has come to me that I could join two 110v strings in series to get around this but it means importing from overseas ect, more hassle. I guess that the pioneering spirit may need to be used.
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bocco wrote:

If I understand this, you are wanting to operate one side of a 16 channel board off of 240 volt power, and have it driving eight 240 volt loads, and operate the other side of the controller from 24 volt power and drive eight 24 volt loads???
The next problem is whether or not the controller can even operate on anything other than 120 volts input power. I am almost positive that it would not work on 24 volts, the problem being that the input voltage is also powering the controller itself, and the on-board power suply that powers the controller electronics probably needs 120v to operate. As far as the 240 volt operation goes, I just don't know. I have seen the 120v/240v references in the on-line documentation but the silk-screening on the boards just says 120v.


Correct.

And this seems possible from the other posts I have searched http://planetchristmas.mywowbb.com/view_topic.php?id=1505&forum_id=25&highlight=australia note post by Geoff Harvey.

Ah! Yes, I see that the controller electronics are powered from just one side, which certainly makes sense.



First of all there are 2 amperage limitations, the first is total amps (per side) which is a function of the fuse rating, input wire size, and current capacity of the traces on the PC board. It is not a function of your input voltage.

The 2nd limit is the per-channel current which is determined by the current rating of the triacs and heat sink capacity. I believe this is spec'd at 2A without heatsinks and 8A with heatsinks, although you can't draw the 8-amp maximum from more than 2 channels simultaneously without exceeding the total per-side current rating.


So, as far as that part of your question goes, the amp limits will not change for different operating voltages



This I all understand 8*8=64amps to much:(, but with reference to voltage the board can handle a max of 20 amps per side say 110v @ 20amps =2200watts but at 240v @ 20amps = 4800 watts (not likely on Aus standards a max of 10 amps only can be drawn from a standard GPO) but at 24V @ 20amps= 480watts, but this is high current at 24v thicker conductors wires ect for low wattage comparativley speaking I have calculated my wattage draw to be around 300watts @24v =12.5amps.But I dont want to burn out the tracks, fuses ect so my real question is what are will the triacs boards ect handle at each voltage?

Unless I am way off base, the 8 amp per channel rating (with heat sinks) would not change regardless of whether you were using 24v, 120v, or 240v. The heat generated by the triac is the product of the voltage drop across the triac (not a function of applied voltage) and the current. So your 24v side would be limited to 8A or about 200 wats max per channel, and 20A or about 500 watts maximum combined for all 8 channels.




A possibilty I suppose would be to use separate step-down transformers on each output channel to get the 24 volts for your low-voltage loads. Even this may not work since the transformers are expecting a pure sine-wave input rather than the clipped sine wave output of the controller's triacs.




Sorry for the weird formatting here but I can't get the cursor to drop below the last part of your quote. I can see why you would want to avoid transformers. Another option might be solid state relays. Drive the relays from the controller at 240 volts, then have the relays switch the 24 volts to your loads. This probably wouldn't work for dimming although it might if your SSRs were not of the 'switch on zero crossing' type.

-jim-


I know It's not good but our regs are more stringent on 240v in regards to garden festive lighting ect thus most of it is low voltage, I can only be very stringent in the setup using RCD's ect. The transformer issue on the switching side is what I am trying to avoid hopefully I don't think they would last rapid switching and dimming also return current back into the controller might also cause problems. Another thought has come to me that I could join two 110v strings in series to get around this but it means importing from overseas ect, more hassle. I guess that the pioneering spirit may need to be used.

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Unless I am way off base, the 8 amp per channel rating (with heat sinks) would not change regardless of whether you were using 24v, 120v, or 240v. The heat generated by the triac is the product of the voltage drop across the triac (not a function of applied voltage) and the current. So your 24v side would be limited to 8A or about 200 wats max per channel, and 20A or about 500 watts maximum combined for all 8 channels.


This is what I thought also but on some components you see ratings for different volatages ect. I guess a trial and error approach will be needed here.



Another option might be solid state relays. Drive the relays from the controller at 240 volts, then have the relays switch the 24 volts to your loads. This probably wouldn't work for dimming although it might if your SSRs were not of the 'switch on zero crossing' type.

I may use this as a last resort.

Thanks very much -jim-
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I just looked at a 16 channel board. It appears that the right side (channels 9-16) is where logic power is derived. This side has to be powered with either 120v or 240v and the jumper must be set to the corresponding position.

The left side (channels 1-8) AC wiring is independent and should work with just about any ac source voltage as long as the voltage rating of the triacs isn't exceeded.

So you should be able to connect your 24v ac supply to the left side of the board and control eight 24 volt loads as long as you are within the 8A/chan and 20A/total rating for that side.

-jim-

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  • 2 weeks later...
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What the original poster is proposing will work just fine on the 16 channel controllers. The power for the controller itself is derived from channels 9-16. You should be able to set the jumpers for 240 and attached 240v input to channels 9-16, then the other channels could be any AC voltage within the limits of the triacs.

The current limits will stay the same regardless of the voltage. So, if you're using 24 volts, you're good for 20 amps, or 480 watts, at 120 volts, 2400 watts, and at 240 volts, 4800 watts.

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For Xmas 2005, I used 2 LOR 16 channel controllers on a 240V supply. When I bought these, Dan indicated that it was possible to split the supply between the 2 banks of 8 channels; one must be 240V, but the other bank can be 24V or something else. Dan indicated that even with the lower voltage, dimming could still give unexpected results because of possible phase shifting between the low voltage (transformer effects) and the 240V supply which is used to control the dimming circuits.

As previously indicated, in 2005, I controlled using the 240 V supply only. Most circuits controlled transformer coupled lights (12, 24 and 35V). Switching was not a problem on any of these, provided the switching was not too fast for too long. For the transformers I tested, I could switch continuously at 1-2 cycles/sec with 50% on period without any noticeable transformer heating. Rapid switching eg 5c/s for short periods - 10-15 minutes, was also satisfactory. I also found no additional heating when using dimming through the transformers. This year I plan to increase the number of LOR channels, and will continue to use LOR to control the 240V supply to transformers.

Note - I did consider using the 24V supply arrangement, however, I never found an affordable 24V high wattage transformer at an affordable price. After my testing showed that switching and dimming generally worked satisfactorily through the individual transformers supplied with each Australian light set, I decided this was the better way to go.

Regards - Geoff

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