24 vdc to 12 vdc converter on a UL fire panel

[nhfire77]

Situation: Bosch D9124 combo fire burg panel. Large commercial facility. We need to add additonal 12 vdc for burg devices. There is a NAC booster that is on constant that powers duct smokes. There is a spare circuit that I can add a 24 to 12 converter on. Battery calcs are fine with adding it full load.

What do you think, Is it a problem?

 

[gadfly56]

Situation: Bosch D9124 combo fire burg panel. Large commercial facility. We need to add additonal 12 vdc for burg devices. There is a NAC booster that is on constant that powers duct smokes. There is a spare circuit that I can add a 24 to 12 converter on. Battery calcs are fine with adding it full load.

What do you think, Is it a problem?

Are you using the AUX power from the NAC booster, or planning on using one of the outputs? Are the burg devices polarized/supervised?

 

[nhfire77]

Are you using the AUX power from the NAC booster, or planning on using one of the outputs? Are the burg devices polarized/supervised?

One of the outputs, the others are already providing constant power, Which is what I need.

The devices are supervised, polarized. Keypads and motions.

 

[gadfly56]

One of the outputs, the others are already providing constant power, Which is what I need.

The devices are supervised, polarized. Keypads and motions.

The AUX power is usually constant, but the NAC outputs are usually reversing polarity. The Siemens PAD-3 has a supervisory voltage of 24VDC which flips polarity on activation. I doubt your keypad will appreciate that!

I vaugely recall that some panels use less than 24VDC for supervision (about 8-11VDC) then switch polarity and go up to full 24VDC. You could tell if you reversed the polarity of a horn because it would "moan" when the panel powered up.

 

[nhfire77]

The AUX power is usually constant, but the NAC outputs are usually reversing polarity. The Siemens PAD-3 has a supervisory voltage of 24VDC which flips polarity on activation. I doubt your keypad will appreciate that!

I vaugely recall that some panels use less than 24VDC for supervision (about 8-11VDC) then switch polarity and go up to full 24VDC. You could tell if you reversed the polarity of a horn because it would "moan" when the panel powered up.

I hear you. It is not the way we use this NAC booster. The input trigger is constant. an Octorelay will be used to cycle the power of the duct smokes, leaving the 24vdc converter constant. Actually the unit uses it aux power fed to the input. It's trouble contact is monitored by a seperate point on the system. This is how it's is described to be done in the install manual.

 

[nhfire77]

I'm looking to find out whether or not turning 24 to 12 is OK in this manner. I know it will technically work, and the devices and any trouble contacts that need supervision will have it.


It is a complicated way of doing it. The reason this needs to be done is, I discovered the system is already overdrawn and I have to add to it, to correct other issues that were discovered. I'm all bad news when I do a fire test and inspection, I find things wrong, and cost people money

I' ve never done this. I would rather seperate out the burg and fire. Problem the data line (POPEX) has both fire and burg, no one is going to pay to desire the whole building.

You know what I mean?

 

[cadpoint]

I'm looking to find out whether or not turning 24 to 12 is OK in this manner.

And why don't you call Bosch ?

 

[nhfire77]

And why don't you call Bosch ?

Have you ever been in one of their holding ques? Just kidding, good call.

 

[nhfire77]

Im scrapping the idea. I cannot fire a UL listed voltage converter for fire.

 

[MisterCMK]

I think that I have an idea for ya. PM.t