I have a old Mark V which has UV-Tube flame detectors powered by 335VDC from the PTBA term. board in the Mark V. I need to remove the existing 335VDC to the PTBA terminal and replace with existing 24vdc power from the Mark V (was told that the exiting unit has a 24vdc with 1 amp output). New flame detectors require 24vdc. Did not want to install an additional transformer in the cabinet.

This is the first Mark V that I have worked with and sure could use some help.

Cordially,
Larry

 

Larry,

It can't be done. The Mark V was designed for use with Geiger-Mueller UV flame detectors which must be connected to the <P> PTBA and which require 335 VDC to operate and which produce a frequency proportional to flame intensity.

When GE wanted to use 4-20 mA Flame Trakkers it was necessary for the manufacturer (Reuter-Stokes) to develop an interface module--which used 24 VDC on the low-voltage side and converted the mA signal to an isolated frequency that was connected to the PTBA in place of the Geiger-Mueller flame detectors.

The Mark V needs to see a frequency that is zero-based that is proportional to flame strength and which must be connected to the <P> PTBA. All of the flame detection logic is based on frequency, not voltage or current. And because the Mark V uses 335 VDC as the "source" for the frequency the flame detection signal must be capable of switching 335 VDC at a frequency proportional to flame intensity.

There might be other ways to do the flame detection using a 4-20 mA signal in sequencing but there will be a latency in flame detection and the built-in flame detection capabilities of the Mark V couldn't be used. It would be akin to playing with fire with the flame detection--which would be difficult to explain to an insurance company or a court should something unanticipated occur.

Best to find a way to use the existing capability/requirement--which is going to require an interface, though that interface could indeed be powered by 24 VDC from the Mark V, just like the Reuter-Stokes.

Cordially yours, as ever,

CSA

 

thanks for the reply. I have found an existing 24vdc power coming from the TBQG card on the P core that I can use to power up the new flame scanners. New scanners are from BFI Automation, they will provide the pulse output that the Mark V requires. If your interested I can send you the cutsheets for the interface.

My email is Larry.drake_Huntsman.com
thanks again for the reply,
Cordially,
Larry Drake

 

Larry Drake,

How about a link to the proper .pdf file on the BFI Automation website for the Mark V-compatible flame scanner? That way anyone can download the cut-sheet at any time!

Thanks,