I have gas turbine frame5. We have commissioned new CO2 system for fire protection in replace of Halon system. but I want to know that when fire will come in turbine compartment, accessories comp & load gear comp then how will sense the fire in MARK-VIE controller. And what is sequence of fire detector actuation.

Also I want info about working principle of fenwell fire detector.

 

It's not about fenwell fire detector, but you should refer to logic that implemented on fire&gas panel, i believe "the GasTurbine manufacture" supply this document

For fire (heat rise) detector, which i remember it should be 2oo4, meaning when only sensor not healthy it will generate alarm, and if two sensors not healthy then generate trip to GT

 

If a new CO2 system was commissioned, then it should have been tested to ensure the Mark VIe receives a signal that a fire has been detected, and usually a signal that CO2 has been discharged. That would seem fundamental to the commissioning of such a critical system.

I believe many Mark VIe systems use a contact output from the fire detection and -discharge system as a contact input to intitiate a turbine trip, and in many cases to also shut down pumps and fans in advance of the discharge of CO2. I've been told that some Mark VIe systems have this contact connected to an input on the TREG terminal board, while some connect it to a discrete input terminal board (TBCI or TDBT or TICI, usually).

We can't know how your Mark VIe is configured nor how the fire detection and -discharge system is connected to the Mark VIe. You will need to review the configuration of the Mark VIe at your site to make that specific determination.

Most Fenwal fire detectors are sophisticated heat "switches" that operate both on a rate-of-rise principle as well as a setpoint. The concept is that if there is a fire the temperature will usually increase very quickly (the rate of temperature rise will be very fast), and the Fenwal detectors can detect this and change state to indicate the presence of a fire. In some instances, the rate of temperature rise may not be as fast but the magnitude of the temperature rise can be much higher than the ambient locale. In this case, the Fenwal will sense a high temperature and change state to indicate the presence of a fire. So, the unique feature of most Fenwal fire detectors is that they can detect both an excessive rate of temperature increase, acting very quickly to indicate the presence of a fire, or they can detect an excessive temperature to indicate the presence of a fire.

As for the two-out-of-four (2oo4) business, that depends on how the packager of the fire detection system chooses to provide some level of redundancy to try to prevent nuisance trips and discharges. There are all manner of redundant, and even non-redundant, fire detection schemes for GE-design heavy duty gas turbines, some which only employ Fenwal or similar heat detectors, some which only use infrared detectors, some which use a combination of the two, and even some which also use smoke detectors.