R
I have a query to experts of this forum:
We have Fire Detection System for our Gas Turbines. The detectors are thermal detectors which "close" at high temperatures (indicating fire). They are otherwise open. There is +ve power (62.5VDC) on one side of the thermal sensor. The coil of CO2 release SOV is connected to the other side of the Thermal Detector. The second end of coil is at -ve part voltage (-62.5VDC).
In this configuration, during the normal condition the SOV is de-energised (as because the Thermal Detector is open) and CO2 is not released. In case of Fire the temp is expected to rise and at the set temp value the Thermal Detector will close and energise the SOV to release the CO2.
Is this concept of energising the SOV to release the CO2 safe? Usually most trip coils remain normally energised to keep the equipments running. And this seems to be a safe practice as well because in case of a coil failure or power supply wires coming out of TBs the Trip coil will de-energise and prevent the equipement from running. Should there be a similar approach for the CO2 release SOV coil as well? Should it not be kept normally energised so that any failure of coil or power supply cables would de-energize the SOV and result in a trip. This can be a loss in terms of inadvertant CO2 relase, ofcourse, but wouldnt it be better than a condition when fire really happens and its discovered that the SOV coil was open or the power supply cable was open? What are the indusry standards governing Fire Logics.
Thank you
Regards
Ritika
We have Fire Detection System for our Gas Turbines. The detectors are thermal detectors which "close" at high temperatures (indicating fire). They are otherwise open. There is +ve power (62.5VDC) on one side of the thermal sensor. The coil of CO2 release SOV is connected to the other side of the Thermal Detector. The second end of coil is at -ve part voltage (-62.5VDC).
In this configuration, during the normal condition the SOV is de-energised (as because the Thermal Detector is open) and CO2 is not released. In case of Fire the temp is expected to rise and at the set temp value the Thermal Detector will close and energise the SOV to release the CO2.
Is this concept of energising the SOV to release the CO2 safe? Usually most trip coils remain normally energised to keep the equipments running. And this seems to be a safe practice as well because in case of a coil failure or power supply wires coming out of TBs the Trip coil will de-energise and prevent the equipement from running. Should there be a similar approach for the CO2 release SOV coil as well? Should it not be kept normally energised so that any failure of coil or power supply cables would de-energize the SOV and result in a trip. This can be a loss in terms of inadvertant CO2 relase, ofcourse, but wouldnt it be better than a condition when fire really happens and its discovered that the SOV coil was open or the power supply cable was open? What are the indusry standards governing Fire Logics.
Thank you
Regards
Ritika