Thyristor Health Monitoring system
Several
banks of thyristors are used in very high voltage applications. In such applications
it is desired to get an alarm if one of the devices in a bank has failed [the system
can still function] while it is required to
get a trip O/P if more than one devices
in the bank has failed.
The thyristors are monitored for health condition by sensing the flow of gate current.
Because of high voltages and interferences involved, one cannot think of drawing
copper cables out of the control panel where these devices are housed. Instead it
is required to sense the presence of gate current by looking at an LED indicator
already available in the gate circuit. This requirement made us develop an annunciation
system including the optical fiber cable to carry the light of the LED out of the
control panel. Thus carried light is sensed and the required alarm outputs are derived
along with indicators to show faulty devices.
IR Bulb Failure Annunciator
In certain applications like semiconductor wafer
fabrications, infrared bulbs [IR bulbs] are heavily used. There will be too many
rejections if these bulbs fail during the process. It is required to have a system which will immediately
sense fusing of these bulbs and give alarm without waiting for the temperature to
fall. This is exactly like Heater Failure Annunciator with slight modification and
tuning.
