In the event of an overspeed condition, a trip relay is activated. After a unit is tripped, it requires either a reset or a power cycle to return to normal operations. Aside from the detection of an overspeed condition, things such as a loss of MPU signal, an interlock fault, or lack of a reset before the turbine is re-started could all cause a trip. Woodward ProTech 203 Overspeed Protection System Manual 85191 (B) has complete information on troubleshooting trip relays.
The three speed-sensing units in the 9905-870 model are identical. Each unit comes with its own 120 Vac/dc power supply, and they each have a separate operator interface with an LCD, touchpad, and functional status LEDs. On the LCD, operators can view the actual speed of the individual unit, and the LEDs offer a quick first-step identification of problems within a unit, such as a failed MPU or an improperly functioning CPU. Both an LED and an alarm output are used to alert operators of a tripped unit.
1 Year Warranty
