GE frame 7E Vibration Logic Question

I have 2 GE frame 7Es at my facility. The vibration logic in the m6b file shows that there are two setpoints for protection the “trip setpoint” normally set to 1.0 in/s and the “shutdown setpoint” normally set to 1.1 in/s.

A. Trip on Vibration is one of the highest Priority Protection. Normally the SD setpoint should be less than the Trip Setpoint.

They go for a shutdown provided The vibration levels are little higher than alarm Setpoint but below the Trip setpoint considering that reducing the Load and Speed will gradually decrease the Vibration that cause relatively less stress on the machine than the thermal shock due to trip.

If the Vibration is at MAX limits then they cannot go for SD which puts the machine at risk even Load/Speed decreases gradually. In this case the damage caused due to thermal shock is compromised than that of the damage caused due to high vibration.

I would suggest you to rasie a PAC case to the GE So that they can Suggest the Alarm, SD and Trip settings depending on the machine Frame Size. Correct Settings May reduce unnecessary trips.