Hey all, booster pump station, 50hp motor on a VFD. Fitted a loop powered vibration sensor on the motor's drive end bearing housing, 4-20 mA, velocity, 0 to 25 mm/s RMS. It's in the PLC and on the HMI and reads about 2.1 mm removed link I verified the loop at the panel, 4.0 mA with the pump off, scaling checked.
Now nobody will give me an alarm number and I'm a bit stuck. The sensor vendor says use the ISO 10816 table. Maintenance says alarm at double whatever it reads today. The ISO table for our motor size puts 2.1 in the middle band and the next band up starts at 2.8, which seems awfully close for a pump that's perfectly happy.
What do people actually set on these? Would you really alarm at 2.8 on a pump that's sat at 2.1 since the day I fitted it?
Loop's proved, good. Does the reading change with speed? A booster pump at two setpoints won't read the same. What do you get at normal speed and at full speed, both numbers?