text: <s>[INST] 1339 PLUSII Summary: Erratic frequency response on start-up accel rampWe're having a problem with an older drive starting a pump in auto when commanded to do so from the plc. On start-up it will trip and give us an alarm code 06 Motor Stall Fault. The description for the fault states that the current stayed above the [Current Limit} setting for more than 4 seconds. So I did some investigating with a 1730 Fluke Energy Logger because it can measure all three phases for volts, amps, hertz, KKw Kvar, etc... I also did some digging around through the settings. The Accel time was set for 17 seconds. The Motor NP fla is 285 Motor np volts is 460 RPM 1785 HP 250 I recorded the motor running from start up for 22 hours and the results surprised me. During the start-up acceleration to speed the frequency was very jumpy. There is a huge spike in frequency when the motor starts and it doesn't settle down until well after the accel time is over. Every time the frequency adjusts there are several spikes in the direction of the change. and the average volts/hertz ratio is 8.1343 (average of 6 measurements taken during acceleration). So my question is which is the most likely culprit, the main control board, the gate driver board, or the isolation board? Which should I check second? Which should I check last? Regards [/INST] Can you use DriveExecutive to trend commanded speed speed and feedback speed (if available)? Comparing the drive's commanded speed to the chart you have now from the fluke meter would provide some insight. Your chart makes it look like your set speed is 55Hz. The 17 second ramp gets you to 52.75hz, and then the drive takes another two minutes to get to 55 hz. The spikes you refer to are about .75hz in amplitude, and it looks like they last for about 5-10 seconds each. Can you describe the load this motor turns? Is it high inertia? How does the drive control the motor: V/hz, sensorless vector, closed loop vector? \\n </s>