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Hey guys. I work at Campbell Soup as a maintenance technician. Today, one of the flume pumps was intermittent. It would cut off at random times but start back up on it’s own. We never did pinpoint the cause of it. But, we looked at the drive parameters and the HP was set to 5. The motor HP rating was 7.5. Does this have any effect on the pump at all? Is there any suggestions you guys have that could be the problem. 3 phase motor, 480 volts. Tank before the pump must be a certain level for the pump to start running but the level was at set point. Could the transmitter for the DP cell have been giving false readings?
 

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The horsepower setting in the drive is 5 hp, but the motor is 7.5 hp?
That one's sorta obvious.
What is the rating of the drive?
Someone may had made some changes to the parameters.

New installation or is it existing and it's been running fine until now?

Anything changed recently? Motor or drive?

A drive will use the information you input into it to make various automatic adjustments.

The correct motor nameplate information must be input.
 

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Ask your programmer to set up a trend on the tank level and any other permissive for the drive like high line pressure, low inlet pressure, etc.

If you have to do it old school find the control rack and monitor the plc lights on the cards. Its easier if you can get permission to video the rack using a phone unless your banned from using a camera. Vfd's will normally surge if they are the culprit (adjusting speed to recover) rather than stopping which is more of a controls issue.

Addition: The speed of the network between the plc and hmi is slow in computer terms. Using straight code you will never notice if the tank level fails low/high for a few scans but the code will re-act and shut the drive down then it will have to stop the rotor before ramping back up to speed. There is normally a time in the program to allow for ramp so it will not set a fault. If you have flying start set it may be less noticeable.
Also check the settings for auto reset as you may have a fault that is being reset (check fault log on the drive). E.G auto reset set to 2 times at 3 seconds. Drive is shutting down for 3 seconds then ramping back up to speed may indicate a reset-able fault.
 

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Hey guys. I work at Campbell Soup as a maintenance technician. Today, one of the flume pumps was intermittent. It would cut off at random times but start back up on it’s own. We never did pinpoint the cause of it. But, we looked at the drive parameters and the HP was set to 5. The motor HP rating was 7.5. Does this have any effect on the pump at all? Is there any suggestions you guys have that could be the problem. 3 phase motor, 480 volts. Tank before the pump must be a certain level for the pump to start running but the level was at set point. Could the transmitter for the DP cell have been giving false readings?
If the drive is rated for 5HP and you connected a 7.5HP motor to it, that may have been the result of an "emergency fix" to get back up and running, then nobody followed through to replace that drive because it worked. If your pumping requirement was 5HP or under, the drive may have never known that the motor was larger, because the motor is only going to work as hard as it has to. It's also possible to program the drive to Current Limit at the drive rating, so it would never be able to get to full speed at a 7-1/2HP load, but that may have been fine for what it was being asked to do.I know people who do that on purpose.

Intermittent operation like that is usually a control circuit issue. You can look in the drive to see what it is being commanded to do and from where to see if that command is going away or not. If it's not, look at the Fault History of the drive, it should tell you if it is faulting and automatically resetting itself. If the command is what is intermittent, look into possibilities like loose wires if it is a discrete control setup, or communications problems it it is on a network. Bad shielding or a broken shield wire on control cables is another possibility.
 

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Does not the drive have a fault code register? Look up the last 10 faults.
 
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