Motor problem

[puckman]

This is going to be a hard question to answer, but going to ask it anyway. This on a 200 hp pump/motor for a wetwell. It is tied into a anunciator . It starts and runs in hand position fine, when it is put in auto it goes into malfunction on the anunciator. Now the motor has stator rtd's, bearing rtd's, heater,thermostat , oil switch and more then we have the vfd . Any ideas on something like this ? Would you start on the motor safetys first? or the controll panel ? timing relays, cr and more. There are 2 pumps / motors and each use the same auto controlls when either one is in the lead and the other motor works fine. No vfd , motor ol , or any light lights up to indicate a problem. Thanks for any tips

 

[charlie k.]

Are the controls and lockouts fail safe? Does the problem occur when the VFDs are powered down? Is this a new installation or existing? If it is existing has it ever worked correctly?. More answers are needed to come up to the solution. Fail safe controls sound like the issue.



Charlie

 

[realolman]

You're right about it being hard to answer .

What does the annunciator say it doesn't like?

We had one that went off on errors that were way too short lived. The annunciator should not have been going off. The errors should have been lasting longer before the annunciator went off. About the third annunciator replacement cured the problem.

Can you run it on hand and verify the readings of the connected sensors?
How much trouble is it to swap annunciators to see if the problem stays with the pump or travels with the annunciator?

 

[rcwilson]

There are 2 pumps / motors and each use the same auto controlls when either one is in the lead and the other motor works fine.

Please clarify- When one motor #1 is in lead and in auto, does motor #1 work correctly? Same with motor #2? When motor #1 is lead does motor #2 work correctly in the lag position and vice versa?

Since the motor works in manual, it probalby isn't the start-stop controls, the vfd or the RTD's or oil pressure. Could something in the lead/lag auto circuit logic be warning that the lag pump is not ready to operate?

 

[puckman]

We have change the board in annunciator for pump and it [annunciator] still goes right off. We had 2 spare slots we used. The bad motor controller was no1 and was in an alarm on auto and operater switch pumps and this one has not caused any problems. Both units are only about 3 yrs. old. It doesn't matter which one is 1 or two as soon as the hoa switch is put into auto [1to2 seconds] the annunciator goes into alarm.
If I can get anymore info I will put on the board. Thanks again for the help.
Forgot I found the board in the annunciator for the pump had a small burn mark on a track and replaced the board with each of the 2 spare boards but didn't help.

 

[Jraef]

Problems such as this are usually logic related. Whatever the annunciator is communicating to is providing a signal when in "auto" that is not really representative of conditions in the motor/drive system. I find this is usually a timing problem, i.e. when in auto, some sort of control logic is delayed in making the pump get to a specific output that is being monitored by the annunciator, so the alarm goes off. When you put it in hand, that delay in the automation system is not there, thus no problem.

Beyond that generality it is impossible to trouble shoot this through the filter of a keyboard and DSL connection. You need someone experienced in control system trouble shooting to look at everything involved.

Always move from what you know to what you don't know.