Motor Issues?

[jahilliard]

We regularly install the electrical for Floating fountains. There are several instances when we are asked to trouble shoot existing installations so I want to have a btter understanding of these motors and motors ingeneral. This is the most current mystery:

4 - 460V 3ph 30hp motors. (2@750', 1@ 500', 1@200')
each is running at 49A under load.
Source voltage is 480V (490 Actual)
These motors will run for as much as a week and one or sometimes two will either trip the over loads in the control panel or the 60A breaker feeding the control panel. Including the shortest 200' run while the long runs are still fine.
There is #8 Cu run to each of the fountains from the lakes edge. #6 run from the source to the lakes edge.
Am I able to check for actual VD while under load? I only have access to the first 50' of the run to the motor. Is the Voltage consistent the entire length?
I do understand the #8 is maxed out when considering VD recomendations but why would the issue be so inconsistent? The cable and conductors are run under water and underground.

Looking for some insight on troubleshooting motors, how to check actual VD under load, and any recommendations for these type installations. I am sure you'll have questions and I will try to respond in a reasonable amount of time.

 

[ptonsparky]

A 60 amp breaker is too small for even one of the motors.
Meg the entire installation.
Do a thermal scan of the starters and breakers or do a FOP across each.
Don your PPE and take a voltage reading while the motors are in operation. Newer meters are available to do this while the doors are closed and you are out of danger.

add:
What are the overload settings?
Are the starters in full sun?
Bimetal, melting alloy or electronic overloads?

 

[jahilliard]

Each motor is individually Fed. There is a 60A 3P breaker for each of the 4 going to a Control Panel for each motor with 60A breaker for the Motor Starter, Time Clock, Over Loads etc. The breakers have only tripped about 50% of the time, the OL's have tripped the other and they are adjustable set to 55A, are resetable. Yes they are in the sun indirectly. To be clear each motor has it's own independent control panel.

 

[jahilliard]

I am also able to check the voltage while under load at the in ground junction box that is approx. 50' from the source. I installed insulated lugs to be able to check voltage and there and I didn't observe an unusual drop in voltage at all. Would the voltage be the same there as it would be at the motor. What I did notice is that the Control Panel Manufacturer had #8 Aluminum from the load side of the starter to the terminal block (one terminal block had actually melted) so we eliminated that and terminated the #6 directly to the Starter.

 

[just the cowboy]

In the sun

In the sun

You need to check the thermal overload type, the bimetal and soldier pot type can be affected by temperature. Keep a log of when they trip, what was temperature and what was cloud cover.

 

[Jraef]

Floating fountains? Any possibility that plants or sticks (or animals) are getting sucked into the pumps and jamming them? It could be that after jamming and tripping, the flotsam is getting chopped up when the pump gets restarted so you don't see it. Depending on the type of pump (positive displacement for example), a simple flow restriction might even cause an overload even if not completely blocking it. If they are centrifugal pumps, excess flow from a broken pipe or valve might be causing an overload. I worked on the dancing fountains at the Bellagio in Vegas, one of the pumps kept overloading only during a particular part of the performance. Turned out to be a pipe that had broken off of a valve that only came on during that sequence. When the pump had to feed that broken pipe, the open channel flow cause the pump to overload.

Adjustable overloads leaves out the possibility of melting alloy type, but if they are Solid State or IEC bimetal overloads, they might trip on phase loss or a severe phase current imbalance. That could be from a severe voltage imbalance caused by something up stream that is seemingly unrelated, or as Tom said, problems in the contactors, breakers, feeder etc.

And I too agree, a 60A breaker is likely too small for a pump rated at 55A. The OL relay is there to protect the motor and wires, the breaker only provides Short Circuit protection and can be as high as 250% of the motor FLA. If it is a factory built combo starter with Mag-Only breakers rated 60A, that's different, but then you may have the mag trips set too low. They could be set for 600A or more.

 

[don_resqcapt19]

I would be looking at the possibility of too much flow...the NEC FLA for that motor is only 40 amps and that is typically higher than a real world motor.

 

[jahilliard]

All of those are actual possibilities...vegetation, etc. As far as the actual FLA of 49A's and the voltage being where it should be..."too much flow" could be from too much resistance (water flow or back pressure) somewhere? I do know that the fountain contractor adjusted the fountain head and the amperage dropped a few amps. According to the manufacturer (Shakti) the motor is rated at 53A's. We have experienced issues with these Shakti motors in the recent past. As many as 20 or more in the past 2 years have gone bad within a year. I believe it is from the Caps in the Control panels... I don't know enough to completely understand why..but If someone uses a Franklin starter on other motor types it can cause problems over time. I believe the Microfards in the caps can play a role in damaging the motor. Can anyone recommend somwhere that I can reference this type of information to get a better understanding?

 

[ptonsparky]

Assuming this is a typical submersible centrifugal motor, increasing the flow increases the amperage. Restricting the flow at either the input or output will decrease the amperage.

What type of capacitors do you have at the control panel? Power factor correction?

PFC wil reduce the amperage from the point of attachment to the source.
Make sure you are taking the amp reading of the motor correctly and also setting the overloads as corrected.

 

[Jraef]

All of those are actual possibilities...vegetation, etc. As far as the actual FLA of 49A's and the voltage being where it should be..."too much flow" could be from too much resistance (water flow or back pressure) somewhere? I do know that the fountain contractor adjusted the fountain head and the amperage dropped a few amps. According to the manufacturer (Shakti) the motor is rated at 53A's. We have experienced issues with these Shakti motors in the recent past. As many as 20 or more in the past 2 years have gone bad within a year. I believe it is from the Caps in the Control panels... I don't know enough to completely understand why..but If someone uses a Franklin starter on other motor types it can cause problems over time. I believe the Microfards in the caps can play a role in damaging the motor. Can anyone recommend somwhere that I can reference this type of information to get a better understanding?

Shak·ti
ˈSHəktē/
noun Hinduism
noun: Shakti; noun: Sakti

the female principle of divine energy, especially when personified as the supreme deity.

Eh?

53A on a motor called 30HP?
Capacitors in a control panel on a 3 phase motor? Are you feeding these with single phase power or something? or are they Power factor Correction capacitors? If so, are they even necessary for a motor that is loaded to that level?
What the heck are these things?

 

[topgone]

Eh?

53A on a motor called 30HP?
Capacitors in a control panel on a 3 phase motor? Are you feeding these with single phase power or something? or are they Power factor Correction capacitors? If so, are they even necessary for a motor that is loaded to that level?
What the heck are these things?

Methinks the motor is actually 30 kW (40HP).

 

[ptonsparky]

Methinks the motor is actually 30 kW (40HP).

Ouch. That would be a design issue.

 

[JFletcher]

If the pumps cavitate then reprime suddenly (clear the air bubbes), the amperage could spike high enough to trip the breaker or OL. Have intermittent short circuits been ruled out?

 

[tom baker]

I agree with Don and Jref. The motor overload may be doing its job. Its tripping due to load.
A wastewater electrician I worked with once told me, the mechanics say "its always an electrical problem" when its typically a plugged pump, bad bearing, or something that is binding up the motor.
Do you have access to a data logger to log the current?
Double check you have the correct size overloads, are they quick trip ambient compensated for submersible pumps?
And if VFDs, the overloads are part of the programming, and those have to set correctly, with voltage, service factor, etc...

 

[Jraef]

Methinks the motor is actually 30 kW (40HP).

You know, that makes a LOT more sense. :thumbsup:

I still want to know what the capacitors are all about though.

 

[ptonsparky]

You know, that makes a LOT more sense. :thumbsup:

I still want to know what the capacitors are all about though.

Here, for our POCO, we are supposed to have PFC, no matter .97 or .56. Penalties apply. 10hp & up.

 

[ActionDave]

..."too much flow" could be from too much resistance (water flow or back pressure) somewhere?

Just the opposite. More back pressure means less water is being moved so the motor is doing less work. If you were to close off the outlet you would be close to no load amps.

... I believe it is from the Caps in the Control panels... I don't know enough to completely understand why..but If someone uses a Franklin starter on other motor types it can cause problems over time. I believe the Microfards in the caps can play a role in damaging the motor. Can anyone recommend somwhere that I can reference this type of information to get a better understanding?

This makes no sense. Either there is a misunderstanding, misapplication of equipment, or bad information being given.

 

[jahilliard]

Ok, mindless mistake on my part...no caps in the control panel. That's typically for the 1ph motors of course. and...I absolutley believe you are right as far as the motors being 30KW - 40Hp! I am being lied to about the motor size and being blamed for the issues, this business is a soap opera with the fountain companies, and things like this are never their fault! I want to pull the motor out of the water and verify that but that would be one heck of a project, these things are huge and weight a ton, but I'll do it ina second if this guy keeps pushing! I greatly appreciate the feedback...and I plan to educate myself MUCH more on motors!! Thank you!!!

 

[ActionDave]

... I am being lied to about the motor size and being blamed for the issues, this business is a soap opera with the fountain companies, and things like this are never their fault! I want to pull the motor out of the water and verify that but that would be one heck of a project, these things are huge and weight a ton, but I'll do it ina second if this guy keeps pushing! I greatly appreciate the feedback...and I plan to educate myself MUCH more on motors!! Thank you!!!

You gotta get some solid info on the rating of the motors. In the meantime you might be able to lower the amps enough that you won't be tripping the breaker by restricting the flow.

 

[jahilliard]

Yea I know, solid info seems to be the initial problem with this entire scenario. But, based upon the info that I do have...460V (480+ actual) 3ph "30Hp" motor running at 49-50A, with a "53A rating"...just seems a little obvious what's really in place. These floating fountains really don't max out the motors when they are running...I can't imagine a 30Hp motor being able to run at 50 Amps continuous. Any ideas??