Phase monitoring

[hockeyoligist2]

Is there anything on the market that could detect the loss of a phase down stream? Here is the situation. We have floating aerators (sewer plants) with SO cord from the disconnect to the aerators. Phase monitors in the box with the starters, which only monitors the incoming power. But, the SO cords wear from the movement of the aerators and eventually they will wear one or more of the wires in two. Very often the motors burn out before the overloads on the starters trip. Yes, in case anyone asks, we have them set correctly! They are mostly 40 hp motors so it's not a cheap rewind or replace! Plus a high $ Crane to lift them out. The "powers that be" are tightening up the budget and want answers, even though this has been a problem for 50 years......

If I can't find anything..... I'll probably have to start going out in a Jon boat ( 300 lb capacity and I weigh 250, plus tools) every two weeks and visually inspecting the SO cord! We have about 80, scattered around different plants.. HELP!!!!!!!!! LOL

 

[jtester]

Could you do it with current monitors? If one phase experienced a sudden drop in current, you'd probably have lost a phase. You could actually trip for any significant current imbalance, and catch a motor in the process of failing as well.

Jim T

 

[eric stromberg]

There are many solutions. The real issue is deciding which route you want to take. Google "Phase loss monitor," and you will find relays that can be installed that will shut the motor down on the loss of a phase. Google "Electrical disturbance analyzer," or a variant thereof and you will find analyzers that can be connected to the circuits that can alarm on changed conditions.

If you want to simply go around and check, you can buy a power quality meter that will show you the three phase waveforms.

What type of equipment feeds these motors? A Motor Control Center? There might be enough room in the buckets to install power monitors.

Is there a process computer that controls all of this? Are there enough available inputs to connect an alarm from the power monitors to the process computer?

 

[hockeyoligist2]

Eric, It is fed from an MCC. But it just has a breaker in the MCC, the individual aerators have a disconnect with starters, breaker, and a phase monitor located around the ponds. Can't remember the name on the phase monitor (8 pin plug in), but if you lose a phase or POCO has a problem and switches a phase it shuts them down. There is nothing to monitor a phase loss After the starter. They are not computer controlled. Just and on-off switch. Its just simple, outdated, equipment.

If it is expensive they won't go for it. And anything that I put in has to be durable. The sun on the SS boxes (during the summer we have a lot of nuisance trips just from the heat buildup in the boxes), and the gasses that are put off by the sewer eats things alive! Lot of green copper!

 

[ptonsparky]

www.Symcom.com They have about everything you need for this application. I am sure there are others.

 

[catchtwentytwo]

Go to this page TimeMark and on Application drill down to Phase loss Protection. Should cost a lot less than that 40 HP change-out.

 

[LawnGuyLandSparky]

If these run 24/7, you can predict the average lifespan, and just schedule automatic replacement of the SO cable at regular intervals.

They replace lightbulbs in traffic signals and on streetlights on a regular schedule. Rarely are any burned out upon replacement.