Single Phasing in Electric Motors

Causes and Solutions to Protect your Motor

I once had a customer ask me for some advice to help them come up with some ideas as to why their pump would trip as soon as it was lowered into slurry.

I asked questions such as:

  1. Have you checked for proper rotation?
  2. Did you check for pluggage in the discharge line?

After verifying these things, the pump still did not perform. It would trip on overloads as soon as slurry was introduced. I then asked for amp draws but unfortunately got no response.

By chance, I was due onsite at that particular plant the next week so I decided to investigate for myself what may be causing this particular pump to trip. After investigating, we found that the pump was single phasing. This would trip the pump once it is put under a load. This is a common problem so let’s take a look at what single phasing is and some of the causes associated.

Single phasing simply means that one of the line connections of a motor is not connected, resulting in the motor running on a single phase. A single-phase condition subjects the motor to an excessive voltage imbalance, often meaning high currents and motor heating. Induction motors designed to run from a single phase use a start or run capacitor to assure that the motor starts and runs in the correct direction. 3-phase motors rely on the phase sequence of the power supply to assure they start and determine their rotation, so with only two lines connected, it is uncertain if a motor will start and what direction it will rotate if it does.

If a single-phasing motor does start, it may run under light loading conditions without tripping simple overload breakers or fuses. When the motor’s load is increased, the current may increase well beyond the motors full load current or the rotor may lock altogether. Both will trip correctly sized motor protection well before the pump achieves the performance you would expect.

Some of the causes of single phasing are:

  1. Damaged motor starter contacts
  2. Open fuse or open pole in circuit breaker
  3. Open cable caused by overheated or damaged connecting lug.
  4. Open connection in wiring.
  5. Open winding in motor

If you feel that you may be operating under single phase conditions make sure to start by checking the amperage across all 3 phases. You will notice a significant difference in amperage on one of the 3 legs if this is the case. Always have a qualified electrician investigate all conditions and connections.

Motors can be expensive. It is best to provide proper safety precautions to protect your motor against single phase conditions.

Learn about the industrial pumps that Hevvy Pumps has to offer for your project:

 

Read the Slurry Pump Maintenance Guide to learn how to maintain your slurry pump for optimal performance. View slurry pumps options.

Talk to Hevvy Pumps for more information.

Travel Safe,

Jerry Morrow

Ghost in the Pump

Pumping Industry Solutions

I received a call from a customer that one of our new pumps was acting up. The pump would quit pumping and then all of a sudden start again.

They pulled the trouble pump out of service, replaced it with a spare, and asked me to come on site to perform an inspection.

I arrived onsite and with the help of customer’s millwrights we disassembled the wet end of the pump. Everything looked great and the shaft turned freely by hand. As people started coming by to see what we had found, I started asking questions. After a minor interrogation I found out the pump was sitting directly over an air sparger. The pump seemed to pump fine in the day time but would quit pumping at night. I asked how the air was controlled going to the sparger and found out there was a manual valve? I then asked the operations superintendent about taking me to the location of the pump. They didn’t understand why I wanted to go but I explained that I wanted to try and create similar conditions in the spare pump to see if we could find the problem. With a puzzled look on their faces, they finally agreed to take me.

When we got there I asked where the manual air valve was located. With myself operating the valve I asked several employees to watch the pump and inform me of what was happening. The valve was barely open supplying a minimal amount of air to the sparger. As I opened the valve they informed me the pump quit pumping. I started closing the valve and it started back again. I repeated the exercise once again with the same results.

The operations team was relieved that the ghost had been found.

It seems that someone at night was opening the valve to get more circulation in the tank. The air was shooting straight up into the wet end of the pump causing an air lock or too much air entrainment in the slurry for the pump to handle. There is a maximum amount of air entrainment allowed in slurry or it cannot be pumped. The wet end and/or piping can also become air locked which will stop all pumping action in the system. At shift change the valve was regulated to its normal position and the pump would start back up.

We recommended to the customer to either change the location of the air sparger or install a diverter plate to deflect the air from going straight into the pump. Thankfully there has been no issues since.

Learn about the industrial pumps that Hevvy Pumps has to offer your project:

 

Read the Slurry pump maintenance guide to learn how to maintain your slurry pump for optimal performance. View slurry pumps options.

Talk to Hevvy Pumps for more information.

I thought the above photo was suiting to this blog. The clouds add a touch of beauty and eeriness to the mountains, don’t they?

Travel Safe!

Jerry Morrow

Grease the Bearings

Put Bearing Misconceptions to Rest

One of the most common failures that I encounter in my travels is customers often times do not grease the bearings in our vertical series of pumps. Because of this, most of our pump failures involve the lower bearing.

Customers will often grease the upper bearings assuming the grease makes its way down to the lower bearing. This is a false assumption as there is a huge cavity in between the bearings. There is a grease zert found near the baseplate for the bottom bearing. If this bearing is not greased the pump will soon lock up and if not caught in time can cause serious damage to the bearing housing.

The proper grease to be used can be found in the manual provided with the pump. The amount of grease can be determined by using a formula written by SKF, a well-known bearing supplier:

                 G = (D x B) / 10 

        
            G– Amount of grease in ounces

            D– Outer diameter of bearing in inches

            B– Bearing width in inches

Calculating greasing intervals is a bit more complex. It is based on temperature, speed of the equipment, hours in operation per week, and the type of bearing used. There are formulas on the SKF website for calculating the greasing interval.  SKF Grease Interval 

Learn about the industrial pumps that Hevvy Pumps has to offer your project:

Read the Slurry pump maintenance guide to learn how to maintain your slurry pump for optimal performance.

Talk to Hevvy Pumps now for more information

Above I have included a picture I took at Lewis Falls, Yellowstone Park during a stay in Wyoming. If you ever get a chance to visit Yellowstone Park, I highly recommend planning a time to see the falls in person!

Travel Safe.

Jerry Morrow

Quelles sont les pompes les plus adaptées aux puits de cokéfaction retardée?

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Approfondissez vos connaissances sur nos pompes et l’industrie

Le pompage de l’eau, chargée en particules fines de coke, produite par le jet de découpe à l’eau de l’unité de cokéfaction retardée (DCU) est une application difficile. Dans cette situation, les pompes tombent généralement en panne, ou voient leur durée de vie réduite, pour un grand nombre de raisons, notamment : la forte charge en fines, les conditions d’aspiration difficiles, les températures élevées et la profondeur des puisards. Tous ces facteurs contribuent à créer un environnement difficile qui augmente le nombre de pannes et envoie les pompes à l’atelier.

Cette application nécessite des pompes de relever les défis suivants:

• Lubrification du palier de l’arbre de transmission en raison des températures élevées et à l’entrée de matières solides.
• L’effondrement des matières solides accumulées qui peuvent obstruer l’extrémité d’admission de la pompe et étouffer l’aspiration avec des particules solides.
• La rupture du joint et du palier inférieur en raison de la cavitation provoquée par les températures élevées et entraînant une charge nette absolue à l’aspiration faible, ainsi que l’obstruction de l’orifice d’aspiration en raison de l’accumulation de matière solide.
• La rupture du joint et du palier inférieur en raison de l’obstruction par les fines, ainsi que l’inversion du flux et la possible rotation en sens inverse provoquées par des clapets antiretour défectueux.
• La surchauffe des moteurs submersibles.

Le nouveau modèle submersible HNS de Hevvy-Toyo répond à chacune de ces préoccupations.

Par conception, nos pompes HNS submersibles ne comportent pas de palier d’arbre de transmission, source principale de défaillance des pompes verticales. La suppression de ces roulements signifie qu’il n’y a pas lieu de s’inquiéter de problèmes de lubrification, de la pénétration de matières solides dans le palier inférieur ou du blocage de l’arbre provoqué par les différences de température entre la colonne de palier et le tuyau de refoulement. Les paliers de l’arbre de transmission sont simplement inutiles!

Notre système breveté Plenum 54™ associé à notre joint exclusif XD sont spécifiquement conçus pour fonctionner dans des environnements à haute teneur en matières solides et en fines, dans des conditions d’aspiration intensives où la cavitation est courante et où la pompe et l’ensemble rotatif peuvent être soumis à une charge importante en raison de la forte teneur en particules solides ou d’importantes fluctuations des conditions d’exploitation.

Afin d’offrir des solutions à ces problèmes, les modèles HNS de Hevvy sont livrés avec notre agitateur breveté et son jet annulaire. Ces éléments essentiels permettent de garder la zone en dessous et autour de la zone d’aspiration de la pompe à l’abri des particules solides, tout en fluidifiant ces particules en cas d’effondrement d’une « masse » de matière sur la pompe.  Lors de la réinstallation de la pompe, le puissant jet annulaire permet également de dégager un chemin vers le fond du puisard à travers les particules solides accumulées en son absence. Le jet annulaire associé à la configuration submersible constitue une solution efficace face aux défis que doivent relever les pompes verticales. 

Donc, comment installer une pompe verticale au fond d’un puisard qui est bien moins profond qu’au moment où cette pompe a été retirée?  Avec le modèle HNS submersible et son jet annulaire, ce problème est simplement résolu.

Au cœur de ce système se trouvent le moteur HNS et l’ensemble rotatif.  Conçu avec un rapport L/D < 1 (notre technologie brevetée « pompage à sec ») et construit de façon modulaire, le modèle HNS offre une grande sécurité pour les applications les plus exigeantes ainsi que la souplesse nécessaire aux évolutions.   Le concept modulaire présente plusieurs avantages:

• Spécifiez votre propre coefficient de service : 1.35, 1.5, 2.0, 3.0 ?   Les extrémités d’admission sont interchangeables pour une grande variété de moteurs, vous permettant ainsi de personnaliser votre coefficient de service.  Que vous souhaitiez « surcharger » votre ensemble rotatif, ou réduire les charges internes et les temps de fonctionnement, la conception modulaire de HNS vous le permet.
• Le modèle HNS est interchangeable avec tous nos modèles d’extrémités d’admission.  Si les conditions d’exploitation changent ou si vous souhaitez utiliser la pompe pour une autre application, la conception des modèles HNS vous permet d’échanger l’extrémité d’admission ou le moteur pour répondre à vos nouvelles exigences.

Le modèle HNS peut également être fixé à une colonne et à une plaque de montage dans une configuration pseudo-VS4 pour modifier les pompes problématiques existantes, tout en maintenant la configuration actuelle de la tuyauterie.

Que vous ayez besoin d’une pompe submersible ou verticale pour votre puisard à coke, Hevvy/Toyo possède les connaissances et les solutions disponibles pour vous assurer fiabilité et longévité. 

Parlez à l’un de nos experts en coke pour savoir comment nous pouvons vous aider à améliorer la fiabilité de vos pompes de puisard de décokage.

Pump making strange noises? – Check the belts

I recently visited a well-known copper mine that had contacted us after hearing some irregular noises coming from their brand new pump. The noises were obviously causing them some panic, especially with it being from a new pump. They were convinced the sounds were being caused by either a bearing issue or the impeller rubbing.

After arriving on site, we started up the pump again and that noise they had mentioned over the phone was very much alive and present, but after years of experience listening to equipment I was not convinced it was the impeller or the bearings. There was no knocking or rubbing sounds like you would hear if it were the impeller. The bearings weren’t making any unusual noises such as grinding and their temperatures were normal. If the bearing temperatures are in the 160-180 degrees Fahrenheit range, then it’s safe to say you likely don’t have a bearing issue.

I asked them to remove the belt guard and check the tension on the belts. (This is where I will note that the factory typically does not ship pumps with belts and sheaves installed, as was the case here. The customer was sent these items as part of the shipment and they were installed on site by the customer).

When we checked the tension of the belts on site, sure enough the belts were slack. I asked them to tighten the belts, put the belt guard back on and try again. The noise was gone and the pump has been running great ever since.

This story is a great reminder to us all. First of all, it is good policy to check the tension on your belts every 3-4 months. New belts will stretch as they run and will need to be adjusted frequently to ensure proper tension. Secondly, as was the case with this customer, noises can be caused by many factors on a pump. Sometimes if you are unsure and before spending lots of money renting equipment like cranes to lift a pump out of a sump or putting yourself through a costly downtime situation while you chase a mysterious problem, start from the top (at the belts). It could save you a ton of cash. The tool I use to measure the tension of belts is called a Gates Belt Tension gauge/tool. It comes with a paper that has a formula and chart as to how much tension should be on the belt.

Learn about the industrial pumps that Hevvy Pumps has to offer for your project:

 

Read the Slurry Pump Maintenance Guide to learn how to maintain your slurry pump for optimal performance. View slurry pumps options.

Talk to Hevvy Pumps for more information.

If you have a pump problem you’d like me to weigh in on or any questions, I’d love to hear them. If you want me to come and check out a pump issue you’re having on site – feel free to call or email.

As promised, I’ve included one of my favorite photos while travelling in Utah above.


Travel safe!
 

Jerry Morrow

Service Adventurer

Thanks for checking out my blog. This is literally going to be a diary of the life and times of a Field Service Manager.

First a joke…
What do you call a man constantly in the dog house with his wife?
A field service manager.

Okay, all joking aside, this blog is for every maintenance manager and superintendent out there, as well as anyone else who just wants to know something about how to take care of their pumps. 
I’m going to write about the calls that I make; the typical problems with equipment and systems that I face. How to provide gold standard pump preventative maintenance so that you get the longest life out of your process equipment. How to deal with some of the classic cases of vibration, overheated bearings, teardowns, seal failure, cavitation, slurry pump maintenance guide, and, etc.


I’ll also keep it light, giving you some amazing pics of my travels (check out the one at the beginning of my blog – this one I took while traveling in Canada) and reports on the accommodations I stay at. You can only imagine some of the situations I find myself in.

Learn more about the variety of industrial pumps that Hevvy Pumps offers, including:

I love my job. I get to provide knowledge and hands on solutions to our customers. If you have a problem with your pump, give me a call anytime.

Thank you for subscribing.

Jerry Morrow