# Calculating Minimum Cooling Flows

Electric motors convert electrical energy into mechanical energy, making it possible to move things, like water. In the process, electric motors produce heat, and that heat must be displaced. Otherwise, the heat will build up in the motor and cause motor failure. Motors that are located aboveground use the air around them for cooling, sometimes with the assistance of a fan. In the case of a submersible motor, the water being pumped is used to cool the motor and provide a long, reliable service life.

There are two keys to keeping a submersible motor cool: making sure there is water flowing past the motor, and that there is enough of it. Even though the motor is submerged in water, several situations are possible in which water could enter above the motor. In these cases, water will enter at the pump intake and never pass the motor. Examples of this type of situation would be an
open body of water, a pump sitting below the casing/perforations or a top-feeding (cascading) rock well. In these situations, the motor requires a fl ow sleeve. Page 6 of the Franklin Application, Installation, Maintenance (AIM) manual explains how a flow inducer sleeve is constructed. One important note: for the flow sleeve to be effective, it must extend past the bottom of the motor. Once water flow past the motor has been confirmed, the amount of flow must also be checked. Continue reading

# Why can’t I hear the radio? VFDs and Interference Issues

When properly installed, variable frequency drives (VFDs) offer many advantages over conventional systems, including constant pressure, soft starting, and the option of a small, space-saving tank. While these advantages far outweigh the chance of ever experience a problem, in certain circumstances, all VFDs have the potential to create electromagnetic interference (EMI). Observing proper installation and grounding procedures greatly reduces the chances of EMI, and this issue of Franklin AID discusses a few simple steps to do just that. Continue reading

# Pump Curves, VFDs and Pressure Reducing Valves

Understanding pump curves is critical to any submersible applications, whether it is controlled by a standard pressure switch, a variable frequency drive (VFD), or a pressure-reducing valve (PRV). In addition to helping you product the right amount of water, avoid conditions that may be harmful to the pump (e.g. upthroust), and maximize efficiency, understand pump curves can help you actually visualize and understand the differences between standard systems and VFD systems, and PRV systems. This issue of Franklin AID will walk you through the steps you need to do that. Continue reading

If there is such a thing as an unsung hero in an electrical motor, it has to be the overload. Overloads play a crucial role in protecting submersible electric motors from overheat conditions. For this reason, Franklin Electric supplies overloads for all of its single-phase submersible motors. Depending on the motor design and horsepower, the overloads may be located externally in a control box or internally in the motor itself. Since we recently made some changes to the overload placement in our 1.5 horsepower (hp) motors and controls, we thought now would be a good time to review how overloads work and what they are designed to protect. We’ll also review your options as a professional water systems contractor when it comes to overloads in our 1.5 hp product. Continue reading

# Certified Contractor Program

The water systems professionals who install Franklin Electric products are in a class by themselves, and Franklin Electric takes a great deal of pride in our commitment to their technical training. For example, in 2007, we presented 677 hours of technical training to 5,500 water systems contractors and distributor personnel. In 2007, we also opened dedicated training centers in Wilburton, Oklahoma and Bolton, Ontario. Then, this January we cut the ribbon on our Electronics Training Center in Grant County, Indiana. No one else in our industry can compare.

# New Tools for Your Business

As a water systems professional, you wear a lot of different hats: groundwater expert, overall technical expert, businessperson, and salesperson … the list goes on. With all the different roles you fill, you need more than wrenches and drill rigs and voltmeters in your proverbial tool bag to get the job done. This issue of Franklin AID introduces a few new “tools” from Franklin Electric. Each is designed specifically to support you and your business. Continue reading

# What makes a submersible motor different?

As a professional water systems contractor, you’ve probably faced situations like this: you’re installing a submersible pump/motor, and the homeowner wants to know why a submersible unit costs “so much”. He may have formed this opinion because he recently replaced a motor in an HVAC unit, a sump pump, or even a jet pump. In any case, chances are good that he is comparing the submersible to an aboveground motor or pump. As you know, this is a classic case of comparing apples to oranges, since submersible motors are very different from aboveground motors. This issue of Franklin AID will review some key aspects of submersible motor construction in order to help professional water systems contractors like you explain to a homeowner why a submersible motor appears to be more expensive, but worth the cost. Continue reading