DELOACH BLOG

In an industrial environment, electric motors are used for a variety of applications.

These often include pumping water or other fluids, transporting material on conveyors or lifts, or providing motive force to moving parts of a mechanical device. The electric motor dominates the field whenever something needs to move. Regardless of the end user, all these motors will have one thing in common, a motor controller.

A motor controller is a device with the means to turn the motor on and off, provide circuit protection, and serve as a disconnecting means to render the circuit safe during maintenance. Traditionally, this is done with a direct-on-line (DOL) motor starter. A DOL starter installation consists of a branch breaker combined with a DOL motor starter and overload module. In a typical DOL motor starter installation, the branch breaker will serve as short circuit protection, as well as a means of electrical disconnect. The motor starter unit is essentially a large relay with a magnetic coil and high-power contacts held apart by springs. When the motor is called to run, the magnetic coil is energized, pulling in the contacts and bridging the line side to the load side terminals, allowing power to flow. Once the motor starter has contact, electrical power flows out through an overload disconnect module, and then to the electric motor. The DOL motor starter is a well-proven design that is familiar to almost anyone in the industrial space and is still what is found in a majority of applications.

Different types of electric pumps, blowers, compressors,

and even material conveying equipment utilized to operate a water treatment process facility whether it is municipal, industrial, aquaculture, or a pisciculture facility.  All of these applications share a common requirement which is the need to have an electric motor provide the torque and energy necessary to operate the equipment and perform the required function. 

One of the most common questions asked or considered during the design phase of the water treatment process is what type of motor enclosure should be selected.  There are 7 

types of motor enclosures that are available and defined by NEMA standards MG1-1.25 through MG 1.27.  The final decision should be driven by the all of demands that the application will have placed upon it.

The selection of the type of motor enclosure can be a difficult choice. 

If the application is for a process like Reverse Osmosis, Degasification, or Decarbonation, it is important to consider the efficiency of the motor and what the motor will be exposed to during its operating life cycle.    We will briefly review each of the 7 different types that NEMA defines for motor enclosure types. 

The ODP (open drip proof) is one of the most common types of enclosures. 

The enclosure is open and vented at the back end of the motor and allows air to circulate in and around the motor windings carrying off heat.  The ODP motor is designed to prevent liquid from entering the motor at a 15-degree angle based on the vertical alignment.  ODP motors are normally utilized at water treatment facilities or aquaculture facilities where they will not be exposed to corrosive conditions such as HVAC systems.