1 Fan Application . FA/113-01. product Application guide A technical bulletin for engineers, contractors and students in the air movement and control industry. Motor Application guide for Ventilation Products The evaluation of a fan's motor is a time consuming refer to the Table of Contents to locate the part of the design of air handling equipment. appropriate category. Selection of the proper electrical characteristics and construction features can involve factors not known Motor applications to everyone. The purpose of this article is to aid in When selecting the proper motor for the the selection of the correct motor type from an Application , there are many overlooked electrical and mechanical standpoint for a given considerations.
2 The two most common are: Application and fan type. Physical size: Space available for Table of Contents Page Understanding the material in this article will help you identify and eliminate Application problems motor mounting Motor applications ..1. before they are encountered. When selecting a Motor & fan size may limit selections. motor, make sure the fan and Application are in Many two speed limitations sync with each other. For example, money is wasted and explosion Belt drive vs. direct drive when putting an expensive, special duty motor resistant motors Motor enclosures ..2. costing hundreds (or sometimes thousands) of may not fit in a fan Open dollars extra on a fan used in normal clean air that was not Totally enclosed applications .
3 The overall benefit is not having to originally designed Explosion resistant deal with special design requests that result in for such applica- Motor types ..4. unnecessary extra expense and longer lead times. tions, especially Single-phase those selected for Three-phase Most often the fan manufacturer will recommend low cfm. the proper standard motor for the Application . If Summary chart your Application requires special consideration, an Belt drive fans vs. Motor speed ..6. outline of the factors to consider in evaluating fan direct drive fans: Multi-speed motors motor performance is included for reference. Please Selection of belt Voltage and phase driven versus Service factor direct driven fans Efficiency.
4 8. should involve Epact consideration of Insulation .. fan sound levels, Mounting ..10. motor cost, and maintenance. The Motor protection (Thermal belt driven fan has overload) ..10. pulleys, shafts, Underwriters Laboratory bearings, and (UL) ..10. belt(s) which Testing at Greenheck ..11. contribute to cost. Glossary of terms ..12. However, lower . Box 410 Schofield, WI 54476 Fax Copyright 2001 Greenheck Fan Corp. Greenheck product Application guide cost, higher speed motors are generally used. Belt protection from airborne dust or chemical vapor. driven fans are typically less efficient due to belt Typically used on small centrifugal roof fans with the and bearing losses.
5 Selection of larger, slower motor out of airstream where the air is clean and dry. moving belt driven fans will generate less noise for Totally enclosed: Prevents free exchange of air a given Application . Smaller direct drive fans will between the inside and outside of the case, but not have a faster rotating wheel for the same air sufficiently enclosed to be termed airtight. Totally delivery and be more efficient, however generate enclosed motors are best suited for use in humid more noise. Belt driven fans and very large or heavy environments or dusty, contaminated atmospheres. direct driven fans require high starting torque of Some totally enclosed motors are also available for split-phase, capacitor-start, or three-phase motors.
6 The more severe applications . Direct driven motors work great where access to bearings and belts are difficult. Motors for belt Totally enclosed fan cooled (TEFC): A totally driven fans are typically 1725 rpm (60 cycle), while enclosed fan cooled motor that is equipped for direct drive fans have specific motor rpm's available exterior cooling by means of a fan integral to the to accommodate for no pulley adjustment. Typically, motor but external to the enclosed parts. when motors are lower than 1725 rpm, they cost more, are physically larger, have longer leadtimes, Application : Used and have fewer motor options available.
7 When protection from dust, moisture, Motor enclosures rain and non- Many types of motor enclosures are available for all explosive conditions from open to explosion resistant. The atmospheres are most common motor enclosures used with fans are required and open and totally enclosed. There are several inadequate airflow different types within each enclosure. In most cases, over the motor is it is best to let the fan manufacturer select within the provided by the Totally Enclosed Fan Cooled Motor subcategory of enclosures. device it drives. These motors are typically used on belt driven inline or duct fans. Open: Has ventilation openings which permit passage of external cooling air over and around the Totally enclosed air over (TEAO): A totally windings of the motor.
8 The term open designates enclosed air over motor is not self ventilated and having no restriction to ventilation other than that must be cooled by means external to the motor. necessitated by mechanical construction. An open Application : These motors are used when protection is dripproof (ODP) motor is where ventilating required from dust, moisture, rain, and non-explosive openings are constructed such that operation is not atmospheres. These motors are not self-cooling, so they interfered with when drops of liquid or solid are typically used where the driven device is a fan or particles strike or enter the enclosure at any angle blower that provides the necessary air movement over the from 0 to 15 degrees downward from vertical.
9 The motor for cooling. It is important that the airflow over the motor must be mounted in the proper orientation motor is of high enough velocity to equal or exceed the for the open dripproof enclosure to function as cooling offered by an integral fan. These motors are designed. typically used on sidewall propeller fans, direct drive Application : axial fans, and vane axial fans. Suitable for Totally enclosed special duty: Severe duty motors indoor use and are always totally enclosed, three-phase, cast iron in relatively casing with Class F insulation. They are designed clean for use in extremely moist or chemical environments atmospheres but not for hazardous locations.
10 These are typically that are fairly called marine duty or chemical duty. dry and well ventilated. They A washdown duty motor is totally enclosed and Open drip-proof motor built to handle high-pressure washdowns. These do not offer 2 . Fan Application No. FA/113-01. Greenheck product Application guide motors are used in wet environments and where within closed containers or systems from which motors are subject to repeated washdowns. they can escape only in the event of an accidental breakdown or abnormal operations. Explosion resistant (EXP): A totally enclosed motor is designed and constructed to withstand an internal Class II locations: These are hazardous because of explosion of specified gases or vapors, and not the presence of combustible dust.